Array ( [0] => {{short description|Biological technique to control the activity of neurons or other cell types with light}} [1] => {{about|controlling cellular activity with light|genetically encoded sensors|Optogenetic methods to record cellular activity}} [2] => '''Optogenetics''' is a biological technique to control the activity of [[neurons]] or other cell types with light. This is achieved by [[Gene expression|expression]] of [[Channelrhodopsin|light-sensitive ion channels]], [[Halorhodopsin|pumps]] or [[Photoactivated adenylyl cyclase|enzymes]] specifically in the target cells. On the level of individual [[Cell (biology)|cells]], [[Photoactivated adenylyl cyclase|light-activated enzymes]] and [[transcription factor]]s allow precise control of biochemical signaling pathways.{{cite journal | vauthors = Shimizu-Sato S, Huq E, Tepperman JM, Quail PH | title = A light-switchable gene promoter system | journal = Nature Biotechnology | volume = 20 | issue = 10 | pages = 1041–1044 | date = October 2002 | pmid = 12219076 | doi = 10.1038/nbt734 | s2cid = 24914960 }} In [[Neuroscience|systems neuroscience]], the ability to control the activity of a genetically defined set of neurons has been used to understand their contribution to decision making,{{cite journal | vauthors = Guo ZV, Li N, Huber D, Ophir E, Gutnisky D, Ting JT, Feng G, Svoboda K | display-authors = 6 | title = Flow of cortical activity underlying a tactile decision in mice | journal = Neuron | volume = 81 | issue = 1 | pages = 179–194 | date = January 2014 | pmid = 24361077 | pmc = 3984938 | doi = 10.1016/j.neuron.2013.10.020 }} learning,{{cite journal | vauthors = Lak A, Okun M, Moss MM, Gurnani H, Farrell K, Wells MJ, Reddy CB, Kepecs A, Harris KD, Carandini M | display-authors = 6 | title = Dopaminergic and Prefrontal Basis of Learning from Sensory Confidence and Reward Value | journal = Neuron | volume = 105 | issue = 4 | pages = 700–711.e6 | date = February 2020 | pmid = 31859030 | pmc = 7031700 | doi = 10.1016/j.neuron.2019.11.018 }} fear memory,{{cite journal | vauthors = Liu X, Ramirez S, Pang PT, Puryear CB, Govindarajan A, Deisseroth K, Tonegawa S | title = Optogenetic stimulation of a hippocampal engram activates fear memory recall | journal = Nature | volume = 484 | issue = 7394 | pages = 381–385 | date = March 2012 | pmid = 22441246 | pmc = 3331914 | doi = 10.1038/nature11028 | bibcode = 2012Natur.484..381L }} mating,{{cite journal | vauthors = Tanaka R, Higuchi T, Kohatsu S, Sato K, Yamamoto D | title = Optogenetic Activation of the ''fruitless''-Labeled Circuitry in ''Drosophila subobscura'' Males Induces Mating Motor Acts | journal = The Journal of Neuroscience | volume = 37 | issue = 48 | pages = 11662–11674 | date = November 2017 | pmid = 29109241 | pmc = 6705751 | doi = 10.1523/JNEUROSCI.1943-17.2017 }} addiction,{{cite journal | vauthors = Stamatakis AM, Stuber GD | title = Optogenetic strategies to dissect the neural circuits that underlie reward and addiction | journal = Cold Spring Harbor Perspectives in Medicine | volume = 2 | issue = 11 | pages = a011924 | date = November 2012 | pmid = 23043156 | pmc = 3543095 | doi = 10.1101/cshperspect.a011924 }} feeding,{{Cite journal|last1= Musso|first1= Pierre-Yves |last2= Junca|first2= Pierre|last3= Jelen|first3= Meghan|last4= Feldman-Kiss|first4= Damian|last5= Zhang|first5= Han |last6= Chan|first6= Rachel CW|last7= Gordon|first7= Michael D|date= 2019-07-19|editor-last= Ramaswami|editor-first= Mani|editor2-last=Dulac|editor2-first=Catherine|title=Closed-loop optogenetic activation of peripheral or central neurons modulates feeding in freely moving Drosophila|journal= eLife|volume= 8|pages= e45636|doi= 10.7554/eLife.45636|pmid=31322499|pmc=6668987|issn=2050-084X |doi-access=free }} and locomotion.{{Cite journal|last1= Feng|first1= Kai|last2= Sen|first2= Rajyashree|last3= Minegishi|first3= Ryo|last4= Dübbert|first4= Michael|last5= Bockemühl|first5= Till|last6= Büschges|first6= Ansgar|last7= Dickson|first7= Barry J.|date= 2020-12-02 |title= Distributed control of motor circuits for backward walking in Drosophila|journal=Nature Communications |language= en|volume= 11|issue= 1|pages= 6166|doi= 10.1038/s41467-020-19936-x|pmid= 33268800|pmc= 7710706 |bibcode= 2020NatCo..11.6166F|s2cid= 227255627|issn= 2041-1723}} In a first medical application of optogenetic technology, vision was partially restored in a blind patient with [[Retinitis pigmentosa]]. [3] => [4] => Optogenetic techniques have also been introduced to map the [[Brain connectivity estimators|functional connectivity]] of the brain''.''{{Cite journal|last1= Lim|first1= Diana|last2= LeDue|first2= Jeffrey|last3= Mohajerani|first3= Majid|last4= Vanni|first4= Matthieu|last5= Murphy|first5= Timothy|date= 2013|title= Optogenetic approaches for functional mouse brain mapping|journal=Frontiers in Neuroscience|volume= 7|page= 54|doi= 10.3389/fnins.2013.00054 |pmid= 23596383|pmc=3622058|issn=1662-453X|doi-access=free}}{{Cite journal|last1= Lee|first1= Candice |last2= Lavoie|first2= Andreanne|last3= Liu|first3= Jiashu|last4= Chen|first4= Simon X.|last5= Liu|first5= Bao-hua |date= 2020 |title= Light Up the Brain: The Application of Optogenetics in Cell-Type Specific Dissection of Mouse Brain Circuits|journal=Frontiers in Neural Circuits|volume= 14|page= 18|doi= 10.3389/fncir.2020.00018|pmid= 32390806 |pmc= 7193678|issn= 1662-5110|doi-access= free}} By altering the activity of genetically labelled neurons with light and by using imaging and electrophysiology techniques to record the activity of other cells, researchers can identify the [[Independence (probability theory)|statistical dependencies]] between cells and brain regions.{{Cite journal|last1= Franconville|first1= Romain|last2= Beron|first2= Celia|last3= Jayaraman|first3= Vivek|date= 2018-08-20|editor-last= VijayRaghavan|editor-first= K|editor2-last= Scott|editor2-first= Kristin|editor3-last= Heinze |editor3-first= Stanley|title=Building a functional connectome of the Drosophila central complex|journal= eLife |volume= 7|pages= e37017|doi= 10.7554/eLife.37017|pmid= 30124430|pmc= 6150698|issn= 2050-084X |doi-access= free }}{{Cite journal|last1= Chen|first1= Chenghao|last2= Agrawal|first2= Sweta|last3= Mark|first3= Brandon|last4= Mamiya|first4= Akira|last5= Sustar|first5= Anne|last6= Phelps|first6= Jasper S.|last7= Lee|first7= Wei-Chung Allen |last8= Dickson|first8= Barry J.|last9= Card|first9= Gwyneth M.|last10= Tuthill|first10= John C.|date= 2021-12-06 |title= Functional architecture of neural circuits for leg proprioception in Drosophila|journal=Current Biology |language= en|volume= 31|issue=23|pages=5163–5175.e7|doi= 10.1016/j.cub.2021.09.035|pmid= 34637749|pmc= 8665017|issn= 0960-9822}} [5] => [6] => In a broader sense, the field of optogenetics also includes methods to [[Optogenetic methods to record cellular activity|record cellular activity]] with [[genetically encoded indicator]]s. [7] => [8] => In 2010, optogenetics was chosen as the "Method of the Year" across all fields of science and engineering by the interdisciplinary research journal ''[[Nature Methods]]''.Primer on Optogenetics: {{cite journal|doi=10.1038/nmeth.f.323|title=Optogenetics: Controlling cell function with light|year=2010| vauthors = Pastrana E |journal=Nature Methods|volume=8|pages=24–25|issue=1|s2cid=5808517}}
Editorial: {{cite journal|doi=10.1038/nmeth.f.321|title=Method of the Year 2010|year=2010|journal=Nature Methods|volume=8|pages=1|issue=1|doi-access=free}}
Commentary: {{cite journal | vauthors = Deisseroth K | title = Optogenetics | journal = Nature Methods | volume = 8 | issue = 1 | pages = 26–29 | date = January 2011 | pmid = 21191368 | pmc = 6814250 | doi = 10.1038/nmeth.f.324 }} In the same year an article on "Breakthroughs of the Decade" in the academic research journal [[Science (journal)|''Science'']] highlighted optogenetics.{{cite journal | title = Insights of the decade. Stepping away from the trees for a look at the forest. Introduction | journal = Science | volume = 330 | issue = 6011 | pages = 1612–1613 | date = December 2010 | pmid = 21163985 | doi = 10.1126/science.330.6011.1612 | s2cid = 206593135 | bibcode = 2010Sci...330.1612. | author1 = News Staff }} [9] => {{cite web | url = https://www.youtube.com/watch?v=I64X7vHSHOE | title = Method of the Year 2010: Optogenetics | work = Nature Video | date = 17 December 2010 }}{{cite web| vauthors = Deisseroth K |date=20 October 2010|title= Optogenetics: Controlling the Brain with Light |url= http://www.scientificamerican.com/article.cfm?id=optogenetics-controlling |work= Scientific American |publisher= Springer Nature America, Inc.}} [10] => [11] => ==History== [12] => In 1979, [[Francis Crick]] suggested that controlling all cells of one type in the brain, while leaving the others more or less unaltered, is a real challenge for neuroscience. Crick speculated that a technology using light might be useful to control neuronal activity with temporal and spatial precision but at the time there was no technique to make neurons responsive to light. [13] => [14] => By the early 1990s LC Katz and E Callaway had shown that light could uncage glutamate.{{cite journal | vauthors = Crick F | title = The impact of molecular biology on neuroscience | journal = Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences | volume = 354 | issue = 1392 | pages = 2021–2025 | date = December 1999 | pmid = 10670022 | pmc = 1692710 | doi = 10.1098/rstb.1999.0541 }} Heberle and Büldt in 1994 had already shown functional heterologous expression of a bacteriorhodopsin for light-activated ion flow in yeast.{{cite journal | vauthors = Hoffmann A, Hildebrandt V, Heberle J, Büldt G | title = Photoactive mitochondria: in vivo transfer of a light-driven proton pump into the inner mitochondrial membrane of Schizosaccharomyces pombe | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 91 | issue = 20 | pages = 9367–9371 | date = September 1994 | pmid = 7937771 | pmc = 44813 | doi = 10.1073/pnas.91.20.9367 | doi-access = free | bibcode = 1994PNAS...91.9367H }} [15] => [16] => In 1995, [[Georg Nagel]] et al. and [[Ernst Bamberg]] tried the heterologous expression of microbial [[rhodopsin]]s (also bacteriorhodopsin and also in a non-neural system, Xenopus oocytes) (Georg Nagel et al., 1995, FEBS Lett.) and showed light-induced current. [17] => [18] => The earliest genetically targeted method that used light to control rhodopsin-sensitized neurons was reported in January 2002, by [[Boris Valery Zemelman|Boris Zemelman]] and [[Gero Miesenböck]], who employed ''[[Drosophila]]'' rhodopsin cultured mammalian neurons.{{cite journal | vauthors = Zemelman BV, Lee GA, Ng M, Miesenböck G | title = Selective photostimulation of genetically chARGed neurons | journal = Neuron | volume = 33 | issue = 1 | pages = 15–22 | date = January 2002 | pmid = 11779476 | doi = 10.1016/S0896-6273(01)00574-8 | s2cid = 16391269 | doi-access = free }} In 2003, Zemelman and Miesenböck developed a second method for light-dependent activation of neurons in which single ionotropic channels TRPV1, TRPM8 and P2X2 were gated by photocaged ligands in response to light.{{cite journal | vauthors = Zemelman BV, Nesnas N, Lee GA, Miesenbock G | title = Photochemical gating of heterologous ion channels: remote control over genetically designated populations of neurons | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 100 | issue = 3 | pages = 1352–1357 | date = February 2003 | pmid = 12540832 | pmc = 298776 | doi = 10.1073/pnas.242738899 | doi-access = free | bibcode = 2003PNAS..100.1352Z }} Beginning in 2004, the Kramer and Isacoff groups developed organic photoswitches or "reversibly caged" compounds in collaboration with the [[Dirk Trauner|Trauner]] group that could interact with genetically introduced ion channels.{{cite journal | vauthors = Banghart M, Borges K, Isacoff E, Trauner D, Kramer RH | title = Light-activated ion channels for remote control of neuronal firing | journal = Nature Neuroscience | volume = 7 | issue = 12 | pages = 1381–1386 | date = December 2004 | pmid = 15558062 | pmc = 1447674 | doi = 10.1038/nn1356 }}{{cite journal | vauthors = Volgraf M, Gorostiza P, Numano R, Kramer RH, Isacoff EY, Trauner D | title = Allosteric control of an ionotropic glutamate receptor with an optical switch | journal = Nature Chemical Biology | volume = 2 | issue = 1 | pages = 47–52 | date = January 2006 | pmid = 16408092 | pmc = 1447676 | doi = 10.1038/nchembio756 }} TRPV1 methodology, albeit without the illumination trigger, was subsequently used by several laboratories to alter feeding, locomotion and behavioral resilience in laboratory animals.{{cite journal | vauthors = Arenkiel BR, Klein ME, Davison IG, Katz LC, Ehlers MD | title = Genetic control of neuronal activity in mice conditionally expressing TRPV1 | journal = Nature Methods | volume = 5 | issue = 4 | pages = 299–302 | date = April 2008 | pmid = 18327266 | pmc = 3127246 | doi = 10.1038/nmeth.1190 }}{{cite journal | vauthors = Güler AD, Rainwater A, Parker JG, Jones GL, Argilli E, Arenkiel BR, Ehlers MD, Bonci A, Zweifel LS, Palmiter RD | display-authors = 6 | title = Transient activation of specific neurons in mice by selective expression of the capsaicin receptor | journal = Nature Communications | volume = 3 | pages = 746 | date = March 2012 | pmid = 22434189 | pmc = 3592340 | doi = 10.1038/ncomms1749 | bibcode = 2012NatCo...3..746G }}{{cite journal | vauthors = Wang M, Perova Z, Arenkiel BR, Li B | title = Synaptic modifications in the medial prefrontal cortex in susceptibility and resilience to stress | journal = The Journal of Neuroscience | volume = 34 | issue = 22 | pages = 7485–7492 | date = May 2014 | pmid = 24872553 | pmc = 4035514 | doi = 10.1523/JNEUROSCI.5294-13.2014 }} However, light-based approaches for altering neuronal activity were not applied outside the original laboratories, likely because the easier to employ channelrhodopsin was cloned soon thereafter.