Deisseroth, Hegemann & Nagel: Optogenetics, a Light Switch for Nerve Cells

Table of Contents

1. The 2026 Prize and the Three Scientists
2. The Problem: Watching the Brain Was Not Enough
3. A Swimming Alga's Eyespot, 1991–1992
4. Channelrhodopsin: A Light Sensor That Is Also a Channel, 2002–2003
5. Light Switches On a Nerve Cell, 2005
6. Into the Living Brain, 2006–2007
7. How Optogenetics Works, in Plain Language
8. What It Revealed About the Brain and Body
9. In the Clinic: Partial Vision, and Hearing Research
10. Limits and Open Questions
11. Key Research Papers
12. Connections
13. Featured Videos

The 2026 Prize and the Three Scientists

The Nobel Assembly at Karolinska Institutet, which awards the medicine prize, announced the decision on Monday 5 October 2026. The three laureates each hold a one-third share, and the prize amount of 12 million Swedish kronor is shared equally between them. The official record is at nobelprize.org — the Nobel Prize in Physiology or Medicine 2026, with the Assembly's press release and a scientific background written by the Nobel Committee.

• Peter Hegemann (born 1954) received his PhD in 1984 at the Max Planck Institute for Biochemistry in Martinsried, Germany, where the prize-awarded discoveries were made. He is now Hertie Senior Professor of Neuroscience at Humboldt University of Berlin. He did his doctorate with Dieter Oesterhelt, co-discoverer of the light-driven pump bacteriorhodopsin, and then joined the laboratory of Kenneth Foster, who studied how algae respond to light.
• Georg Nagel (born 1953) received his PhD in 1988 at the University of Frankfurt, working under Ernst Bamberg at the Max Planck Institute of Biophysics. After postdoctoral work at Yale and Rockefeller University he returned to Frankfurt as an independent investigator. The prize-awarded discoveries were made at the Max Planck Institute for Biophysics in Frankfurt. He is now Professor of Molecular Plant Physiology at the University of Würzburg.
• Karl Deisseroth (born 1971) received his PhD in 1998 and his MD in 2000 from Stanford University. He trained as a psychiatrist and was setting up his own laboratory at Stanford when he took up channelrhodopsin. He is D.H. Chen Professor and Professor of Bioengineering and of Psychiatry and Behavioral Sciences at the Howard Hughes Medical Institute and Stanford University.

The press release quotes Per Svenningsson, Chair of the Nobel Committee for Physiology or Medicine: “Optogenetics provides opportunities for mapping the brain in a way that we could once only dream of.”

The Committee's scientific background also credits many others. Among them are Ernst Bamberg, co-author of the 2002, 2003 and 2005 papers below; Edward Boyden and Feng Zhang, first authors of the 2005 nerve-cell paper and the 2007 off-switch paper; the groups of John Spudich and Takahashi; and the builders of earlier light-control systems. It places optogenetics in a line of methods that changed neuroscience, after Camillo Golgi's stain, which let Santiago Ramón y Cajal formulate the neuron doctrine (1906 prize), and the patch clamp of Erwin Neher and Bert Sakmann (1991 prize).

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The Problem: Watching the Brain Was Not Enough

By the late twentieth century, researchers knew a great deal about which brain regions take part in which functions. They could record electrical activity, study the effects of brain injuries, give drugs and image the working brain. The Nobel Assembly's press release states the limit plainly: those methods “could not prove causal relationships,” and the picture of the brain they produced was “like a sketch map, full of question marks and unknowns.”

The Committee's scientific background points out that neural activity unfolds in milliseconds, and that neighbouring neurons often drive opposing functions or take part in different behaviours. Electrodes, lesions and drugs could not single out one cell type inside an intact circuit at the speed those circuits work. A 2007 paper from Deisseroth's group noted that stimulating electrodes “remain incapable of reliably targeting specific cell types,” which left “intense debate” over which cells deep brain stimulation recruits.

Francis Crick, co-discoverer of the structure of DNA, had described what was needed. As quoted in the Committee's background, Crick wrote of a method in which “all neurons of just one type could be activated or inactivated, leaving the others more or less unaltered.” He suggested that for switching neurons on and off quickly in an alert animal “the ideal signal would be light,” an idea he acknowledged was “rather far-fetched.” The Committee cites Crick's articles of 1979 and 1999.

