Optogenetics: The light switch for neurons
The 2026 Noble Prize for Physiology or Medicine was awarded to three scientists Karl Deisseroth, Peter Hegemann, and George Nagel for their work in the field of optogenetics. This begs the question what is optogenetics and its implications.
What is Optogenetics?
It is a technology developed by scientists, that used light to control the activity of neurons (brain cells) that are genetically defined. It is a widely used tool in neuroscience and is finding its way in clinical research.
Light as a tool for studying brain activity
According to Francis Crick, co-discoverer of the structure of DNA, deciphering the brain function would require perturbations of only a specific neuronal population leaving the rest intact. He further suggested that using light as a tool could be one of the ways this is possible. But he thought the idea was too far-fetched at the time.
Decades of research was done in the quest to determine how light could be used as a tool. The breakthrough came with the discovery of channelrodhopsin-1 and 2 microbial proteins that can function as a single unit as a photoreceptor and an ion channel (a channel that allows charged particles to cross the cell membrane).
How did scientist put these microbial proteins into neurons?
Deisseroth and his laboratory introduced the ChR2 gene into rat neurons grown in a petridish. The neurons were able to produce the protein. When they flashed blue light on these neurons they fired a signal to the neighboring neuron. This breakthrough study was published in 2005, demonstrating for the first time that a group of neurons can be fired together with precision using light.
Moving beyond the Petridish.
The next challenging step was to translate what they saw in a petridish to deeper brain structures in awake and behaving animals. After surmounting a lot of hurdles researchers were able to virally deliver Chr2 gene to the specific region of the brain in freely behaving mice. They were then able to use optical fibers to deliver light to this region of the brain to track a specific behavior. This herald in a powerful era in neuroscience. What started as a theoretical idea in Francis Cricks mind has been realized. Scientists were able to use light to control the firing of a specific set of genetically defined neurons in a live awake animal.
Implications
Optogenetics has revolutionized our understanding of the neuronal circuit dysfunction in conditions such as Parkinson’s, addiction, mood disorders and enhanced our understanding of neural circuits in normal behavior.
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