{{cite journal | vauthors = Nagel G, Szellas T, Huhn W, Kateriya S, Adeishvili N, Berthold P, Ollig D, Hegemann P, Bamberg E | display-authors = 6 | title = Channelrhodopsin-2, a directly light-gated cation-selective membrane channel | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 100 | issue = 24 | pages = 13940–13945 | date = November 2003 | pmid = 14615590 | pmc = 283525 | doi = 10.1073/pnas.1936192100 | doi-access = free | bibcode = 2003PNAS..10013940N }} [19] => [20] => [[Peter Hegemann]], studying the [[Phototaxis|light response]] of green algae at the University of Regensburg, had discovered photocurrents that were too fast to be explained by the classic g-protein-coupled [[Rhodopsin|animal rhodopsins]].{{cite journal | vauthors = Harz H, Hegemann P |date=1991-06-06 |title=Rhodopsin-regulated calcium currents in Chlamydomonas |journal=Nature |volume=351 |issue=6326 |pages=489–491 |doi=10.1038/351489a0 |bibcode=1991Natur.351..489H |s2cid=4309593 }} Teaming up with the electrophysiologist Georg Nagel at the Max Planck Institute in Frankfurt, they could demonstrate that a single gene from the alga ''[[Chlamydomonas reinhardtii|Chlamydomonas]]'' produced large photocurrents when expressed in the oocyte of a frog.{{cite journal | vauthors = Nagel G, Ollig D, Fuhrmann M, Kateriya S, Musti AM, Bamberg E, Hegemann P | title = Channelrhodopsin-1: a light-gated proton channel in green algae | journal = Science | volume = 296 | issue = 5577 | pages = 2395–2398 | date = June 2002 | pmid = 12089443 | doi = 10.1126/science.1072068 | s2cid = 206506942 | bibcode = 2002Sci...296.2395N }} To identify expressing cells, they replaced the cytoplasmic tail of the algal protein with a fluorescent protein [[YFP]], generating the first generally applicable optogenetic tool. They stated in the 2003 paper that "expression of ChR2 in oocytes or mammalian cells may be used as a powerful tool to increase cytoplasmic Ca2+ concentration or to depolarize the cell membrane, simply by illumination". [21] => [22] => [[Karl Deisseroth]] in the Bioengineering Department at Stanford published the notebook pages from early July 2004 of his initial experiment showing light activation of neurons expressing a channelrhodopsin.{{cite journal | vauthors = Deisseroth K | title = Optogenetics: 10 years of microbial opsins in neuroscience | journal = Nature Neuroscience | volume = 18 | issue = 9 | pages = 1213–1225 | date = September 2015 | pmid = 26308982 | pmc = 4790845 | doi = 10.1038/nn.4091 }} In August 2005, his laboratory staff, including graduate students [[Edward Boyden|Ed Boyden]] and [[Feng Zhang]], in collaboration with Georg Nagel, published the first demonstration of a single-component optogenetic system, in neurons{{cite journal | vauthors = Boyden ES, Zhang F, Bamberg E, Nagel G, Deisseroth K | title = Millisecond-timescale, genetically targeted optical control of neural activity | journal = Nature Neuroscience | volume = 8 | issue = 9 | pages = 1263–1268 | date = September 2005 | pmid = 16116447 | doi = 10.1038/nn1525 | s2cid = 6809511 }} using the channelrhodopsin-2(H134R)-eYFP mutant from Georg Nagel, which is the first mutant of channelrhodopsin-2 since its functional characterization by Georg Nagel and Hegemann. [23] => [24] => [[Zhuo-Hua Pan]] of [[Wayne State University]], researching on restore sight to blindness, tried channelrhodopsin out in ganglion cells—the neurons in human eyes that connect directly to the brain. Pan's first observation of optical activation of retinal neurons with channelrhodopsin was in February 2004 according to Pan,{{cite web|url=https://www.statnews.com/2016/09/01/optogenetics/|date=1 September 2016|website=STAT|language=en-US|access-date=9 February 2020|title=He may be the rightful inventor of neuroscience's biggest breakthrough in decades. But you've never heard of him}} five months before Deisseroth's initial observation in July 2004.{{cite journal |last1=Deisseroth |first1=Karl |title=Optogenetics: 10 years of microbial opsins in neuroscience |journal=Nature Neuroscience |date=26 August 2015 |volume=18 |issue=9 |pages=1213–1225 |doi=10.1038/nn.4091 |pmid=26308982 |pmc=4790845 }} Indeed, the transfected neurons became electrically active in response to light, and in 2005 Zhuo-Hua Pan reported successful in-vivo transfection of channelrhodopsin in retinal ganglion cells of mice, and electrical responses to photostimulation in retinal slice culture.{{cite journal | vauthors = Bi A, Cui J, Ma YP, Olshevskaya E, Pu M, Dizhoor AM, Pan ZH | title = Ectopic expression of a microbial-type rhodopsin restores visual responses in mice with photoreceptor degeneration | journal = Neuron | volume = 50 | issue = 1 | pages = 23–33 | date = April 2006 | pmid = 16600853 | pmc = 1459045 | doi = 10.1016/j.neuron.2006.02.026 }} This approach was eventually realized in a human patient by [[Botond Roska]] and coworkers in 2021. [25] => [26] => In April 2005, [[Susana Lima]] and Miesenböck reported the first use of genetically targeted P2X2 [[photostimulation]] to control the behaviour of an animal.{{cite journal | vauthors = Lima SQ, Miesenböck G | title = Remote control of behavior through genetically targeted photostimulation of neurons | journal = Cell | volume = 121 | issue = 1 | pages = 141–152 | date = April 2005 | pmid = 15820685 | doi = 10.1016/j.cell.2005.02.004 | s2cid = 14608546 | doi-access = free }} They showed that photostimulation of genetically circumscribed groups of neurons, such as those of the [[dopaminergic]] system, elicited characteristic behavioural changes in fruit flies. [27] => [28] => In October 2005, Lynn Landmesser and Stefan Herlitze also published the use of channelrohodpsin-2 to control neuronal activity in cultured hippocampal neurons and chicken spinal cord circuits in intact developing embryos.{{cite journal | vauthors = Li X, Gutierrez DV, Hanson MG, Han J, Mark MD, Chiel H, Hegemann P, Landmesser LT, Herlitze S | display-authors = 6 | title = Fast noninvasive activation and inhibition of neural and network activity by vertebrate rhodopsin and green algae channelrhodopsin | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 102 | issue = 49 | pages = 17816–17821 | date = December 2005 | pmid = 16306259 | pmc = 1292990 | doi = 10.1073/pnas.0509030102 | doi-access = free | bibcode = 2005PNAS..10217816L }} In addition, they introduced for the first time vertebrate rhodopsin, a light-activated G protein coupled receptor, as a tool to inhibit neuronal activity via the recruitment of intracellular signaling pathways also in hippocampal neurons and the intact developing chicken embryo. [29] => [30] => The groups of [[Alexander Gottschalk]] and Georg Nagel made the first ChR2 mutant (H134R) and were first to use channelrhodopsin-2 for controlling neuronal activity in an intact animal, showing that motor patterns in the roundworm ''[[Caenorhabditis elegans|C. elegans]]'' could be evoked by light stimulation of genetically selected neural circuits (published in December 2005).{{cite journal | vauthors = Nagel G, Brauner M, Liewald JF, Adeishvili N, Bamberg E, Gottschalk A | title = Light activation of channelrhodopsin-2 in excitable cells of Caenorhabditis elegans triggers rapid behavioral responses | journal = Current Biology | volume = 15 | issue = 24 | pages = 2279–2284 | date = December 2005 | pmid = 16360690 | doi = 10.1016/j.cub.2005.11.032 | s2cid = 7036529 | doi-access = free }} In mice, controlled expression of optogenetic tools is often achieved with cell-type-specific Cre/loxP methods developed for neuroscience by [[Joe Z. Tsien]] back in the 1990s{{cite journal | vauthors = Tsien JZ, Chen DF, Gerber D, Tom C, Mercer EH, Anderson DJ, Mayford M, Kandel ER, Tonegawa S | display-authors = 6 | title = Subregion- and cell type-restricted gene knockout in mouse brain | journal = Cell | volume = 87 | issue = 7 | pages = 1317–1326 | date = December 1996 | pmid = 8980237 | doi = 10.1016/S0092-8674(00)81826-7 | s2cid = 863399 | doi-access = free }} to activate or inhibit specific brain regions and cell-types ''in vivo''.{{cite journal | vauthors = Tsien JZ | title = Cre-Lox Neurogenetics: 20 Years of Versatile Applications in Brain Research and Counting… | journal = Frontiers in Genetics | volume = 7 | pages = 19 | year = 2016 | pmid = 26925095 | pmc = 4759636 | doi = 10.3389/fgene.2016.00019 | doi-access = free }} [31] => [32] => In 2007, the labs of Boyden and Deisseroth (together with the groups of Gottschalk and Georg Nagel) simultaneously reported successful optogenetic inhibition of activity in neurons.{{cite journal | vauthors = Han X, Boyden ES | title = Multiple-color optical activation, silencing, and desynchronization of neural activity, with single-spike temporal resolution | journal = PLOS ONE | volume = 2 | issue = 3 | pages = e299 | date = March 2007 | pmid = 17375185 | pmc = 1808431 | doi = 10.1371/journal.pone.0000299 | publisher = Public Library of Science | name-list-style = vanc | doi-access = free | bibcode = 2007PLoSO...2..299H | oclc = 678618519 }}{{cite journal | vauthors = Zhang F, Wang LP, Brauner M, Liewald JF, Kay K, Watzke N, Wood PG, Bamberg E, Nagel G, Gottschalk A, Deisseroth K | display-authors = 6 | title = Multimodal fast optical interrogation of neural circuitry | journal = Nature | volume = 446 | issue = 7136 | pages = 633–639 | date = April 2007 | pmid = 17410168 | doi = 10.1038/nature05744 | s2cid = 4415339 | bibcode = 2007Natur.446..633Z }} [33] => [34] => In 2007, Georg Nagel and Hegemann's groups started the optogenetic manipulation of cAMP.{{cite journal | vauthors = Schröder-Lang S, Schwärzel M, Seifert R, Strünker T, Kateriya S, Looser J, Watanabe M, Kaupp UB, Hegemann P, Nagel G | display-authors = 6 | title = Fast manipulation of cellular cAMP level by light in vivo | journal = Nature Methods | volume = 4 | issue = 1 | pages = 39–42 | date = January 2007 | pmid = 17128267 | doi = 10.1038/nmeth975 | s2cid = 10616442 | url = http://edoc.hu-berlin.de/18452/10021 }} In 2014, Avelar et al. reported the first rhodopsin-guanylyl cyclase gene from fungus. In 2015, Scheib et al. and Gao et al. characterized the activity of the rhodopsin-guanylyl cyclase gene. And Shiqiang Gao et al. and Georg Nagel, Alexander Gottschalk identified it as the first 8 TM rhodopsin.{{cite journal | vauthors = Gao S, Nagpal J, Schneider MW, Kozjak-Pavlovic V, Nagel G, Gottschalk A | title = Optogenetic manipulation of cGMP in cells and animals by the tightly light-regulated guanylyl-cyclase opsin CyclOp | journal = Nature Communications | volume = 6 | issue = 1 | pages = 8046 | date = September 2015 | pmid = 26345128 | pmc = 4569695 | doi = 10.1038/ncomms9046 | doi-access = free | bibcode = 2015NatCo...6.8046G }} [35] => [36] => ==Description== [37] => [[File:Example of optogenetic activation of prefrontal cortex.jpg|thumb|upright=1.6|right|'''Fig 1.''' Channelrhodopsin-2 (ChR2) induces temporally precise blue light-driven activity in rat prelimbic prefrontal cortical neurons. a) ''In vitro'' schematic (left) showing blue light delivery and whole-cell patch-clamp recording of light-evoked activity from a fluorescent CaMKllα::ChR2-EYFP expressing pyramidal neuron (right) in an acute brain slice. b) ''In vivo'' schematic (left) showing blue light (473 nm) delivery and single-unit recording. (bottom left) Coronal brain slice showing expression of CaMKllα::ChR2-EYFP in the prelimbic region. Light blue arrow shows tip of the optical fiber; black arrow shows tip of the recording electrode (left). White bar, 100 [[µm]]. (bottom right) ''In vivo'' light recording of prefrontal cortical neuron in a transduced CaMKllα::ChR2-EYFP rat showing light-evoked spiking to 20 Hz delivery of blue light pulses (right). Inset, representative light-evoked single-unit response.]] [38] => [[File:Cooper laboratory recording of optogenetic silencing of prefrontal cortical neuron.jpg|upright=1.6|thumb|right|'''Fig 2'''. Halorhodopsin (NpHR) rapidly and reversibly silences spontaneous activity ''in vivo'' in rat prelimbic prefrontal cortex. (Top left) Schematic showing ''in vivo'' green (532 nm) light delivery and single- unit recording of a spontaneously active CaMKllα::eNpHR3.0- EYFP expressing pyramidal neuron. (Right) Example trace showing that continuous 532 nm illumination inhibits single-unit activity ''in vivo''. Inset, representative single unit event; Green bar, 10 seconds.]] [39] => [[File:Microbial-Light-Activatable-Proton-Pumps-as-Neuronal-Inhibitors-to-Functionally-Dissect-Neuronal-pone.0040937.s007.ogv|upright=1.2|thumb|A nematode expressing the light-sensitive ion channel Mac. Mac is a proton pump originally isolated in the fungus ''Leptosphaeria maculans'' and now expressed in the muscle cells of ''C. elegans'' that opens in response to green light and causes hyperpolarizing inhibition. Of note is the extension in body length that the worm undergoes each time it is exposed to green light, which is presumably caused by Mac's muscle-relaxant effects.