Earlier attempts showed both the promise and the obstacles. In 2002, Gero Miesenböck's group made vertebrate nerve cells fire in response to light by co-expressing three fruit-fly photoreceptor genes, a combination they called “chARGe.” Other groups attached light-switchable synthetic chemicals to engineered ion channels. According to the Committee's review, the gene-based systems were too slow, because the signal passed through intermediate steps or depended on diffusion. Both approaches also needed chemicals or several large genes to be delivered into tissue, which complicated their use in intact brains. In the background's words, “A single protein had to do the job,” one that could be delivered as a gene and would turn light directly into an electrical current within milliseconds.

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A Swimming Alga's Eyespot, 1991–1992

The single protein came from an alga. Chlamydomonas reinhardtii is a single-celled green alga that swims toward light using two flagella. It senses light with an eyespot, which the Nobel Committee's popular-science account describes as “a tiny orange dot on the cell's surface that contains a light-capturing molecule, retinal.” In 1984, Kenneth Foster and colleagues showed that the alga's photoreceptor is a rhodopsin, a protein that captures light with retinal. When they gave retinal-like molecules to a blind mutant alga, its normal light responses returned. The colour it responded to best also shifted to match the molecule supplied.

Hegemann set out to learn how the alga responds so quickly. With suction-electrode recordings, he and Hartmann Harz measured the currents that light triggers in the cell. Their 1991 paper in Nature described two distinct light-regulated inward currents, one at the eyespot and one in the region of the flagella, and both depended on calcium. A fuller report in 1992 found that after a flash the eyespot current “rises with no detectable delay in less than 2 ms to the maximum.” It also found that the current's sensitivity to colour peaks at 494 nanometres, closely matching the absorption maximum of rhodopsin.

That speed was the clue. The Committee's popular account compares it with the human eye, where light sets off a chemical chain reaction of many steps that takes at least 10 milliseconds. In the alga, an electrical impulse appeared about half a millisecond after light reached the eyespot. Hegemann's explanation, put forward in the early 1990s, was that a single protein complex both captured the light and acted as an ion channel. The popular account records that the idea met scepticism, because none of the many ion channels then known could react to light on its own.

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Channelrhodopsin: A Light Sensor That Is Also a Channel, 2002–2003

Isolating the protein itself proved hard. Removed from the eyespot, the proteins became unstable and easily damaged. The break came from genetics. Around the turn of the millennium, Japanese researchers made sequences for thousands of Chlamydomonas genes available, and Hegemann's group found two that resembled the genes of known light-capturing proteins. According to the Committee's background, three groups identified these sequences independently: Hegemann's, John Spudich's and a third led by Takahashi. In 2002, Spudich's group used RNA interference to silence each gene in turn. They showed that the two proteins, which they named CSRA and CSRB, generate the alga's photoreceptor currents and act as its receptors for swimming toward light.

What the sequences could not show was how the proteins worked. Hegemann contacted Georg Nagel, an electrophysiologist who studied ion channels and pumps by expressing them in frog egg cells. Nagel injected each gene into eggs of the frog Xenopus laevis, which then made the algal protein and placed it in their outer membrane. In 2002, with Ernst Bamberg, Hegemann and others, he reported in Science on the first protein. Supplied with the light-absorbing molecule all-trans retinal, it produced a light-gated conductance that “shows characteristics of a channel selectively permeable for protons.” The protein's core region alone was enough. It was named channelrhodopsin-1.

The second protein turned out to be the more useful one. In 2003, in the Proceedings of the National Academy of Sciences, Nagel, Hegemann, Bamberg and colleagues reported experiments in frog eggs and in mammalian cells. They showed that channelrhodopsin-2 is “a directly light-switched cation-selective ion channel.” It “opens rapidly after absorption of a photon” to let positively charged ions through, and it settles to a smaller steady current under continuous light. The Committee's popular account adds two details. In frog eggs the channel opened within 0.2 milliseconds of a light pulse, and human and hamster kidney cells given the gene also became light-sensitive. The paper's abstract ends: “we demonstrate that ChR2 may be used to depolarize small or large cells, simply by illumination.”

