"Hegemann, Nagel, Deisseroth Share Medicine Nobel for Optogenetics"
Optogenetics
a technique using light to control the activity of genetically targeted cells, especially neurons
Channelrhodopsin
a light-gated ion channel protein first identified in green algae
The 2026 Nobel Prize in Physiology or Medicine recognises a technique that let scientists control specific nerve cells using light, transforming neuroscience from passive observation to active intervention. For most of the twentieth century, researchers could map which brain regions governed movement, emotion, and memory, but could not prove that one specific type of nerve cell directly caused a particular behaviour. The resulting picture of the brain was often described as a blurry photograph: broad regions were linked to functions, but the precise wiring remained unclear.
Francis Crick, who shared the 1962 Nobel Prize for discovering the structure of DNA, proposed a possible solution decades later. Because nerve signals travel extremely fast, he reasoned that light, which can be switched on and off in fractions of a second, would be an ideal tool to control neural activity if nerve cells could somehow be made to respond to it. Crick considered the idea far-fetched at the time, but it set the conceptual stage for a technique that his successors would eventually build using a protein borrowed from a single-celled alga.
The central actors in this discovery are light-gated ion channels, proteins embedded in a cell's membrane that work like tiny doors. When a specific wavelength of light strikes the protein, it changes shape and opens, letting charged particles called ions flow across the membrane and generate an electrical signal. This is how the human eye converts light into nerve impulses, but that process needs several intermediate proteins and is comparatively slow.
Peter Hegemann, studying the unicellular alga Chlamydomonas, noticed that it swam toward a light source within milliseconds using a light-sensing structure called an eyespot. He hypothesised that in this alga, a single protein both senses light and passes on the electrical signal, unlike the multi-step process in the human eye. …
Which of the following statements about transport across the plasma membrane is/are correct?
1.Facilitated diffusion requires carrier or channel proteins to move molecules along their concentration gradient.
2.Movement of molecules against their concentration gradient always occurs without expenditure of energy.
3.Light-gated ion channels are a specialised category of channel proteins that open in response to light rather than a concentration gradient alone.
Select the correct answer using the code given below:
Which of the following best describes 'optogenetics'?
With reference to the discoveries honoured by the 2026 Nobel Prize in Physiology or Medicine, consider the following pairs:
1.Peter Hegemann — Hypothesised that a single protein performs both light-sensing and ion-channel function in an alga
2.Georg Nagel — Confirmed channelrhodopsin proteins act as light-gated ion channels using frog egg cells
3.Karl Deisseroth — Introduced channelrhodopsin-2 into mammalian nerve cells to enable optogenetic control
How many of the above pairs are correctly matched?
Consider the following statements about channelrhodopsin-2:
1.It was originally discovered in the unicellular alga Chlamydomonas reinhardtii.
2.It opens in response to light and allows negatively charged ions to flow into the cell.
3.Its light response occurs within about 0.2 milliseconds of a light pulse.
Which of the statements given above is/are correct?
The idea that nerve cells could one day be controlled using light was first conceptually proposed by a Nobel laureate best known for an entirely different discovery. Who was this scientist?
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