{{cite journal | vauthors = Husson SJ, Liewald JF, Schultheis C, Stirman JN, Lu H, Gottschalk A | title = Microbial light-activatable proton pumps as neuronal inhibitors to functionally dissect neuronal networks in C. elegans | journal = PLOS ONE | volume = 7 | issue = 7 | pages = e40937 | year = 2012 | pmid = 22815873 | pmc = 3397962 | doi = 10.1371/journal.pone.0040937 | veditors = Samuel A | doi-access = free | bibcode = 2012PLoSO...740937H }} {{open access}}]] [40] => [[File:A-Cholinergic-Regulated-Circuit-Coordinates-the-Maintenance-and-Bi-Stable-States-of-a-Sensory-Motor-pgen.1001326.s010.ogv|upright=1.2|thumb|A nematode expressing ChR2 in its gubernacular-oblique muscle group responding to stimulation by blue light. Blue light stimulation causes the gubernacular-oblique muscles to repeatedly contract, causing repetitive thrusts of the [[Spicule (nematode)|spicule]], as would be seen naturally during copulation.{{cite journal | vauthors = Liu Y, LeBeouf B, Guo X, Correa PA, Gualberto DG, Lints R, Garcia LR | title = A cholinergic-regulated circuit coordinates the maintenance and bi-stable states of a sensory-motor behavior during Caenorhabditis elegans male copulation | journal = PLOS Genetics | volume = 7 | issue = 3 | pages = e1001326 | date = March 2011 | pmid = 21423722 | pmc = 3053324 | doi = 10.1371/journal.pgen.1001326 | veditors = Goodman MB | doi-access = free }} {{open access}}]] [41] => Optogenetics provides millisecond-scale temporal precision which allows the experimenter to keep pace with fast biological information processing (for example, in probing the causal role of specific [[action potential]] patterns in defined neurons). Indeed, to probe the neural code, optogenetics by definition must operate on the millisecond timescale to allow addition or deletion of precise activity patterns within specific cells in the brains of intact animals, including mammals (see '''Figure 1)'''. By comparison, the temporal precision of traditional genetic manipulations (employed to probe the causal role of specific genes within cells, via "loss-of-function" or "gain of function" changes in these genes) is rather slow, from hours or days to months. It is important to also have fast readouts in optogenetics that can keep pace with the optical control. This can be done with electrical recordings ("optrodes") or with reporter proteins that are [[biosensor]]s, where scientists have fused fluorescent proteins to detector proteins. Additionally, beyond its scientific impact optogenetics represents an important case study in the value of both [[Conservation biology|ecological conservation]] (as many of the key tools of optogenetics arise from microbial organisms occupying specialized environmental niches), and in the importance of pure basic science as these [[opsin]]s were studied over decades for their own sake by biophysicists and microbiologists, without involving consideration of their potential value in delivering insights into neuroscience and neuropsychiatric disease.{{cite news |url=https://www.scientificamerican.com/article/optogenetics-controlling/ |title=Optogenetics: Controlling the Brain with Light [Extended Version] | vauthors = Deisseroth K |newspaper=Scientific American |access-date=2016-11-28}} [42] => [43] => '''Light-activated proteins: channels, pumps and enzymes''' [44] => [45] => The hallmark of optogenetics therefore is introduction of fast light-activated channels, pumps, and enzymes that allow temporally precise manipulation of electrical and biochemical events while maintaining cell-type resolution through the use of specific targeting mechanisms. Among the microbial opsins which can be used to investigate the function of neural systems are the [[channelrhodopsin]]s (ChR2, ChR1, VChR1, and SFOs) to excite neurons and [[anion-conducting channelrhodopsin]]s for light-induced inhibition. Indirectly light-controlled [[potassium channel]]s have recently been engineered to prevent action potential generation in neurons during blue light illumination.{{cite journal | vauthors = Beck S, Yu-Strzelczyk J, Pauls D, Constantin OM, Gee CE, Ehmann N, Kittel RJ, Nagel G, Gao S | display-authors = 6 | title = Synthetic Light-Activated Ion Channels for Optogenetic Activation and Inhibition | journal = Frontiers in Neuroscience | volume = 12 | pages = 643 | date = 2018 | pmid = 30333716 | pmc = 6176052 | doi = 10.3389/fnins.2018.00643 | doi-access = free }}{{cite journal| vauthors = Sierra YA, Rost B, Oldani S, Schneider-Warme F, Seifert R, Schmitz D, Hegemann P |date=November 2018 |title=Potassium channel-based two component optogenetic tool for silencing of excitable cells|journal=Biophysical Journal|volume=114 |issue=3 |pages=668a |doi=10.1016/j.bpj.2017.11.3607 |bibcode=2018BpJ...114..668A|doi-access=free |hdl=21.11116/0000-0003-4AEF-E |hdl-access=free }} Light-driven ion pumps are also used to inhibit neuronal activity, e.g. [[halorhodopsin]] (NpHR),{{cite journal | vauthors = Zhao S, Cunha C, Zhang F, Liu Q, Gloss B, Deisseroth K, Augustine GJ, Feng G | display-authors = 6 | title = Improved expression of halorhodopsin for light-induced silencing of neuronal activity | journal = Brain Cell Biology | volume = 36 | issue = 1–4 | pages = 141–154 | date = August 2008 | pmid = 18931914 | pmc = 3057022 | doi = 10.1007/s11068-008-9034-7 }} enhanced halorhodopsins (eNpHR2.0 and eNpHR3.0, see Figure 2),{{cite journal | vauthors = Gradinaru V, Thompson KR, Deisseroth K | title = eNpHR: a Natronomonas halorhodopsin enhanced for optogenetic applications | journal = Brain Cell Biology | volume = 36 | issue = 1–4 | pages = 129–139 | date = August 2008 | pmid = 18677566 | pmc = 2588488 | doi = 10.1007/s11068-008-9027-6 }} [[archaerhodopsin]] (Arch), fungal opsins (Mac) and enhanced bacteriorhodopsin (eBR).{{cite journal | vauthors = Witten IB, Lin SC, Brodsky M, Prakash R, Diester I, Anikeeva P, Gradinaru V, Ramakrishnan C, Deisseroth K | display-authors = 6 | title = Cholinergic interneurons control local circuit activity and cocaine conditioning | journal = Science | volume = 330 | issue = 6011 | pages = 1677–1681 | date = December 2010 | pmid = 21164015 | pmc = 3142356 | doi = 10.1126/science.1193771 | bibcode = 2010Sci...330.1677W }} [46] => [47] => Optogenetic control of well-defined biochemical events within behaving mammals is now also possible. Building on prior work fusing vertebrate [[opsins]] to specific [[G-protein coupled receptors]]{{cite journal | vauthors = Kim JM, Hwa J, Garriga P, Reeves PJ, RajBhandary UL, Khorana HG | title = Light-driven activation of beta 2-adrenergic receptor signaling by a chimeric rhodopsin containing the beta 2-adrenergic receptor cytoplasmic loops | journal = Biochemistry | volume = 44 | issue = 7 | pages = 2284–2292 | date = February 2005 | pmid = 15709741 | doi = 10.1021/bi048328i }} a family of [[chimera (genetics)|chimeric]] single-component optogenetic tools was created that allowed researchers to manipulate within behaving mammals the concentration of defined intracellular messengers such as cAMP and IP3 in targeted cells.{{cite journal | vauthors = Airan RD, Thompson KR, Fenno LE, Bernstein H, Deisseroth K | title = Temporally precise in vivo control of intracellular signalling | journal = Nature | volume = 458 | issue = 7241 | pages = 1025–1029 | date = April 2009 | pmid = 19295515 | doi = 10.1038/nature07926 | s2cid = 4401796 | bibcode = 2009Natur.458.1025A }} Other biochemical approaches to optogenetics (crucially, with tools that displayed low activity in the dark) followed soon thereafter, when optical control over small GTPases and adenylyl cyclase was achieved in cultured cells using novel strategies from several different laboratories.{{cite journal | vauthors = Levskaya A, Weiner OD, Lim WA, Voigt CA | title = Spatiotemporal control of cell signalling using a light-switchable protein interaction | journal = Nature | volume = 461 | issue = 7266 | pages = 997–1001 | date = October 2009 | pmid = 19749742 | pmc = 2989900 | doi = 10.1038/nature08446 | bibcode = 2009Natur.461..997L }}{{cite journal | vauthors = Wu YI, Frey D, Lungu OI, Jaehrig A, Schlichting I, Kuhlman B, Hahn KM | title = A genetically encoded photoactivatable Rac controls the motility of living cells | journal = Nature | volume = 461 | issue = 7260 | pages = 104–108 | date = September 2009 | pmid = 19693014 | pmc = 2766670 | doi = 10.1038/nature08241 | bibcode = 2009Natur.461..104W | author-link5 = Ilme Schlichting }}{{cite journal | vauthors = Yazawa M, Sadaghiani AM, Hsueh B, Dolmetsch RE | title = Induction of protein-protein interactions in live cells using light | journal = Nature Biotechnology | volume = 27 | issue = 10 | pages = 941–945 | date = October 2009 | pmid = 19801976 | doi = 10.1038/nbt.1569 | s2cid = 205274357 }} [[Photoactivated adenylyl cyclase]]s have been discovered in fungi and successfully used to control cAMP levels in mammalian neurons.{{cite journal | vauthors = Stierl M, Stumpf P, Udwari D, Gueta R, Hagedorn R, Losi A, Gärtner W, Petereit L, Efetova M, Schwarzel M, Oertner TG, Nagel G, Hegemann P | display-authors = 6 | title = Light modulation of cellular cAMP by a small bacterial photoactivated adenylyl cyclase, bPAC, of the soil bacterium Beggiatoa | journal = The Journal of Biological Chemistry | volume = 286 | issue = 2 | pages = 1181–1188 | date = January 2011 | pmid = 21030594 | pmc = 3020725 | doi = 10.1074/jbc.M110.185496 | doi-access = free }}{{cite journal | vauthors = Ryu MH, Moskvin OV, Siltberg-Liberles J, Gomelsky M | title = Natural and engineered photoactivated nucleotidyl cyclases for optogenetic applications | journal = The Journal of Biological Chemistry | volume = 285 | issue = 53 | pages = 41501–41508 | date = December 2010 | pmid = 21030591 | pmc = 3009876 | doi = 10.1074/jbc.M110.177600 | doi-access = free }} This emerging repertoire of optogenetic actuators now allows cell-type-specific and temporally precise control of multiple axes of cellular function within intact animals.{{cite journal | vauthors = Lerner TN, Ye L, Deisseroth K | title = Communication in Neural Circuits: Tools, Opportunities, and Challenges | journal = Cell | volume = 164 | issue = 6 | pages = 1136–1150 | date = March 2016 | pmid = 26967281 | pmc = 5725393 | doi = 10.1016/j.cell.2016.02.027 }} [48] => [49] => '''Hardware for light application''' [50] => [51] => Another necessary factor is hardware (e.g. integrated fiberoptic and solid-state light sources) to allow specific cell types, even deep within the brain, to be controlled in freely behaving animals. Most commonly, the latter is now achieved using the fiberoptic-coupled diode technology introduced in 2007,{{cite journal | vauthors = Aravanis AM, Wang LP, Zhang F, Meltzer LA, Mogri MZ, Schneider MB, Deisseroth K | title = An optical neural interface: in vivo control of rodent motor cortex with integrated fiberoptic and optogenetic technology | journal = Journal of Neural Engineering | volume = 4 | issue = 3 | pages = S143–S156 | date = September 2007 | pmid = 17873414 | doi = 10.1088/1741-2560/4/3/S02 | bibcode = 2007JNEng...4S.143A | s2cid = 1488394 }}{{cite journal | vauthors = Adamantidis AR, Zhang F, Aravanis AM, Deisseroth K, de Lecea L | title = Neural substrates of awakening probed with optogenetic control of hypocretin neurons | journal = Nature | volume = 450 | issue = 7168 | pages = 420–424 | date = November 2007 | pmid = 17943086 | pmc = 6744371 | doi = 10.1038/nature06310 | bibcode = 2007Natur.450..420A }}{{cite journal | vauthors = Gradinaru V, Thompson KR, Zhang F, Mogri M, Kay K, Schneider MB, Deisseroth K | title = Targeting and readout strategies for fast optical neural control in vitro and in vivo | journal = The Journal of Neuroscience | volume = 27 | issue = 52 | pages = 14231–14238 | date = December 2007 | pmid = 18160630 | pmc = 6673457 | doi = 10.1523/JNEUROSCI.3578-07.2007 }} though to avoid use of implanted electrodes, researchers have engineered ways to inscribe a "window" made of zirconia that has been modified to be transparent and implanted in mice skulls, to allow optical waves to penetrate more deeply to stimulate or inhibit individual neurons.{{cite journal | vauthors = Damestani Y, Reynolds CL, Szu J, Hsu MS, Kodera Y, Binder DK, Park BH, Garay JE, Rao MP, Aguilar G | display-authors = 6 | title = Transparent nanocrystalline yttria-stabilized-zirconia calvarium prosthesis | journal = Nanomedicine | volume = 9 | issue = 8 | pages = 1135–1138 | date = November 2013 | pmid = 23969102 | doi = 10.1016/j.nano.2013.08.002 | s2cid = 14212180 | url = https://escholarship.org/uc/item/0th8v0p9 }} • Explained by {{cite web |url=http://www.latimes.com/science/sciencenow/la-sci-sn-window-brain-20130903,0,6788242.story |title=A window to the brain? It's here, says UC Riverside team | vauthors = Mohan G |date=September 4, 2013 |website=Los Angeles Times }} To stimulate superficial brain areas such as the cerebral cortex, optical fibers or [[LED]]s can be directly mounted to the skull of the animal. More deeply implanted optical fibers have been used to deliver light to deeper brain areas.{{cite journal | vauthors = Legaria AA, Licholai JA, Kravitz AV | date = January 21, 2021 | title = Fiber photometry does not reflect spiking activity in the striatum | doi = 10.1101/2021.01.20.427525 | biorxiv = 10.1101/2021.01.20.427525| s2cid = 235967184 }} Complementary to fiber-tethered approaches, completely wireless techniques have been developed utilizing wirelessly delivered power to headborne LEDs for unhindered study of complex behaviors in freely behaving organisms.