Two features set channelrhodopsin apart from the light-driven pumps already known from salt-loving microbes, such as bacteriorhodopsin, which Oesterhelt and Walther Stoeckenius described in 1971. The first is speed. The Committee's background explains that pumps move ions slowly against their gradients, while a channel lets ions flow rapidly down them, on the timescale of a nerve impulse. The second is simplicity. Channelrhodopsin is a single protein that is both the light sensor and the channel, so in mammalian nerve cells a single gene is all that has to be delivered.

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Light Switches On a Nerve Cell, 2005

Deisseroth's new laboratory at Stanford had been testing candidate proteins that might trigger electrical impulses in nerve cells. The Committee's popular account relates that when he heard about channelrhodopsin-2 he wrote to Nagel and asked for the DNA. The team delivered the gene into rat nerve cells grown in culture, carried by a modified virus (a lentivirus). The cells produced the protein with no apparent problems, and blue light made them fire.

The paper appeared in Nature Neuroscience in 2005, with Edward Boyden as first author and Feng Zhang, Ernst Bamberg, Georg Nagel and Karl Deisseroth as co-authors. It reported “reliable, millisecond-timescale control of neuronal spiking, as well as control of excitatory and inhibitory synaptic transmission.” Trains of light pulses produced matching trains of nerve impulses. The Committee's background highlights an observation it credits to Nagel: no retinal had to be added, because the trace amounts already present in the cells were enough.

Within about a year, the Committee notes, other studies extended the result to the chick spinal cord, the worm C. elegans, fruit-fly larvae and the retina.

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Into the Living Brain, 2006–2007

The method got its name in 2006. In a review in The Journal of Neuroscience, Deisseroth and five co-authors (Feng, Majewska, Miesenböck, Ting and Schnitzer) described the rapid progress of “interdisciplinary ‘optogenetic’ approaches” that combine optics and genetics. The Nobel Committee credits this review with formally coining the term optogenetics.

The next step was the intact, awake animal. In 2007, Deisseroth's group reported an “optical neural interface.” It used a laser diode coupled to a lightweight, flexible optical fibre about 200 micrometres in diameter, delivering blue light at 473 nanometres. The team put channelrhodopsin-2 only into excitatory nerve cells, using a genetic switch called the CaMKIIα promoter that is active in those cells. Light then drove the motor cortex of living rodents and controlled their behaviour: the Committee's background describes the light moving the animals' whiskers. “No exogenous chemical cofactor was needed at any point,” the paper noted, calling this “a crucial finding for in vivo work in large mammals.”

The same year brought one of the first causal tests of a behaviour. Working with Luis de Lecea's laboratory, Deisseroth's group put channelrhodopsin-2 into the hypocretin (orexin) neurons of the lateral hypothalamus. Loss of hypocretin function has been linked to narcolepsy. The team stimulated these neurons through an optical fibre in freely moving mice. Stimulation increased the probability of waking from both slow-wave sleep and REM sleep. Pulse trains at 5–30 Hz shortened the time to waking, while 1 Hz trains did not. The authors wrote that the study “establishes a causal relationship between frequency-dependent activity of a genetically defined neural cell type and a specific mammalian behaviour.”

An off switch followed in 2007. Feng Zhang and colleagues in Deisseroth's laboratory, with Nagel, Bamberg and Gottschalk, adapted halorhodopsin, a light-driven chloride pump from the salt-loving microbe Natronomonas pharaonis. Xue Han and Edward Boyden did the same independently, the Committee notes. Yellow light makes the pump drive chloride into the cell, which silences it. Halorhodopsin and channelrhodopsin-2 respond to well-separated colours, so the Zhang paper called the pair “a complete system for multimodal, high-speed, genetically targeted, all-optical interrogation of living neural circuits.” The background also traces later improvements: chloride-conducting channelrhodopsins engineered in 2014, and natural light-gated anion channels that Spudich's group found in another alga in 2015.

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How Optogenetics Works, in Plain Language

An optogenetic experiment has three parts.

1. A gene for a light-sensitive protein. The best known is channelrhodopsin-2 from the alga. The gene is delivered by a virus that has been modified to carry it. The 2005 neuron experiments used a lentivirus. The 2006 mouse-retina study and the 2021 and 2026 eye trials used adeno-associated viral (AAV) vectors.
2. A genetic address. Genetic targeting confines the protein to a chosen cell type, so only those cells become light-sensitive. The 2007 motor-cortex study did this with a promoter, a stretch of DNA that switched the gene on only in excitatory neurons. The 2007 sleep study targeted hypocretin neurons.
3. Light, delivered to those cells. In animal brains the light travels through a thin optical fibre. In the ChrimsonR eye trials, goggles detect changes in the surrounding light and project matching light pulses onto the retina.