{{cite journal | vauthors = Wentz CT, Bernstein JG, Monahan P, Guerra A, Rodriguez A, Boyden ES | title = A wirelessly powered and controlled device for optical neural control of freely-behaving animals | journal = Journal of Neural Engineering | volume = 8 | issue = 4 | pages = 046021 | date = August 2011 | pmid = 21701058 | pmc = 3151576 | doi = 10.1088/1741-2560/8/4/046021 | bibcode = 2011JNEng...8d6021W }} [52] => [53] => '''Expression of optogenetic actuators''' [54] => [55] => Optogenetics also necessarily includes the development of genetic targeting strategies such as cell-specific promoters or other customized conditionally-active viruses, to deliver the light-sensitive probes to specific populations of neurons in the brain of living animals (e.g. worms, fruit flies, mice, rats, and monkeys). In invertebrates such as worms and fruit flies some amount of [[all-trans-retinal]] (ATR) is supplemented with food. A key advantage of microbial opsins as noted above is that they are fully functional without the addition of exogenous co-factors in vertebrates. [56] => [57] => == Technique == [58] => [[File:Optogenetic stimulation consists of several steps.png|thumb|upright=2|Three primary components in the application of optogenetics are as follows '''(A)''' Identification or synthesis of a light-sensitive protein (opsin) such as channelrhodopsin-2 (ChR2), halorhodopsin (NpHR), etc... '''(B)''' The design of a system to introduce the genetic material containing the opsin into cells for protein expression such as application of Cre recombinase or an adeno-associated-virus '''(C)''' application of light emitting instruments.{{cite journal | vauthors = Pama EA, Colzato LS, Hommel B | title = Optogenetics as a neuromodulation tool in cognitive neuroscience | journal = Frontiers in Psychology | volume = 4 | pages = 610 | date = 2013-01-01 | pmid = 24046763 | pmc = 3764402 | doi = 10.3389/fpsyg.2013.00610 | doi-access = free }}]] [59] => The technique of using optogenetics is flexible and adaptable to the experimenter's needs. Cation-selective channelrhodopsins (e.g. ChR2) are used to excite neurons, anion-conducting channelrhodopsins (e.g. GtACR2) inhibit neuronal activity. Combining these tools into a single construct (e.g. BiPOLES) allows for both inhibition and excitation, depending on the wavelength of illumination.{{Cite journal |last1=Vierock |first1=Johannes |last2=Rodriguez-Rozada |first2=Silvia |last3=Dieter |first3=Alexander |last4=Pieper |first4=Florian |last5=Sims |first5=Ruth |last6=Tenedini |first6=Federico |last7=Bergs |first7=Amelie C. F. |last8=Bendifallah |first8=Imane |last9=Zhou |first9=Fangmin |last10=Zeitzschel |first10=Nadja |last11=Ahlbeck |first11=Joachim |date=2021-07-26 |title=BiPOLES is an optogenetic tool developed for bidirectional dual-color control of neurons |journal=Nature Communications |language=en |volume=12 |issue=1 |pages=4527 |doi=10.1038/s41467-021-24759-5 |issn=2041-1723 |pmc=8313717 |pmid=34312384|bibcode=2021NatCo..12.4527V }} [60] => [61] => Introducing the microbial opsin into a specific subset of cells is challenging. A popular approach is to introduce an engineered viral vector that contains the optogenetic actuator gene attached to a specific [[Promoter (genetics)|promoter]] such as [[CAMK2A|CAMKIIα]], which is active in excitatory neurons. This allows for some level of specificity, preventing e.g. expression in [[glia]] cells.{{cite journal | vauthors = Zhang F, Gradinaru V, Adamantidis AR, Durand R, Airan RD, de Lecea L, Deisseroth K | title = Optogenetic interrogation of neural circuits: technology for probing mammalian brain structures | journal = Nature Protocols | volume = 5 | issue = 3 | pages = 439–456 | date = March 2010 | pmid = 20203662 | pmc = 4503465 | doi = 10.1038/nprot.2009.226 }} [62] => [63] => A more specific approach is based on transgenic "driver" mice which express [[Cre recombinase]], an enzyme that catalyzes recombination between two lox-P sites, in a specific subset of cells, e.g. [[parvalbumin]]-expressing [[interneuron]]s. By introducing an engineered viral vector containing the optogenetic actuator gene in between two lox-P sites, only the cells producing Cre recombinase will express the microbial opsin. This technique has allowed for multiple modified optogenetic actuators to be used without the need to create a whole line of transgenic animals every time a new microbial opsin is needed.{{cite book | vauthors = Zeng H, Madisen L | title = Optogenetics: Tools for Controlling and Monitoring Neuronal Activity | chapter = Mouse transgenic approaches in optogenetics | volume = 196 | pages = 193–213 | date = 2012-09-05 | pmid = 22341327 | pmc = 3433654 | doi = 10.1016/B978-0-444-59426-6.00010-0 | isbn = 9780444594266 | series = Progress in Brain Research }} [64] => [65] => After the introduction and expression of the microbial opsin, a computer-controlled light source has to be optically coupled to the brain region in question. [[Light-emitting diode]]s (LEDs) or fiber-coupled [[diode-pumped solid-state laser]]s (DPSS) are frequently used. Recent advances include the advent of wireless head-mounted devices that apply LEDs to the targeted areas and as a result, give the animals more freedom to move.{{cite journal | vauthors = Warden MR, Cardin JA, Deisseroth K | title = Optical neural interfaces | journal = Annual Review of Biomedical Engineering | volume = 16 | pages = 103–129 | date = July 2014 | pmid = 25014785 | pmc = 4163158 | doi = 10.1146/annurev-bioeng-071813-104733 }}{{cite journal | vauthors = Guru A, Post RJ, Ho YY, Warden MR | title = Making Sense of Optogenetics | journal = The International Journal of Neuropsychopharmacology | volume = 18 | issue = 11 | pages = pyv079 | date = July 2015 | pmid = 26209858 | pmc = 4756725 | doi = 10.1093/ijnp/pyv079 }} [66] => [67] => [[Optical fiber|Fiber]]-based approaches can also be used to combine optical stimulation and [[calcium imaging]]. This enables researchers to visualize and manipulate the activity of single neurons in awake behaving animals.{{cite web |url=https://www.mightexbio.com/products/oasis/oasis-implant/#text-block-16 |title=The Evolution in Freely-Behaving Imaging and Optogenetics Technology |website=OASIS Implant |publisher=Mightex |access-date=2021-06-03}} It is also possible to record from multiple deep brain regions at the same using [[Gradient-index optics|GRIN]] lenses connected via optical fiber to an externally positioned photodetector and photostimulator.{{cite journal | vauthors = Cui G, Jun SB, Jin X, Luo G, Pham MD, Lovinger DM, Vogel SS, Costa RM | display-authors = 6 | title = Deep brain optical measurements of cell type-specific neural activity in behaving mice | journal = Nature Protocols | volume = 9 | issue = 6 | pages = 1213–1228 | date = April 2016 | pmid = 24784819 | pmc = 4100551 | doi = 10.1038/nmeth.3770 }}{{cite journal | vauthors = Cui G, Jun SB, Jin X, Luo G, Pham MD, Lovinger DM, Vogel SS, Costa RM | display-authors = 6 | title = Deep brain optical measurements of cell type-specific neural activity in behaving mice | journal = Nature Protocols | volume = 9 | issue = 6 | pages = 1213–1228 | date = June 2014 | pmid = 24784819 | pmc = 4100551 | doi = 10.1038/nprot.2014.080 }} [68] => [69] => == Technical challenges == [70] => === Selective expression === [71] => [72] => One of the main problems of optogenetics is that not all the cells in question may express the microbial opsin gene at the same level. Thus, even illumination with a defined light intensity will have variable effects on individual cells. Optogenetic stimulation of neurons in the brain is even less controlled as the light intensity drops exponentially from the light source (e.g. implanted optical fiber). [73] => [74] => It remains difficult to target opsin to defined subcellular compartments, e.g. the plasma membrane, synaptic vesicles, or mitochondria.{{cite web| vauthors = Zalocusky KA, Fenno LE, Deisseroth K |date=2013|title=Current Challenges in Optogenetics|url=https://www.sfn.org/~/media/SfN/Documents/Short%20Courses/2013%20Short%20Course%20I/SC1%20Deisseroth.ashx|website=Society for Neuroscience}} Restricting the opsin to specific regions of the plasma membrane such as [[dendrite]]s, [[Soma (biology)|somata]] or [[axon terminal]]s provides a more robust understanding of neuronal circuitry. [75] => [76] => Mathematical modelling shows that selective expression of opsin in specific cell types can dramatically alter the dynamical behavior of the neural circuitry. In particular, optogenetic stimulation that preferentially targets inhibitory cells can transform the excitability of the neural tissue, affecting non-transfected neurons as well.{{cite journal|vauthors=Heitmann S, Rule M, Truccolo W, Ermentrout B|date=January 2017|title=Optogenetic Stimulation Shifts the Excitability of Cerebral Cortex from Type I to Type II: Oscillation Onset and Wave Propagation|journal=PLOS Computational Biology|volume=13|issue=1|pages=e1005349|bibcode=2017PLSCB..13E5349H|doi=10.1371/journal.pcbi.1005349|pmc=5295702|pmid=28118355 |doi-access=free }} [77] => [78] => === Kinetics and synchronization === [79] => [80] => The original channelrhodopsin-2 was slower closing than typical cation channels of cortical neurons, leading to prolonged depolarization and calcium influx.{{Cite journal|last1=Zhang|first1=Yan-Ping|last2=Oertner|first2=Thomas G|date=2007|title=Optical induction of synaptic plasticity using a light-sensitive channel|url=http://www.nature.com/articles/nmeth988|journal=Nature Methods|language=en|volume=4|issue=2|pages=139–141|doi=10.1038/nmeth988|pmid=17195846 |s2cid=17721823 |issn=1548-7091}} Many channelrhodopsin variants with more favorable kinetics have since been engineered.[[Optogenetics#cite note-:0-55|[55]]][56] [81] => [82] => A difference between natural spike patterns and optogenetic activation is that pulsed light stimulation produces synchronous activation of expressing neurons, which removes the possibility of sequential activity in the stimulated population. Therefore, it is difficult to understand how the cells in the population affected communicate with one another or how their phasic properties of activation relate to circuit function. [83] => [84] => Optogenetic activation has been combined with [[functional magnetic resonance imaging]] (ofMRI) to elucidate the [[connectome]], a thorough map of the brain's neural connections.{{cite journal|vauthors=Leergaard TB, Hilgetag CC, Sporns O|date=2012-05-01|title=Mapping the connectome: multi-level analysis of brain connectivity|journal=Frontiers in Neuroinformatics|volume=6|pages=14|doi=10.3389/fninf.2012.00014|pmc=3340894|pmid=22557964|doi-access=free}} Precisely timed optogenetic activation is used to calibrate the delayed hemodynamic signal ([[Blood-oxygen-level-dependent imaging|BOLD]]) fMRI is based on. [85] => [86] => === Light absorption spectrum === [87] => [88] => The opsin proteins currently in use have absorption peaks across the visual spectrum, but remain considerably sensitive to blue light. This spectral overlap makes it very difficult to combine opsin activation with genetically encoded indicators ([[Genetically encoded voltage indicator|GEVIs]], [[Genetically encoded calcium sensor|GECIs]], [[Glutamate-sensitive fluorescent reporter|GluSnFR]], [[synapto-pHluorin]]), most of which need blue light excitation. Opsins with infrared activation would, at a standard irradiance value, increase light penetration and augment resolution through reduction of light scattering. [89] => [90] => === Spatial response === [91] => [92] => Due to scattering, a narrow light beam to stimulate neurons in a patch of neural tissue can evoke a response profile that is much broader than the stimulation beam.{{cite journal | vauthors = Luboeinski J, Tchumatchenko T | title = Nonlinear response characteristics of neural networks and single neurons undergoing optogenetic excitation | journal = Network Neuroscience | volume = 4 | issue = 3 | pages = 852–870 | date = September 2020 | pmid = 33615093 | pmc = 7888483 | doi = 10.1162/netn_a_00154 | doi-access = free }} In this case, neurons may be activated (or inhibited) unintentionally. Computational simulation tools{{cite web | url= https://github.com/ProjectPyRhO/PyRhO |title= PyRhO: a virtual optogenetics laboratory | website=GitHub }}{{cite web | url= https://github.com/jlubo/nn-lightchannels-sim |title= Simulation tool for neural networks and single neurons with light-sensitive channels | website=GitHub }} are used to estimate the volume of stimulated tissue for different wavelengths of light. [93] => [94] => ==Applications== [95] => The field of optogenetics has furthered the fundamental scientific understanding of how specific cell types contribute to the function of biological tissues such as neural circuits ''in vivo''. On the clinical side, optogenetics-driven research has led to insights into [https://www.sciencedirect.com/science/article/pii/S037859552300223X?via%3Dihub restoring with light],{{cite journal |last1=Azees |first1=Ajmal |title=Spread of activation and interaction between channels with multi-channel optogenetic stimulation in the mouse cochlea |journal=Hearing Research |date=December 2023 |volume=440 |doi=10.1016/j.heares.2023.108911 |pmid=37977051 |doi-access=free }} [[Parkinson's disease]]{{cite journal | vauthors = Kravitz AV, Freeze BS, Parker PR, Kay K, Thwin MT, Deisseroth K, Kreitzer AC | title = Regulation of parkinsonian motor behaviours by optogenetic control of basal ganglia circuitry | journal = Nature | volume = 466 | issue = 7306 | pages = 622–626 | date = July 2010 | pmid = 20613723 | pmc = 3552484 | doi = 10.1038/nature09159 | bibcode = 2010Natur.466..622K }}{{cite journal | vauthors = Gradinaru V, Mogri M, Thompson KR, Henderson JM, Deisseroth K | title = Optical deconstruction of parkinsonian neural circuitry | journal = Science | volume = 324 | issue = 5925 | pages = 354–359 | date = April 2009 | pmid = 19299587 | pmc = 6744370 | doi = 10.1126/science.1167093 | citeseerx = 10.1.1.368.668 | bibcode = 2009Sci...324..354G }} and other neurological and psychiatric disorders such as [[autism]], [[Schizophrenia]], [[drug abuse]], anxiety, and [[Major depressive disorder|depression]].