When blue light reaches channelrhodopsin-2, its pore opens and positively charged ions flow into the cell. This shifts the voltage across the membrane (depolarization) and, if the shift is large enough, sets off a nerve impulse. That is the same electrical signal whose ionic basis Hodgkin and Huxley worked out. The site's animation How a Nerve Signal Travels shows it step by step. Halorhodopsin works the other way. Yellow light makes it pump chloride ions in, which moves the voltage further from the firing threshold (hyperpolarization) and silences the cell. Both proteins act on the millisecond timescale of nerve signals, so a pattern of light pulses can be turned into a matching pattern of impulses.

Channelrhodopsin captures light with retinal, the vitamin A–derived molecule that the eye's own rhodopsin also uses (see Wald, Hartline & Granit and Vitamin A and Vision). Nagel's frog-egg experiments supplied the all-trans form. In mammalian nerve cells, the 2005 and 2007 studies found that the trace already present was enough.

Optogenetics can also target a single connection. The protein reaches the endings of a neuron's fibres, so light aimed at those endings in a distant brain area activates just that pathway. The 2011 anxiety experiments below used this.

A complementary method, chemogenetics, developed largely in Bryan Roth's laboratory from 2007, gives cells an engineered receptor that ignores the body's own neurotransmitters but responds to an otherwise inert synthetic drug. The Committee's background calls it slower and suited to prolonged changes in activity. In its words, optogenetics “uniquely solved the problem of interrogating fast neural dynamics.”

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What It Revealed About the Brain and Body

The method's largest effect has been on knowledge. The Committee's background describes neuroscience moving from observing and “reading” brain activity to actively “writing” into it. A few examples follow, all from experiments in rodents.

• Memory. In 2012, Susumu Tonegawa's laboratory, with Deisseroth as a co-author, put channelrhodopsin-2 into the hippocampal neurons that were active while mice learned to fear a particular place. When those neurons were later reactivated with light in a different place, the mice froze, a sign of fear-memory recall. The authors concluded that activating “a sparse but specific ensemble of hippocampal neurons that contribute to a memory engram is sufficient for the recall of that memory.” The site's page on Susumu Tonegawa describes this work.
• Anxiety. In 2011, Deisseroth's group studied the connection from the basolateral to the central amygdala in mice. Stimulating it “exerted an acute, reversible anxiolytic effect,” and silencing the same connection increased anxiety-related behaviour. Controlling the cell bodies in the basolateral amygdala directly did not produce these effects. (See Anxiety.)
• Parkinson's disease and deep brain stimulation. Deep brain stimulation is a treatment option for neurological and psychiatric disorders that resist other treatment, including Parkinson's disease, but which cells it acts on was unclear. In 2009, Deisseroth's group switched distinct circuit elements on and off in parkinsonian rodents. They found that the therapeutic effects in the subthalamic nucleus “can be accounted for by direct selective stimulation of afferent axons projecting to this region,” meaning incoming fibres rather than the local cells.
• Heart and brain. In 2023, Deisseroth's group built a non-invasive optogenetic pacemaker for mice. They found that optically raising the heart rate “potently enhanced anxiety-like behaviour, but crucially only in risky contexts.” Silencing one brain region, the posterior insular cortex, reduced the effect.

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In the Clinic: Partial Vision, and Hearing Research

The press release says that in clinical medicine, researchers are using the method “in attempts to restore sight in people with visual impairment.” In retinitis pigmentosa, an inherited disease, the light-sensing rods and cones die. A 2022 review notes that other retinal neurons, the bipolar cells and ganglion cells, “remain largely structurally intact, even in end-stage disease.” Making those cells light-sensitive could work whatever gene caused the disease, the review notes, and so reach more patients than a therapy aimed at one specific gene.

• 2006, mice. Zhuo-Hua Pan's group used an AAV vector to put channelrhodopsin-2 into surviving inner retinal neurons of mice with photoreceptor degeneration. This restored the retina's ability “to encode light signals and transmit the light signals to the visual cortex.”
• 2021, one patient. In Nature Medicine, Sahel, Roska and colleagues reported on a blind patient with retinitis pigmentosa. The patient received an injection into the eye of an AAV vector carrying ChrimsonR, a red-shifted channelrhodopsin (one that responds to longer-wavelength light), and wore goggles that project light pulses onto the retina. Wearing the goggles and using the treated eye alone, the patient perceived, located, counted and touched objects. Before the injection, and after it without the goggles, the patient could not visually detect any objects. The authors called it “the first reported case of partial functional recovery in a neurodegenerative disease after optogenetic therapy.”
• 2026, ten participants. On 8 October 2026, The New England Journal of Medicine published the open-label PIONEER study (ClinicalTrials.gov NCT03326336). It tested the same ChrimsonR-and-goggles approach in 10 people with blindness from advanced retinitis pigmentosa, each given a single injection into the worse-seeing eye. Its primary outcome was safety. There were 34 eye-related adverse events among 9 of the 10 participants: 23 mild, 10 moderate and one severe. The severe event was a transient blockage of the central retinal artery immediately after the injection, which resolved within minutes after medicated eye drops were given. Light sensitivity rose in 7 of the 10, by factors ranging from 2.0 to 62.3. Six met a threshold for clinically meaningful improvement that the authors took from the literature and that was not prespecified in the protocol. The authors concluded that “within the limits of this small study” the treatment was safe, and that “additional research is needed to further assess safety and efficacy.”
• 2026, a negative result. A first-in-human, open-label, dose-escalation phase I/IIa trial tested a different therapy, which delivers channelrhodopsin-2 by injection into the eye, in 14 patients with advanced retinitis pigmentosa. Its report in Ophthalmology Science states that “no clinically significant efficacy was observed.” The authors also reported no safety concerns over five years after the injection.
• 2025, a different target cell. A six-person, open-label phase 2 study in Stargardt disease tested an optogenetic gene therapy aimed at bipolar cells rather than ganglion cells. All six had at least one eye-related adverse event, most often bleeding under the conjunctiva, raised eye pressure or cells in the vitreous gel. None had a retinal detachment or endophthalmitis. Best-corrected visual acuity changed from baseline by 5.5 ± 12.29 letters at 48 weeks, and the authors concluded that the results “support further investigation.”

No optogenetic therapy appears on the U.S. Food and Drug Administration's list of approved cellular and gene therapy products, which the agency marks as current as of 17 September 2026. The Committee's background states that “several clinical trials using optogenetic approaches to improve vision in patients with retinitis pigmentosa are presently underway.”

Hearing is also under study. Cochlear implants stimulate the auditory nerve electrically, but “electric current is hard to focus in conductive environments such as the cochlea,” a 2020 review explains, while light can be confined more tightly. In 2018, Moser's group injected the cochlea of adult gerbils with an AAV vector carrying a channelrhodopsin gene. In deaf animals, light then “generated auditory responses and cued avoidance behavior indicating partial restoration of auditory function.” The review, from the same group, sets out “the remaining challenges on the way to clinical translation.” (See Hearing Loss and Georg von Békésy.)

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Limits and Open Questions

• It is gene therapy. A 2022 ethics review notes “great hype” around optogenetics as a treatment for retinitis pigmentosa. It points out that the treatment “involves irreversible gene therapy and requires access to specially designed goggles to deliver light to the treated eye.” It argues that the first trials raise “numerous ethical issues” about treating participants fairly and obtaining appropriate informed consent.
• The human evidence is small and mixed. One trial of 10 people reported gains in light sensitivity for most participants, alongside 34 eye-related adverse events. Another, of 14 people, found no clinically significant efficacy. A third, of six people with a different disease, reported changes in visual acuity that varied widely between participants. All three were open-label studies in which every participant received the treatment.
• Light delivery and heat. In the animal studies on this page, light reached deep brain structures through optical fibres placed in the brain. Illumination also heats tissue. A 2019 study found that commonly used protocols raised brain temperature by 0.2–2 °C and suppressed nerve firing in several brain regions. In the striatum, light delivery activated a potassium current and biased the animals' turning behaviour. The authors concluded that “careful consideration of light-delivery parameters is required, as even modest intracranial heating can confound interpretation of optogenetic experiments.”
• Animal circuits are not human treatments. The memory, anxiety and heart experiments on this page were carried out in mice, and the Parkinson's experiments in rodents. A circuit that controls anxiety-like behaviour in a mouse reveals a mechanism. It does not establish a therapy for people.
• Design choices are still open. The 2022 retinal review identifies the factors that shape what vision can be restored: the light-sensitive protein used, the vector and method of gene delivery, and the target cell. The trials above differ on exactly these points: ChrimsonR or channelrhodopsin-2, ganglion cells or bipolar cells.