{{cite journal | vauthors = Cardin JA, Carlén M, Meletis K, Knoblich U, Zhang F, Deisseroth K, Tsai LH, Moore CI | display-authors = 6 | title = Driving fast-spiking cells induces gamma rhythm and controls sensory responses | journal = Nature | volume = 459 | issue = 7247 | pages = 663–667 | date = June 2009 | pmid = 19396156 | pmc = 3655711 | doi = 10.1038/nature08002 | bibcode = 2009Natur.459..663C }}{{cite journal | vauthors = Sohal VS, Zhang F, Yizhar O, Deisseroth K | title = Parvalbumin neurons and gamma rhythms enhance cortical circuit performance | journal = Nature | volume = 459 | issue = 7247 | pages = 698–702 | date = June 2009 | pmid = 19396159 | pmc = 3969859 | doi = 10.1038/nature07991 | bibcode = 2009Natur.459..698S }}{{cite journal | vauthors = Tsai HC, Zhang F, Adamantidis A, Stuber GD, Bonci A, de Lecea L, Deisseroth K | title = Phasic firing in dopaminergic neurons is sufficient for behavioral conditioning | journal = Science | volume = 324 | issue = 5930 | pages = 1080–1084 | date = May 2009 | pmid = 19389999 | pmc = 5262197 | doi = 10.1126/science.1168878 | bibcode = 2009Sci...324.1080T }} An experimental treatment for blindness involves a channel rhodopsin expressed in [[Retinal ganglion cell|ganglion cells]], stimulated with light patterns from engineered goggles.{{cite news | vauthors = Zimmer C |title=Scientists Partially Restored a Blind Man's Sight With New Gene Therapy |url=https://www.nytimes.com/2021/05/24/science/blindness-therapy-optogenetics.html |access-date=25 May 2021 |work=[[The New York Times]] |date=24 May 2021}}{{cite journal | vauthors = Sahel JA, Boulanger-Scemama E, Pagot C, Arleo A, Galluppi F, Martel JN, Esposti SD, Delaux A, de Saint Aubert JB, de Montleau C, Gutman E, Audo I, Duebel J, Picaud S, Dalkara D, Blouin L, Taiel M, Roska B | display-authors = 6 | title = Partial recovery of visual function in a blind patient after optogenetic therapy | journal = Nature Medicine | volume = 27 | issue = 7 | pages = 1223–1229 | date = July 2021 | pmid = 34031601 | doi = 10.1038/s41591-021-01351-4 | doi-access = free }} [96] => [97] => ===Identification of particular neurons and networks=== [98] => [99] => ====Amygdala==== [100] => Optogenetic approaches have been used to map neural circuits in the [[amygdala]] that contribute to [[fear conditioning]].{{cite journal | vauthors = Haubensak W, Kunwar PS, Cai H, Ciocchi S, Wall NR, Ponnusamy R, Biag J, Dong HW, Deisseroth K, Callaway EM, Fanselow MS, Lüthi A, Anderson DJ | display-authors = 6 | title = Genetic dissection of an amygdala microcircuit that gates conditioned fear | journal = Nature | volume = 468 | issue = 7321 | pages = 270–276 | date = November 2010 | pmid = 21068836 | pmc = 3597095 | doi = 10.1038/nature09553 | bibcode = 2010Natur.468..270H }}{{cite journal | vauthors = Johansen JP, Hamanaka H, Monfils MH, Behnia R, Deisseroth K, Blair HT, LeDoux JE | title = Optical activation of lateral amygdala pyramidal cells instructs associative fear learning | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 107 | issue = 28 | pages = 12692–12697 | date = July 2010 | pmid = 20615999 | pmc = 2906568 | doi = 10.1073/pnas.1002418107 | doi-access = free | bibcode = 2010PNAS..10712692J }}{{cite journal | vauthors = Jasnow AM, Ehrlich DE, Choi DC, Dabrowska J, Bowers ME, McCullough KM, Rainnie DG, Ressler KJ | display-authors = 6 | title = Thy1-expressing neurons in the basolateral amygdala may mediate fear inhibition | journal = The Journal of Neuroscience | volume = 33 | issue = 25 | pages = 10396–10404 | date = June 2013 | pmid = 23785152 | pmc = 3685835 | doi = 10.1523/JNEUROSCI.5539-12.2013 }}{{cite journal | vauthors = Dias BG, Banerjee SB, Goodman JV, Ressler KJ | title = Towards new approaches to disorders of fear and anxiety | journal = Current Opinion in Neurobiology | volume = 23 | issue = 3 | pages = 346–352 | date = June 2013 | pmid = 23402950 | pmc = 3672317 | doi = 10.1016/j.conb.2013.01.013 }} One such example of a neural circuit is the connection made from the [[basolateral amygdala]] to the dorsal-medial prefrontal cortex where [[Neural oscillation|neuronal oscillations]] of 4 Hz have been observed in correlation to fear induced freezing behaviors in mice. Transgenic mice were introduced with channelrhodoposin-2 attached with a [[parvalbumin]]-Cre promoter that selectively infected interneurons located both in the basolateral amygdala and the dorsal-medial prefrontal cortex responsible for the 4 Hz oscillations. The interneurons were optically stimulated generating a freezing behavior and as a result provided evidence that these 4 Hz oscillations may be responsible for the basic fear response produced by the neuronal populations along the dorsal-medial prefrontal cortex and basolateral amygdala.{{cite journal | vauthors = Karalis N, Dejean C, Chaudun F, Khoder S, Rozeske RR, Wurtz H, Bagur S, Benchenane K, Sirota A, Courtin J, Herry C | display-authors = 6 | title = 4-Hz oscillations synchronize prefrontal-amygdala circuits during fear behavior | journal = Nature Neuroscience | volume = 19 | issue = 4 | pages = 605–612 | date = April 2016 | pmid = 26878674 | pmc = 4843971 | doi = 10.1038/nn.4251 }} [101] => [102] => ====Olfactory bulb==== [103] => Optogenetic activation of olfactory sensory neurons was critical for demonstrating timing in odor processing{{cite journal | vauthors = Shusterman R, Smear MC, Koulakov AA, Rinberg D | title = Precise olfactory responses tile the sniff cycle | journal = Nature Neuroscience | volume = 14 | issue = 8 | pages = 1039–1044 | date = July 2011 | pmid = 21765422 | doi = 10.1038/nn.2877 | s2cid = 5194595 }} and for mechanism of neuromodulatory mediated [[Olfaction|olfactory]] guided behaviors (e.g. [[aggression]], [[mating]]){{cite journal | vauthors = Smith RS, Hu R, DeSouza A, Eberly CL, Krahe K, Chan W, Araneda RC | title = Differential Muscarinic Modulation in the Olfactory Bulb | journal = The Journal of Neuroscience | volume = 35 | issue = 30 | pages = 10773–10785 | date = July 2015 | pmid = 26224860 | pmc = 4518052 | doi = 10.1523/JNEUROSCI.0099-15.2015 }} In addition, with the aid of optogenetics, evidence has been reproduced to show that the "afterimage" of odors is concentrated more centrally around the olfactory bulb rather than on the periphery where the olfactory receptor neurons would be located. Transgenic mice infected with channel-rhodopsin Thy1-ChR2, were stimulated with a 473 nm laser transcranially positioned over the dorsal section of the olfactory bulb. Longer photostimulation of [[Olfactory bulb mitral cell|mitral]] cells in the olfactory bulb led to observations of longer lasting neuronal activity in the region after the photostimulation had ceased, meaning the olfactory sensory system is able to undergo long term changes and recognize differences between old and new odors.{{cite journal | vauthors = Patterson MA, Lagier S, Carleton A | title = Odor representations in the olfactory bulb evolve after the first breath and persist as an odor afterimage | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 110 | issue = 35 | pages = E3340–E3349 | date = August 2013 | pmid = 23918364 | pmc = 3761593 | doi = 10.1073/pnas.1303873110 | doi-access = free | bibcode = 2013PNAS..110E3340P }} [104] => [105] => ====Nucleus accumbens==== [106] => Optogenetics, freely moving mammalian behavior, ''in vivo'' electrophysiology, and [[slice preparation|slice physiology]] have been integrated to probe the [[acetylcholine|cholinergic]] [[interneuron]]s of the [[nucleus accumbens]] by direct excitation or inhibition. Despite representing less than 1% of the total population of accumbal neurons, these cholinergic cells are able to control the activity of the [[dopamine]]rgic terminals that innervate medium spiny neurons (MSNs) in the nucleus accumbens.{{cite journal | vauthors = Tecuapetla F, Patel JC, Xenias H, English D, Tadros I, Shah F, Berlin J, Deisseroth K, Rice ME, Tepper JM, Koos T | display-authors = 6 | title = Glutamatergic signaling by mesolimbic dopamine neurons in the nucleus accumbens | journal = The Journal of Neuroscience | volume = 30 | issue = 20 | pages = 7105–7110 | date = May 2010 | pmid = 20484653 | pmc = 3842465 | doi = 10.1523/JNEUROSCI.0265-10.2010 }} These accumbal MSNs are known to be involved in the [[mesolimbic pathway|neural pathway]] through which [[cocaine]] exerts its effects, because decreasing cocaine-induced changes in the activity of these neurons has been shown to inhibit cocaine [[classical conditioning|conditioning]]. The few cholinergic neurons present in the nucleus accumbens may prove viable targets for [[pharmacotherapy]] in the treatment of [[cocaine dependence]] [107] => [108] => ====Prefrontal cortex==== [109] => [[File:Optogenetics imetronic.JPG|upright=1.25|thumb|Cages for rat equipped with optogenetic LED commutators which permit ''in vivo'' study of animal behavior during optogenetic stimulations]] [110] => ''In vivo'' and ''in vitro'' recordings from the University of Colorado, Boulder Optophysiology Laboratory of Donald C. Cooper Ph.D. showing individual CAMKII AAV-ChR2 expressing [[pyramidal neuron]]s within the prefrontal cortex that demonstrated high fidelity action potential output with short pulses of blue light at 20 Hz ('''Figure 1''').{{cite journal | vauthors = Baratta MV, Nakamura S, Dobelis P, Pomrenze MB, Dolzani SD, Cooper DC | title = Optogenetic control of genetically-targeted pyramidal neuron activity in prefrontal cortex | journal = Nature Precedings | date = 2 April 2012 | url = http://precedings.nature.com/documents/7102/version/1/files/npre20127102-1.pdf | bibcode = 2012arXiv1204.0710B | arxiv = 1204.0710 | doi = 10.1038/npre.2012.7102.1 | s2cid = 31641314 }} [111] => [112] => '''Motor cortex''' [113] => [114] => ''In vivo'' repeated optogenetic stimulation in healthy animals was able to eventually induce seizures.{{cite journal | vauthors = Cela E, McFarlan AR, Chung AJ, Wang T, Chierzi S, Murai KK, Sjöström PJ | title = An Optogenetic Kindling Model of Neocortical Epilepsy | journal = Scientific Reports | volume = 9 | issue = 1 | pages = 5236 | date = March 2019 | pmid = 30918286 | pmc = 6437216 | doi = 10.1038/s41598-019-41533-2 | bibcode = 2019NatSR...9.5236C }} This model has been termed optokindling. [115] => [116] => '''Piriform cortex''' [117] => [118] => ''In vivo'' repeated optogenetic stimulation of pyramidal cells of the piriform cortex in healthy animals was able to eventually induce seizures.{{cite journal | vauthors = Ryu B, Nagappan S, Santos-Valencia F, Lee P, Rodriguez E, Lackie M, Takatoh J, Franks KM | display-authors = 6 | title = Chronic loss of inhibition in piriform cortex following brief, daily optogenetic stimulation | journal = Cell Reports | volume = 35 | issue = 3 | pages = 109001 | date = April 2021 | pmid = 33882304 | pmc = 8102022 | doi = 10.1016/j.celrep.2021.109001 | doi-access = free }} ''In vitro'' studies have revealed a loss of feedback inhibition in the piriform circuit due to impaired GABA synthesis. [119] => [120] => ====Heart==== [121] => Optogenetics was applied on atrial [[cardiomyocytes]] to end spiral wave [[arrhythmias]], found to occur in [[atrial fibrillation]], with light.{{cite journal | vauthors = Bingen BO, Engels MC, Schalij MJ, Jangsangthong W, Neshati Z, Feola I, Ypey DL, Askar SF, Panfilov AV, Pijnappels DA, de Vries AA | display-authors = 6 | title = Light-induced termination of spiral wave arrhythmias by optogenetic engineering of atrial cardiomyocytes | journal = Cardiovascular Research | volume = 104 | issue = 1 | pages = 194–205 | date = October 2014 | pmid = 25082848 | doi = 10.1093/cvr/cvu179 | doi-access = free }} This method is still in the development stage. A recent study explored the possibilities of optogenetics as a method to correct for arrythmias and resynchronize cardiac pacing. The study introduced channelrhodopsin-2 into cardiomyocytes in ventricular areas of hearts of transgenic mice and performed ''in vitro'' studies of photostimulation on both open-cavity and closed-cavity mice. Photostimulation led to increased activation of cells and thus increased ventricular contractions resulting in increasing heart rates. In addition, this approach has been applied in cardiac resynchronization therapy ([[Cardiac resynchronization therapy|CRT]]) as a new biological pacemaker as a substitute for electrode based-CRT.{{cite journal | vauthors = Nussinovitch U, Gepstein L | title = Optogenetics for in vivo cardiac pacing and resynchronization therapies | journal = Nature Biotechnology | volume = 33 | issue = 7 | pages = 750–754 | date = July 2015 | pmid = 26098449 | doi = 10.1038/nbt.3268 | s2cid = 1794556 }} Lately, optogenetics has been used in the heart to defibrillate ventricular arrhythmias with local epicardial illumination,{{cite journal | vauthors = Nyns EC, Kip A, Bart CI, Plomp JJ, Zeppenfeld K, Schalij MJ, de Vries AA, Pijnappels DA | display-authors = 6 | title = Optogenetic termination of ventricular arrhythmias in the whole heart: towards biological cardiac rhythm management | journal = European Heart Journal | volume = 38 | issue = 27 | pages = 2132–2136 | date = July 2017 | pmid = 28011703 | pmc = 5837774 | doi = 10.1093/eurheartj/ehw574 }} a generalized whole heart illumination{{cite journal | vauthors = Bruegmann T, Boyle PM, Vogt CC, Karathanos TV, Arevalo HJ, Fleischmann BK, Trayanova NA, Sasse P | display-authors = 6 | title = Optogenetic defibrillation terminates ventricular arrhythmia in mouse hearts and human simulations | journal = The Journal of Clinical Investigation | volume = 126 | issue = 10 | pages = 3894–3904 | date = October 2016 | pmid = 27617859 | pmc = 5096832 | doi = 10.1172/JCI88950 }} or with customized stimulation patterns based on arrhythmogenic mechanisms in order to lower defibrillation energy.{{cite journal | vauthors = Crocini C, Ferrantini C, Coppini R, Scardigli M, Yan P, Loew LM, Smith G, Cerbai E, Poggesi C, Pavone FS, Sacconi L | display-authors = 6 | title = Optogenetics design of mechanistically-based stimulation patterns for cardiac defibrillation | journal = Scientific Reports | volume = 6 | pages = 35628 | date = October 2016 | pmid = 27748433 | pmc = 5066272 | doi = 10.1038/srep35628 | bibcode = 2016NatSR...635628C }} [122] => [123] => ====Spiral ganglion==== [124] => Optogenetic stimulation of the [[spiral ganglion]] in [[deaf]] mice restored auditory activity.{{cite journal | vauthors = Hernandez VH, Gehrt A, Reuter K, Jing Z, Jeschke M, Mendoza Schulz A, Hoch G, Bartels M, Vogt G, Garnham CW, Yawo H, Fukazawa Y, Augustine GJ, Bamberg E, Kügler S, Salditt T, de Hoz L, Strenzke N, Moser T | display-authors = 6 | title = Optogenetic stimulation of the auditory pathway | journal = The Journal of Clinical Investigation | volume = 124 | issue = 3 | pages = 1114–1129 | date = March 2014 | pmid = 24509078 | pmc = 3934189 | doi = 10.1172/JCI69050 }} Optogenetic application onto the [[cochlea]]r region allows for the stimulation or inhibition of the spiral ganglion cells (SGN). In addition, due to the characteristics of the resting potentials of SGN's, different variants of the protein channelrhodopsin-2 have been employed such as Chronos,{{cite journal | vauthors = Keppeler D, Merino RM, Lopez de la Morena D, Bali B, Huet AT, Gehrt A, Wrobel C, Subramanian S, Dombrowski T, Wolf F, Rankovic V, Neef A, Moser T | display-authors = 6 | title = Ultrafast optogenetic stimulation of the auditory pathway by targeting-optimized Chronos | journal = The EMBO Journal | volume = 37 | issue = 24 | pages = e99649 | date = December 2018 | pmid = 30396994 | pmc = 6293277 | doi = 10.15252/embj.201899649 }} CatCh and f-Chrimson.{{cite journal | vauthors = Mager T, Lopez de la Morena D, Senn V, Schlotte J, D Errico A, Feldbauer K, Wrobel C, Jung S, Bodensiek K, Rankovic V, Browne L, Huet A, Jüttner J, Wood PG, Letzkus JJ, Moser T, Bamberg E | display-authors = 6 | title = High frequency neural spiking and auditory signaling by ultrafast red-shifted optogenetics | journal = Nature Communications | volume = 9 | issue = 1 | pages = 1750 | date = May 2018 | pmid = 29717130 | pmc = 5931537 | doi = 10.1038/s41467-018-04146-3 | bibcode = 2018NatCo...9.1750M }} Chronos and CatCh variants are particularly useful in that they have less time spent in their deactivated states, which allow for more activity with less bursts of blue light emitted. Additionally, using engineered red-shifted channels as f-Chrimson allow for stimulation using longer wavelengths, which decreases the potential risks of phototoxicity in the long term without compromising gating speed.{{cite web|title=Engineering long-wavelength light-driven ion channels to hear the light. Atlas of Science|url=https://atlasofscience.org/engineering-long-wavelength-light-driven-ion-channels-to-hear-the-light/|access-date=7 November 2019}} The result being that the LED producing the light would require less energy and the idea of cochlear prosthetics in association with photo-stimulation, would be more feasible.{{cite journal | vauthors = Moser T | title = Optogenetic stimulation of the auditory pathway for research and future prosthetics | journal = Current Opinion in Neurobiology | volume = 34 | pages = 29–36 | date = October 2015 | pmid = 25637880 | doi = 10.1016/j.conb.2015.01.004 | s2cid = 35199775 }} [125] => [126] => ====Brainstem==== [127] => Optogenetic stimulation of a modified red-light excitable channelrhodopsin (ReaChR) expressed in the [[facial motor nucleus]] enabled minimally invasive activation of [[motoneurons]] effective in driving whisker movements in mice.{{cite journal | vauthors = Lin JY, Knutsen PM, Muller A, Kleinfeld D, Tsien RY | title = ReaChR: a red-shifted variant of channelrhodopsin enables deep transcranial optogenetic excitation | journal = Nature Neuroscience | volume = 16 | issue = 10 | pages = 1499–1508 | date = October 2013 | pmid = 23995068 | pmc = 3793847 | doi = 10.1038/nn.3502 }} One novel study employed optogenetics on the [[Dorsal raphe nucleus|Dorsal Raphe Nucleus]] to both activate and inhibit dopaminergic release onto the ventral tegmental area. To produce activation transgenic mice were infected with channelrhodopsin-2 with a TH-Cre promoter and to produce inhibition the [[Hyperpolarization (biology)|hyperpolarizing]] opsin NpHR was added onto the TH-Cre promoter. Results showed that optically activating dopaminergic neurons led to an increase in social interactions, and their inhibition decreased the need to socialize only after a period of isolation.{{cite journal | vauthors = Matthews GA, Nieh EH, Vander Weele CM, Halbert SA, Pradhan RV, Yosafat AS, Glober GF, Izadmehr EM, Thomas RE, Lacy GD, Wildes CP, Ungless MA, Tye KM | display-authors = 6 | title = Dorsal Raphe Dopamine Neurons Represent the Experience of Social Isolation | journal = Cell | volume = 164 | issue = 4 | pages = 617–631 | date = February 2016 | pmid = 26871628 | pmc = 4752823 | doi = 10.1016/j.cell.2015.12.040 }} [128] => [129] => ==== Visual system ==== [130] => Studying the visual system using optogenetics can be challenging. Indeed, the light used for optogenetic control may lead to the activation of photoreceptors, as a result of the proximity between primary visual circuits and these photoreceptors. In this case, spatial selectivity is difficult to achieve (particularly in the case of the fly optic lobe). Thus, the study of the visual system requires spectral separation, using [[Light-gated ion channel|channels]] that are activated by different wavelengths of light than rhodopsins within the photoreceptors (peak activation at 480 nm for Rhodopsin 1 in ''[[Drosophila melanogaster|Drosophila]]''). Red-shifted CsChrimson{{cite journal | vauthors = Klapoetke NC, Murata Y, Kim SS, Pulver SR, Birdsey-Benson A, Cho YK, Morimoto TK, Chuong AS, Carpenter EJ, Tian Z, Wang J, Xie Y, Yan Z, Zhang Y, Chow BY, Surek B, Melkonian M, Jayaraman V, Constantine-Paton M, Wong GK, Boyden ES | display-authors = 6 | title = Independent optical excitation of distinct neural populations | journal = Nature Methods | volume = 11 | issue = 3 | pages = 338–346 | date = March 2014 | pmid = 24509633 | pmc = 3943671 | doi = 10.1038/nmeth.2836 }} or bistable Channelrhodopsin{{cite journal | vauthors = Berndt A, Yizhar O, Gunaydin LA, Hegemann P, Deisseroth K | title = Bi-stable neural state switches | journal = Nature Neuroscience | volume = 12 | issue = 2 | pages = 229–234 | date = February 2009 | pmid = 19079251 | doi = 10.1038/nn.2247 | s2cid = 15125498 }} are used for optogenetic activation of neurons (i.e. [[depolarization]]), as both allow spectral separation. In order to achieve neuronal silencing (i.e. [[Hyperpolarization (biology)|hyperpolarization]]), an anion channelrhodopsin discovered in the cryptophyte algae species ''[[Guillardia|Guillardia theta]]'' (named GtACR1).{{cite journal | vauthors = Govorunova EG, Sineshchekov OA, Janz R, Liu X, Spudich JL | title = NEUROSCIENCE. Natural light-gated anion channels: A family of microbial rhodopsins for advanced optogenetics | journal = Science | volume = 349 | issue = 6248 | pages = 647–650 | date = August 2015 | pmid = 26113638 | pmc = 4764398 | doi = 10.1126/science.aaa7484 }} can be used. GtACR1 is more light sensitive than other inhibitory channels such as the Halorhodopsin class of chlorid pumps and imparts a strong conductance. As its activation peak (515 nm) is close to that of Rhodopsin 1, it is necessary to carefully calibrate the optogenetic illumination as well as the visual stimulus. The factors to take into account are the wavelength of the optogenetic illumination (possibly higher than the activation peak of GtACR1), the size of the stimulus (in order to avoid the activation of the channels by the stimulus light) and the intensity of the optogenetic illumination. It has been shown that GtACR1 can be a useful inhibitory tool in optogenetic study of ''[[Drosophila melanogaster|Drosophila]]'''s visual system by silencing T4/T5 neurons expression.{{cite journal | vauthors = Mauss AS, Busch C, Borst A | title = Optogenetic Neuronal Silencing in Drosophila during Visual Processing | journal = Scientific Reports | volume = 7 | issue = 1 | pages = 13823 | date = October 2017 | pmid = 29061981 | pmc = 5653863 | doi = 10.1038/s41598-017-14076-7 | bibcode = 2017NatSR...713823M }} These studies can also be led on intact behaving animals, for instance to probe [[optomotor response]]. [131] => [132] => ==== Sensorimotor system ==== [133] => Optogenetically inhibiting or activating neurons tests their necessity and sufficiency, respectively, in generating a behavior.{{Cite journal|last1=Portugues|first1=Ruben|last2=Severi|first2=Kristen E|last3=Wyart|first3=Claire|last4=Ahrens|first4=Misha B|date=2013-02-01|title=Optogenetics in a transparent animal: circuit function in the larval zebrafish|url=https://www.sciencedirect.com/science/article/pii/S0959438812001638|journal=Current Opinion in Neurobiology|series=Neurogenetics|language=en|volume=23|issue=1|pages=119–126|doi=10.1016/j.conb.2012.11.001|pmid=23246238|s2cid=19906279|issn=0959-4388}} Using this approach, researchers can dissect the neural circuitry controlling motor output. By perturbing neurons at various places in the sensorimotor system, researchers have learned about the role of descending neurons in eliciting stereotyped behaviors,{{Cite journal|last1=Cande|first1=Jessica|last2=Namiki|first2=Shigehiro|last3=Qiu|first3=Jirui|last4=Korff|first4=Wyatt|last5=Card|first5=Gwyneth M|last6=Shaevitz|first6=Joshua W|last7=Stern|first7=David L|last8=Berman|first8=Gordon J|date=2018-06-26|editor-last=Scott|editor-first=Kristin|title=Optogenetic dissection of descending behavioral control in Drosophila|journal=eLife|volume=7|pages=e34275|doi=10.7554/eLife.34275|pmid=29943729|pmc=6031430|issn=2050-084X |doi-access=free }} how localized tactile sensory input{{Cite journal|last1=DeAngelis|first1=Brian D|last2=Zavatone-Veth|first2=Jacob A|last3=Gonzalez-Suarez|first3=Aneysis D|last4=Clark|first4=Damon A|date=2020-04-22|editor-last=Calabrese|editor-first=Ronald L|title=Spatiotemporally precise optogenetic activation of sensory neurons in freely walking Drosophila|journal=eLife|volume=9|pages=e54183|doi=10.7554/eLife.54183|pmid=32319425|pmc=7198233|issn=2050-084X |doi-access=free }} and activity of interneurons{{Cite journal|last1=Bidaye|first1=Salil S.|last2=Laturney|first2=Meghan|last3=Chang|first3=Amy K.|last4=Liu|first4=Yuejiang|last5=Bockemühl|first5=Till|last6=Büschges|first6=Ansgar|last7=Scott|first7=Kristin|date=2020-11-11|title=Two Brain Pathways Initiate Distinct Forward Walking Programs in Drosophila|journal=Neuron|language=English|volume=108|issue=3|pages=469–485.e8|doi=10.1016/j.neuron.2020.07.032|issn=0896-6273|pmid=32822613|pmc=9435592 |s2cid=221198570}} alters locomotion, and the role of [[Purkinje cell]]s in generating and modulating movement.{{Cite journal|last1=Heiney|first1=Shane A.|last2=Kim|first2=Jinsook|last3=Augustine|first3=George J.|last4=Medina|first4=Javier F.|date=2014-02-05|title=Precise Control of Movement Kinematics by Optogenetic Inhibition of Purkinje Cell Activity|url=https://www.jneurosci.org/content/34/6/2321|journal=Journal of Neuroscience|language=en|volume=34|issue=6|pages=2321–2330|doi=10.1523/JNEUROSCI.4547-13.2014|issn=0270-6474|pmid=24501371|pmc=3913874}} This is a powerful technique for understanding the neural underpinnings of [[animal locomotion]] and movement more broadly. [134] => [135] => ===Precise temporal control of interventions=== [136] => The currently available optogenetic actuators allow for the accurate temporal control of the required intervention (i.e. inhibition or excitation of the target neurons) with precision routinely going down to the millisecond level.