The science honoured by the prize is established. Channelrhodopsins are light-gated ion channels (2002–2003). In nerve cells they give millisecond control of nerve impulses (2005), and the method works in living animals (2007 onward). The clinical part is early. Small trials in blindness have reported partial gains in some participants, and one trial found no clinically significant efficacy. No optogenetic product appears on the FDA's list of approved gene therapies.

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Key Research Papers

1. Foster KW, Saranak J, Patel N, et al. A rhodopsin is the functional photoreceptor for phototaxis in the unicellular eukaryote Chlamydomonas. Nature 1984;311(5988):756-9. — PubMed PMID: 6493336
2. Harz H, Hegemann P. Rhodopsin-regulated calcium currents in Chlamydomonas. Nature 1991;351(6326):489-91. Not indexed in PubMed; record checked at Crossref. — DOI: 10.1038/351489a0
3. Harz H, Nonnengasser C, Hegemann P. The photoreceptor current of the green alga Chlamydomonas. Philos Trans R Soc Lond B Biol Sci 1992;338(1283):39-52. Not indexed in PubMed; record checked at Crossref. — DOI: 10.1098/rstb.1992.0127
4. Crick F. The impact of molecular biology on neuroscience. Philos Trans R Soc Lond B Biol Sci 1999;354(1392):2021-5. — PubMed PMID: 10670022
5. Zemelman BV, Lee GA, Ng M, Miesenböck G. Selective photostimulation of genetically chARGed neurons. Neuron 2002;33(1):15-22. — PubMed PMID: 11779476
6. Sineshchekov OA, Jung KH, Spudich JL. Two rhodopsins mediate phototaxis to low- and high-intensity light in Chlamydomonas reinhardtii. Proc Natl Acad Sci U S A 2002;99(13):8689-94. — PubMed PMID: 12060707
7. Nagel G, Ollig D, Fuhrmann M, et al. Channelrhodopsin-1: a light-gated proton channel in green algae. Science 2002;296(5577):2395-8. — PubMed PMID: 12089443
8. Nagel G, Szellas T, Huhn W, et al. Channelrhodopsin-2, a directly light-gated cation-selective membrane channel. Proc Natl Acad Sci U S A 2003;100(24):13940-5. — PubMed PMID: 14615590
9. Boyden ES, Zhang F, Bamberg E, Nagel G, Deisseroth K. Millisecond-timescale, genetically targeted optical control of neural activity. Nat Neurosci 2005;8(9):1263-8. — PubMed PMID: 16116447
10. Deisseroth K, Feng G, Majewska AK, Miesenböck G, Ting A, Schnitzer MJ. Next-generation optical technologies for illuminating genetically targeted brain circuits. J Neurosci 2006;26(41):10380-6. — PubMed PMID: 17035522
11. Bi A, Cui J, Ma YP, et al. Ectopic expression of a microbial-type rhodopsin restores visual responses in mice with photoreceptor degeneration. Neuron 2006;50(1):23-33. — PubMed PMID: 16600853
12. Aravanis AM, Wang LP, Zhang F, et al. An optical neural interface: in vivo control of rodent motor cortex with integrated fiberoptic and optogenetic technology. J Neural Eng 2007;4(3):S143-56. — PubMed PMID: 17873414
13. Zhang F, Wang LP, Brauner M, et al. Multimodal fast optical interrogation of neural circuitry. Nature 2007;446(7136):633-9. — PubMed PMID: 17410168
14. Adamantidis AR, Zhang F, Aravanis AM, Deisseroth K, de Lecea L. Neural substrates of awakening probed with optogenetic control of hypocretin neurons. Nature 2007;450(7168):420-4. — PubMed PMID: 17943086
15. Gradinaru V, Mogri M, Thompson KR, Henderson JM, Deisseroth K. Optical deconstruction of parkinsonian neural circuitry. Science 2009;324(5925):354-9. — PubMed PMID: 19299587
16. Tye KM, Prakash R, Kim SY, et al. Amygdala circuitry mediating reversible and bidirectional control of anxiety. Nature 2011;471(7338):358-62. — PubMed PMID: 21389985
17. Liu X, Ramirez S, Pang PT, et al. Optogenetic stimulation of a hippocampal engram activates fear memory recall. Nature 2012;484(7394):381-5. — PubMed PMID: 22441246
18. Wrobel C, Dieter A, Huet A, et al. Optogenetic stimulation of cochlear neurons activates the auditory pathway and restores auditory-driven behavior in deaf adult gerbils. Sci Transl Med 2018;10(449):eaao0540. — PubMed PMID: 29997248
19. Owen SF, Liu MH, Kreitzer AC. Thermal constraints on in vivo optogenetic manipulations. Nat Neurosci 2019;22(7):1061-1065. — PubMed PMID: 31209378
20. Dieter A, Keppeler D, Moser T. Towards the optical cochlear implant: optogenetic approaches for hearing restoration. EMBO Mol Med 2020;12(4):e11618. — PubMed PMID: 32227585
21. Sahel JA, Boulanger-Scemama E, Pagot C, et al. Partial recovery of visual function in a blind patient after optogenetic therapy. Nat Med 2021;27(7):1223-1229. — PubMed PMID: 34031601
22. Harris AR, Gilbert F. Restoring vision using optogenetics without being blind to the risks. Graefes Arch Clin Exp Ophthalmol 2022;260(1):41-45. — PubMed PMID: 34724112
23. De Silva SR, Moore AT. Optogenetic approaches to therapy for inherited retinal degenerations. J Physiol 2022;600(21):4623-4632. — PubMed PMID: 35908243
24. Hsueh B, Chen R, Jo Y, et al. Cardiogenic control of affective behavioural state. Nature 2023;615(7951):292-299. — PubMed PMID: 36859543
25. Lam BL, Zak V, Gonzalez VH, et al. Safety and efficacy of MCO-010 optogenetic therapy in patients with Stargardt disease in USA (STARLIGHT): an open-label multi-center Ph2 trial. EClinicalMedicine 2025;87:103430. — PubMed PMID: 40838197
26. Bunnell B, López FJ, Yuan D, Robinson MR, Duncan JL, Birch DG. Phase I/IIa Study of an Intravitreal Optogenetic Therapy (AGN-151597) in Patients with Advanced Retinitis Pigmentosa. Ophthalmol Sci 2026;6(9):101323. — PubMed PMID: 42602510
27. Sahel JA, Futterknecht S, Audo I, et al. Optogenetic Therapy for Restoring Aspects of Visual Function. N Engl J Med 2026;395(14):1399-1408. — PubMed PMID: 42842903