{{cite journal | vauthors = Solari N, Sviatkó K, Laszlovszky T, Hegedüs P, Hangya B | title = Open Source Tools for Temporally Controlled Rodent Behavior Suitable for Electrophysiology and Optogenetic Manipulations | journal = Frontiers in Systems Neuroscience | volume = 12 | pages = 18 | date = May 2018 | pmid = 29867383 | pmc = 5962774 | doi = 10.3389/fnsys.2018.00018 | doi-access = free }} The temporal precision varies, however, across optogenetic actuators,{{cite journal | vauthors = Lin JY | title = A user's guide to channelrhodopsin variants: features, limitations and future developments | journal = Experimental Physiology | volume = 96 | issue = 1 | pages = 19–25 | date = January 2011 | pmid = 20621963 | pmc = 2995811 | doi = 10.1113/expphysiol.2009.051961 }} and depends on the frequency and intensity of the stimulation. [137] => [138] => Experiments can now be devised where the light used for the intervention is triggered by a particular element of behavior (to inhibit the behavior), a particular unconditioned stimulus (to associate something to that stimulus) or a particular oscillatory event in the brain (to inhibit the event).{{Cite journal|last1=Grosenick|first1=Logan|last2=Marshel|first2=James H.|last3=Deisseroth|first3=Karl|date=2015-04-08|title=Closed-Loop and Activity-Guided Optogenetic Control|journal=Neuron|language=en|volume=86|issue=1|pages=106–139|doi=10.1016/j.neuron.2015.03.034|pmid=25856490|pmc=4775736|issn=0896-6273}}{{Cite journal|last1=Armstrong|first1=Caren|last2=Krook-Magnuson|first2=Esther|last3=Oijala|first3=Mikko|last4=Soltesz|first4=Ivan|date=2013|title=Closed-loop optogenetic intervention in mice|journal=Nature Protocols|language=en|volume=8|issue=8|pages=1475–1493|doi=10.1038/nprot.2013.080|pmid=23845961|pmc=3988315|issn=1750-2799}} This kind of approach has already been used in several brain regions: [139] => [140] => ====Hippocampus==== [141] => [[Sharp waves and ripples|Sharp waves and ripple complexes]] (SWRs) are distinct high frequency oscillatory events in the [[hippocampus]] thought to play a role in memory formation and consolidation. These events can be readily detected by following the oscillatory cycles of the on-line recorded [[local field potential]]. In this way the onset of the event can be used as a trigger signal for a light flash that is guided back into the hippocampus to inhibit neurons specifically during the SWRs and also to optogenetically inhibit the oscillation itself.{{cite journal | vauthors = Kovács KA, O'Neill J, Schoenenberger P, Penttonen M, Ranguel Guerrero DK, Csicsvari J | title = Optogenetically Blocking Sharp Wave Ripple Events in Sleep Does Not Interfere with the Formation of Stable Spatial Representation in the CA1 Area of the Hippocampus | journal = PLOS ONE | volume = 11 | issue = 10 | pages = e0164675 | date = 19 Nov 2016 | pmid = 27760158 | pmc = 5070819 | doi = 10.1371/journal.pone.0164675 | doi-access = free | bibcode = 2016PLoSO..1164675K }} These kinds of "closed-loop" experiments are useful to study SWR complexes and their role in memory. [142] => [143] => === Cellular biology/cell signaling pathways === [144] => [[File:Optogenetic-control-of-cellular-forces-and-mechanotransduction-ncomms14396-s12.ogv|thumb|upright=2.75|Optogenetic control of cellular forces and induction of mechanotransduction.{{cite journal | vauthors = Valon L, Marín-Llauradó A, Wyatt T, Charras G, Trepat X | title = Optogenetic control of cellular forces and mechanotransduction | journal = Nature Communications | volume = 8 | pages = 14396 | date = February 2017 | pmid = 28186127 | pmc = 5309899 | doi = 10.1038/ncomms14396 | bibcode = 2017NatCo...814396V }} Pictured cells receive an hour of imaging concurrent with blue light that pulses every 60 seconds. This is also indicated when the blue point flashes onto the image. The cell relaxes for an hour without light activation and then this cycle repeats again. The square inset magnifies the cell's nucleus.]] [145] => Analogously to how natural light-gated ion channels such as channelrhodopsin-2 allows optical control of ion flux, which is especially useful in neuroscience, natural light-controlled signal transduction proteins also allow optical control of biochemical pathways, including both second-messenger generation and protein-protein interactions, which is especially useful in studying cell and developmental biology.{{cite journal | vauthors = Khamo JS, Krishnamurthy VV, Sharum SR, Mondal P, Zhang K | title = Applications of Optobiology in Intact Cells and Multicellular Organisms | journal = Journal of Molecular Biology | volume = 429 | issue = 20 | pages = 2999–3017 | date = October 2017 | pmid = 28882542 | doi = 10.1016/j.jmb.2017.08.015 }} In 2002, the first example of using photoproteins from another organism for controlling a biochemical pathway was demonstrated using the light-induced interaction between plant phytochrome and phytochrome-interacting factor (PIF) to control gene transcription in yeast. By fusing phytochrome to a DNA-binding domain and PIF to a transcriptional activation domain, transcriptional activation of genes recognized by the DNA-binding domain could be induced by light. This study anticipated aspects of the later development of optogenetics in the brain, for example, by suggesting that "Directed light delivery by fiber optics has the potential to target selected cells or tissues, even within larger, more-opaque organisms." The literature has been inconsistent as to whether control of cellular biochemistry with photoproteins should be subsumed within the definition of optogenetics, as optogenetics in common usage refers specifically to the control of neuronal firing with opsins,{{cite journal | vauthors = Fenno L, Yizhar O, Deisseroth K | title = The development and application of optogenetics | journal = Annual Review of Neuroscience | volume = 34 | pages = 389–412 | date = 2011 | pmid = 21692661 | pmc = 6699620 | doi = 10.1146/annurev-neuro-061010-113817 }}{{cite web|date=17 December 2010|title=Method of the Year 2010: Optogenetics|url=https://www.youtube.com/watch?v=I64X7vHSHOE|work=Nature Video}}{{Cite web|url=https://pubmed.ncbi.nlm.nih.gov/?term=optogenetics|title=optogenetics - Search Results|website=PubMed|language=en|access-date=2020-02-29}} and as control of neuronal firing with opsins postdates and uses distinct mechanisms from control of cellular biochemistry with photoproteins. [146] => [147] => ==== Photosensitive proteins used in various cell signaling pathways ==== [148] => In addition to phytochromes, which are found in plants and cyanobacteria, LOV domains([[Light-oxygen-voltage-sensing domain]]) from plants and yeast and cryptochrome domains from plants are other natural photosensory domains that have been used for optical control of biochemical pathways in cells.{{cite journal | vauthors = Wittmann T, Dema A, van Haren J | title = Lights, cytoskeleton, action: Optogenetic control of cell dynamics | journal = Current Opinion in Cell Biology | volume = 66 | pages = 1–10 | date = October 2020 | pmid = 32371345 | pmc = 7577957 | doi = 10.1016/j.ceb.2020.03.003 | publisher = Elsevier Ltd. }} In addition, a synthetic photosensory domain has been engineered from the fluorescent protein Dronpa for optical control of biochemical pathways. In photosensory domains, light absorption is either coupled to a change in protein-protein interactions (in the case of phytochromes, some LOV domains, cryptochromes, and Dronpa mutants) or a conformational change that exposes a linked protein segment or alters the activity of a linked protein domain (in the case of phytochromes and some LOV domains). Light-regulated protein-protein interactions can then be used to recruit proteins to DNA, for example to induce gene transcription or DNA modifications, or to the plasma membrane, for example to activate resident signaling proteins.{{cite journal | vauthors = Konermann S, Brigham MD, Trevino A, Hsu PD, Heidenreich M, Cong L, Platt RJ, Scott DA, Church GM, Zhang F | display-authors = 6 | title = Optical control of mammalian endogenous transcription and epigenetic states | journal = Nature | volume = 500 | issue = 7463 | pages = 472–476 | date = August 2013 | pmid = 23877069 | pmc = 3856241 | doi = 10.1038/nature12466 | bibcode = 2013Natur.500..472K }}{{cite journal | vauthors = Leung DW, Otomo C, Chory J, Rosen MK | title = Genetically encoded photoswitching of actin assembly through the Cdc42-WASP-Arp2/3 complex pathway | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 105 | issue = 35 | pages = 12797–12802 | date = September 2008 | pmid = 18728185 | pmc = 2525560 | doi = 10.1073/pnas.0801232105 | doi-access = free | bibcode = 2008PNAS..10512797L }}{{cite journal | vauthors = Toettcher JE, Gong D, Lim WA, Weiner OD | title = Light-based feedback for controlling intracellular signaling dynamics | journal = Nature Methods | volume = 8 | issue = 10 | pages = 837–839 | date = September 2011 | pmid = 21909100 | pmc = 3184382 | doi = 10.1038/nmeth.1700 }}{{cite journal | vauthors = Strickland D, Lin Y, Wagner E, Hope CM, Zayner J, Antoniou C, Sosnick TR, Weiss EL, Glotzer M | display-authors = 6 | title = TULIPs: tunable, light-controlled interacting protein tags for cell biology | journal = Nature Methods | volume = 9 | issue = 4 | pages = 379–384 | date = March 2012 | pmid = 22388287 | pmc = 3444151 | doi = 10.1038/nmeth.1904 }}{{cite journal | vauthors = Idevall-Hagren O, Dickson EJ, Hille B, Toomre DK, De Camilli P | title = Optogenetic control of phosphoinositide metabolism | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 109 | issue = 35 | pages = E2316–E2323 | date = August 2012 | pmid = 22847441 | pmc = 3435206 | doi = 10.1073/pnas.1211305109 | doi-access = free | bibcode = 2012PNAS..109E2316I }} CRY2 also clusters when active, so has been fused with signaling domains and subsequently photoactivated to allow for clustering-based activation.{{cite journal | vauthors = Bugaj LJ, Choksi AT, Mesuda CK, Kane RS, Schaffer DV | title = Optogenetic protein clustering and signaling activation in mammalian cells | journal = Nature Methods | volume = 10 | issue = 3 | pages = 249–252 | date = March 2013 | pmid = 23377377 | doi = 10.1038/nmeth.2360 | s2cid = 8737019 }} The LOV2 domain of ''Avena sativa''(common oat) has been used to expose short peptides or an active protein domain in a light-dependent manner.{{cite journal | vauthors = Lungu OI, Hallett RA, Choi EJ, Aiken MJ, Hahn KM, Kuhlman B | title = Designing photoswitchable peptides using the AsLOV2 domain | journal = Chemistry & Biology | volume = 19 | issue = 4 | pages = 507–517 | date = April 2012 | pmid = 22520757 | pmc = 3334866 | doi = 10.1016/j.chembiol.2012.02.006 }}{{cite journal | vauthors = Wu YI, Frey D, Lungu OI, Jaehrig A, Schlichting I, Kuhlman B, Hahn KM | title = A genetically encoded photoactivatable Rac controls the motility of living cells | journal = Nature | volume = 461 | issue = 7260 | pages = 104–108 | date = September 2009 | pmid = 19693014 | pmc = 2766670 | doi = 10.1038/nature08241 | bibcode = 2009Natur.461..104W }}{{cite journal | vauthors = Smart AD, Pache RA, Thomsen ND, Kortemme T, Davis GW, Wells JA | title = Engineering a light-activated caspase-3 for precise ablation of neurons in vivo | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 114 | issue = 39 | pages = E8174–E8183 | date = September 2017 | pmid = 28893998 | pmc = 5625904 | doi = 10.1073/pnas.1705064114 | bibcode = 2017PNAS..114E8174S | doi-access = free | author-link4 = Tanja Kortemme }} Introduction of this LOV domain into another protein can regulate function through light induced peptide disorder.{{cite journal | vauthors = Dagliyan O, Tarnawski M, Chu PH, Shirvanyants D, Schlichting I, Dokholyan NV, Hahn KM | title = Engineering extrinsic disorder to control protein activity in living cells | journal = Science | volume = 354 | issue = 6318 | pages = 1441–1444 | date = December 2016 | pmid = 27980211 | pmc = 5362825 | doi = 10.1126/science.aah3404 | bibcode = 2016Sci...354.1441D }} The asLOV2 protein, which optogenetically exposes a peptide, has also been used as a scaffold for several synthetic light induced dimerization and light induced dissociation systems (iLID and LOVTRAP, respectively).{{cite journal | vauthors = Guntas G, Hallett RA, Zimmerman SP, Williams T, Yumerefendi H, Bear JE, Kuhlman B | title = Engineering an improved light-induced dimer (iLID) for controlling the localization and activity of signaling proteins | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 112 | issue = 1 | pages = 112–117 | date = January 2015 | pmid = 25535392 | pmc = 4291625 | doi = 10.1073/pnas.1417910112 | doi-access = free | bibcode = 2015PNAS..112..112G }}{{cite journal | vauthors = Wang H, Vilela M, Winkler A, Tarnawski M, Schlichting I, Yumerefendi H, Kuhlman B, Liu R, Danuser G, Hahn KM | display-authors = 6 | title = LOVTRAP: an optogenetic system for photoinduced protein dissociation | journal = Nature Methods | volume = 13 | issue = 9 | pages = 755–758 | date = September 2016 | pmid = 27427858 | pmc = 5137947 | doi = 10.1038/nmeth.3926 }} The systems can be used to control proteins through a protein splitting strategy.{{cite journal | vauthors = van Haren J, Charafeddine RA, Ettinger A, Wang H, Hahn KM, Wittmann T | title = Local control of intracellular microtubule dynamics by EB1 photodissociation | journal = Nature Cell Biology | volume = 20 | issue = 3 | pages = 252–261 | date = March 2018 | pmid = 29379139 | pmc = 5826794 | doi = 10.1038/s41556-017-0028-5 | publisher = Nature Research. }} Photodissociable Dronpa domains have also been used to cage a protein active site in the dark, uncage it after cyan light illumination, and recage it after violet light illumination.{{cite journal | vauthors = Zhou XX, Chung HK, Lam AJ, Lin MZ | title = Optical control of protein activity by fluorescent protein domains | journal = Science | volume = 338 | issue = 6108 | pages = 810–814 | date = November 2012 | pmid = 23139335 | pmc = 3702057 | doi = 10.1126/science.1226854 | bibcode = 2012Sci...338..810Z }} [149] => [150] => ==== Temporal control of signal transduction with light ==== [151] => The ability to optically control signals for various time durations is being explored to elucidate how cell signaling pathways convert signal duration and response to different outputs.{{cite journal | vauthors = Tischer D, Weiner OD | title = Illuminating cell signalling with optogenetic tools | journal = Nature Reviews. Molecular Cell Biology | volume = 15 | issue = 8 | pages = 551–558 | date = August 2014 | pmid = 25027655 | pmc = 4145075 | doi = 10.1038/nrm3837 }} Natural signaling cascades are capable of responding with different outputs to differences in stimulus timing duration and dynamics.{{cite journal | vauthors = Purvis JE, Lahav G | title = Encoding and decoding cellular information through signaling dynamics | journal = Cell | volume = 152 | issue = 5 | pages = 945–956 | date = February 2013 | pmid = 23452846 | pmc = 3707615 | doi = 10.1016/j.cell.2013.02.005 }} For example, treating PC12 cells with epidermal growth factor (EGF, inducing a transient profile of ERK activity) leads to cellular proliferation whereas introduction of nerve growth factor (NGF, inducing a sustained profile of ERK activity) leads to differentiation into neuron-like cells.{{cite journal | vauthors = Santos SD, Verveer PJ, Bastiaens PI | title = Growth factor-induced MAPK network topology shapes Erk response determining PC-12 cell fate | journal = Nature Cell Biology | volume = 9 | issue = 3 | pages = 324–330 | date = March 2007 | pmid = 17310240 | doi = 10.1038/ncb1543 | s2cid = 31709706 }} This behavior was initially characterized using EGF and NGF application, but the finding has been partially replicated with optical inputs.{{cite journal | vauthors = Toettcher JE, Weiner OD, Lim WA | title = Using optogenetics to interrogate the dynamic control of signal transmission by the Ras/Erk module | journal = Cell | volume = 155 | issue = 6 | pages = 1422–1434 | date = December 2013 | pmid = 24315106 | pmc = 3925772 | doi = 10.1016/j.cell.2013.11.004 }} In addition, a rapid negative feedback loop in the RAF-MEK-ERK pathway was discovered using pulsatile activation of a photoswitchable RAF engineered with photodissociable Dronpa domains. [152] => [153] => === Optogenetic noise-photostimulation === [154] => Professor Elias Manjarrez's research group introduced the Optogenetic noise-photostimulation.{{cite journal | vauthors = Huidobro N, Mendez-Fernandez A, Mendez-Balbuena I, Gutierrez R, Kristeva R, Manjarrez E | title = Brownian Optogenetic-Noise-Photostimulation on the Brain Amplifies Somatosensory-Evoked Field Potentials | journal = Frontiers in Neuroscience | volume = 11 | pages = 464 | date = 2017 | pmid = 28912671 | doi = 10.3389/fnins.2017.00464 | pmc = 5583167 | doi-access = free }}{{cite journal | vauthors = Huidobro N, De la Torre-Valdovinos B, Mendez A, Treviño M, Arias-Carrion O, Chavez F, Gutierrez R, Manjarrez E | display-authors = 6 | title = Optogenetic noise-photostimulation on the brain increases somatosensory spike firing responses | journal = Neuroscience Letters | volume = 664 | pages = 51–57 | date = January 2018 | pmid = 29128628 | doi = 10.1016/j.neulet.2017.11.004 | s2cid = 3370851 }}{{cite journal | vauthors = Mabil P, Huidobro N, Torres-Ramirez O, Flores-Hernandez J, Flores A, Gutierrez R, Manjarrez E | title = Noisy Light Augments the Na+ Current in Somatosensory Pyramidal Neurons of Optogenetic Transgenic Mice | journal = Frontiers in Neuroscience | volume = 14 | pages = 490 | date = 2020 | pmid = 32528244 | doi = 10.3389/fnins.2020.00490| pmc=7263390 | doi-access = free }} This is a technique that uses random noisy light to activate neurons expressing ChR2. An optimal level of optogenetic-noise photostimulation on the brain can increase the somatosensory evoked field potentials, the firing frequency response of pyramidal neurons to somatosensory stimulation, and the sodium current amplitude. [155] => [156] => ==Awards== [157] => The powerful impact of optogenetic technology on brain research has been recognized by numerous awards to key players in the field. [158] => [159] => In 2010, Georg Nagel, Peter Hegemann and Ernst Bamberg were awarded the [[Wiley Prize in Biomedical Sciences]][http://eu.wiley.com/WileyCDA/PressRelease/pressReleaseId-67957.html?print=true Ninth Annual Wiley Prize in Biomedical Sciences Awarded to Dr. Peter Hegemann, Dr. Georg Nagel, and Dr. Ernst Bamberg] (wiley.com) and they were also among those awarded the Karl Heinz Beckurts Prize in 2010.{{Cite web|title=Karl Heinz Beckurts-Preis 2010|url=https://www.beckurts-stiftung.de/karl-heinz-beckurts-preis-2010-fuer-dr-stephan-lutgen-dr-adrian-avramescu-und-dr-desiree-queren-sowie-prof-dr-peter-hegemann-prof-dr-georg-nagel-und-prof-dr-ernst-bamberg/|website=Karl Heinz Beckurts Foundation}} In the same year, Karl Deisseroth was awarded the inaugural [[HFSP Nakasone Award]] for "his pioneering work on the development of optogenetic methods for studying the function of neuronal networks underlying behavior".{{Cite web|title=HFSP Nakasone Award 2010|url=https://www.hfsp.org/hfsp-nakasone-award/2010-karl-deisseroth|website=[[Human Frontier Science Program]]}} [160] => [161] => In 2012, Bamberg, Deisseroth, Hegemann and Georg Nagel were awarded the Zülch Prize by the [[Max Planck Society]],{{Cite web|title=International Prize for Translational Neuroscience of the Gertrud Reemtsma Foundation (K.J. Zülch Prize until 2019)|url=https://www.mpg.de/prizes/international-prize-for-translational-neuroscience|website=[[Max Planck Society]]}} and Miesenböck was awarded the Baillet Latour Health Prize for "having pioneered optogenetic approaches to manipulate neuronal activity and to control animal behaviour."{{cite web | title = InBev-Baillet Latour International Health Prize | url = https://www.frs-fnrs.be/docs/Prix/FRS-FNRS_Historical_Baillet_Latour_health_prize.pdf | work = Fonds de la Recherche Scientifique - FNRS }} [162] => [163] => In 2013, Georg Nagel and Hegemann were among those awarded the [[Louis-Jeantet Prize for Medicine]].[https://www.jeantet.ch/en/prix-louis-jeantet/laureats/2018-en/professeurs-peter-hegemann-et-georg-nagel/ Louis-Jeantet Prize] Also that year, year Bamberg, Boyden, Deisseroth, Hegemann, Miesenböck and Georg Nagel were jointly awarded [[Grete Lundbeck European Brain Research Prize|The Brain Prize]] for "their invention and refinement of optogenetics."{{cite web |title=The Brain Prize 2013 |url=http://www.thebrainprize.org/flx/prize_winners/ |access-date=3 October 2013 |archive-url=https://web.archive.org/web/20131004194843/http://www.thebrainprize.org/flx/prize_winners/ |archive-date=4 October 2013 |url-status=dead }}{{cite journal | vauthors = Reiner A, Isacoff EY | title = The Brain Prize 2013: the optogenetics revolution | journal = Trends in Neurosciences | volume = 36 | issue = 10 | pages = 557–560 | date = October 2013 | pmid = 24054067 | doi = 10.1016/j.tins.2013.08.005 | s2cid = 205404606 }} [164] => [165] => In 2017, Deisseroth was awarded the [[Else Kröner-Fresenius Foundation|Else Kröner Fresenius]] Research Prize for "his discoveries in optogenetics and hydrogel-tissue chemistry, as well as his research into the neural circuit basis of depression."{{Cite web|title=Else Kröner Fresenius Prize for Medical Research 2017|url=http://ekfs.de/en/scientific-funding/international-research-prize/else-kroener-fresenius-prize-for-medical-research-2017|website=[[Else Kröner-Fresenius Foundation]]}} [166] => [167] => In 2018, the [[Inamori Foundation]] presented Deisseroth with the [[Kyoto Prize]] for "spearheading optogenetics” and "revolutionizing systems neuroscience research."{{Cite web|title=2018 Kyoto Prize Laureate Karl Deisseroth|url=https://kyotoprize.org/en/laureates/karl_deisseroth/|website=[[Kyoto Prize]]}} [168] => [169] => In 2019, Bamberg, Boyden, Deisseroth, Hegemann, Miesenböck and Georg Nagel were awarded the [[Rumford Prize]] by the [[American Academy of Arts and Sciences]] in recognition of "their extraordinary contributions related to the invention and refinement of optogenetics."{{Cite web|url=https://www.amacad.org/news/rumford-prize-optogenetics|title=Rumford Prize Awarded for the Invention and Refinement of Optogenetics|website=American Academy of Arts & Sciences|date=30 January 2019 |language=en|access-date=2019-03-12}} [170] => [171] => In 2020, Deisseroth was awarded the [[Heineken Prizes|Heineken Prize]] for Medicine from the [[Royal Netherlands Academy of Arts and Sciences]], for developing optogenetics and hydrogel-tissue chemistry.{{Cite web|title=2020 Heineken Prize Laureate Karl Deisseroth|url=https://www.heinekenprizes.org/portfolio-items/karl-deisseroth/|website=[[Heineken Prizes]]}} [172] => [173] => In 2020, Miesenböck, Hegemann and Georg Nagel jointly received the [[Shaw Prize]] in Life Science and Medicine.{{Cite web|title=2020 Shaw Prize Laureates Miesenböck, Hegemann and Georg Nagel|url=https://www.shawprize.org/laureates/life-science-medicine/2020|website=[[Shaw Prize]]}} [174] => [175] => In 2021, Hegemann, Deisseroth and [[Dieter Oesterhelt]] received the [[Albert Lasker Award for Basic Medical Research]]. [176] => [177] => == References == [178] => {{Reflist|32em}} [179] => [180] => == Further reading == [181] => {{refbegin|32em}} [182] => * {{cite book | vauthors = Appasani K |title=Optogenetics: from neuronal function to mapping and disease biology |date=2017 |publisher=Cambridge University Press |location=Cambridge, UK |isbn=978-1-107-05301-4}} [183] => * {{cite journal | vauthors = Banerjee S, Mitra D | title = Structural Basis of Design and Engineering for Advanced Plant Optogenetics | journal = Trends in Plant Science | volume = 25 | issue = 1 | pages = 35–65 | date = January 2020 | pmid = 31699521 | doi = 10.1016/j.tplants.2019.10.002 | s2cid = 207942668 }} [184] => * {{cite journal | vauthors = Hu W, Li Q, Li B, Ma K, Zhang C, Fu X | title = Optogenetics sheds new light on tissue engineering and regenerative medicine | journal = Biomaterials | volume = 227 | pages = 119546 | date = January 2020 | pmid = 31655444 | doi = 10.1016/j.biomaterials.2019.119546 | s2cid = 204918731 }} [185] => * {{cite journal | vauthors = Jarrin S, Finn DP | title = Optogenetics and its application in pain and anxiety research | journal = Neuroscience and Biobehavioral Reviews | volume = 105 | pages = 200–211 | date = October 2019 | pmid = 31421140 | doi = 10.1016/j.neubiorev.2019.08.007 | s2cid = 199577276 }} [186] => * {{cite journal | vauthors = Johnson HE, Toettcher JE | title = Illuminating developmental biology with cellular optogenetics | journal = Current Opinion in Biotechnology | volume = 52 | pages = 42–48 | date = August 2018 | pmid = 29505976 | pmc = 6082700 | doi = 10.1016/j.copbio.2018.02.003 }} [187] => * {{cite journal | vauthors = Krueger D, Izquierdo E, Viswanathan R, Hartmann J, Pallares Cartes C, De Renzis S | title = Principles and applications of optogenetics in developmental biology | journal = Development | volume = 146 | issue = 20 | pages = dev175067 | date = October 2019 | pmid = 31641044 | pmc = 6914371 | doi = 10.1242/dev.175067 }} [188] => * {{cite journal | vauthors = Losi A, Gardner KH, Möglich A | title = Blue-Light Receptors for Optogenetics | journal = Chemical Reviews | volume = 118 | issue = 21 | pages = 10659–10709 | date = November 2018 | pmid = 29984995 | pmc = 6500593 | doi = 10.1021/acs.chemrev.8b00163 }} [189] => * {{cite book | vauthors = Vriz S, Ozawa T |title=Optogenetics: light-driven actuators and light-emitting sensors in cell biology |date=September 2018 |publisher=Royal Society of Chemistry | location = London |isbn=978-1-78801-237-9 | series = Comprehensive Series in Photochemistry and Photobiology | volume = 18 }} [190] => * {{cite journal | vauthors = Wittmann T, Dema A, van Haren J | title = Lights, cytoskeleton, action: Optogenetic control of cell dynamics | journal = Current Opinion in Cell Biology | volume = 66 | pages = 1–10 | date = October 2020 | pmid = 32371345 | pmc = 7577957 | doi = 10.1016/j.ceb.2020.03.003 | publisher = Elsevier Ltd. | doi-access = free }} [191] => [192] => {{refend}} [193] => [194] => == External links == [195] => {{wiktionary | optogenetics}} [196] => * {{cite web | url = https://www.scientifica.uk.com/learning-zone/optogenetics-shedding-light-on-the-brains-secrets | title = Optogenetics: shedding light on the brain's secrets | work = Scientifica }} [197] => * {{cite web | url = https://www.inscopix.com/optogenetics | title = Optogenetics: Integrated Calcium Imaging and Optogenetics | work = Inscopix | date = 6 April 2020 }} [198] => [199] => {{Optogenetics}} [200] => {{BCI}} [201] => [202] => [[Category:Neuroscience]] [203] => [[Category:Biological techniques and tools]] [204] => [[Category:Cybernetics]] [205] => [[Category:Control theory]] [206] => [[Category:Brain–computer interface]] [207] => [[Category:Neuroprosthetics]] [208] => [[Category:Neural engineering]] [209] => [[Category:Articles containing video clips]] [210] => [[Category:Optics]] [] => )
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Optogenetics

Optogenetics is a biological technique to control the activity of neurons or other cell types with light. This is achieved by expression of light-sensitive ion channels, pumps or enzymes specifically in the target cells.

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