PubMed Topic Searches

1. PubMed: Channelrhodopsin and optogenetics
2. PubMed: Chlamydomonas phototaxis and rhodopsin
3. PubMed: Optogenetic therapy for retinitis pigmentosa
4. PubMed: Optogenetic cochlear implants

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Connections

• All Notable Doctors
• Nobel Prize in Physiology or Medicine — every prize year since 1901
• Neuroscience and the Senses — laureates whose prizes concern nerves and the senses
• Hodgkin, Huxley & Eccles — the nerve impulse that channelrhodopsin triggers
• Neher & Sakmann — the patch clamp, which gave access to single ion channels
• Wald, Hartline & Granit — vitamin A, retinal and the chemistry of seeing
• Cajal & Golgi — the neuron doctrine
• Susumu Tonegawa — the memory-engram experiments made with optogenetics
• Retinitis Pigmentosa — the disease in which optogenetic therapy is being tested
• Stargardt Disease — the subject of a bipolar-cell optogenetic trial
• Narcolepsy — linked to loss of hypocretin function
• Parkinson's Disease — how deep brain stimulation acts, studied in rodents
• Hearing Loss — optical cochlear implants, in animal studies
• How a Nerve Signal Travels — animation of the impulse that light switches on
• How You See (Inside the Eye) — animation of how rods and cones turn light into a signal

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