2026 Nobel Prize in Physiology or Medicine: Optogenetics and Neural Control

Subject: GS Paper 3: Science and Technology

Context: The 2026 Nobel Prize in Physiology or Medicine was awarded to Karl Deisseroth, Peter Hegemann, and Georg Nagel for discoveries that led to Optogenetics.

• The laureates will share the prize, worth 12 million Swedish kronor (₹11.5 crore), equally.

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Key Discoveries

• Peter Hegemann: Investigated how the single-celled alga Chlamydomonas swims towards light and, along with Georg Nagel, discovered channelrhodopsin, a light-sensitive protein located on the cell surface.
• Georg Nagel: Collaborated with Hegemann to establish that channelrhodopsins act as light-sensitive ion channels. 
  • In particular, channelrhodopsin-2 (ChR2) opens when exposed to light, allowing positively charged ions to enter the cell and generate an electrical signal. It opens within about 0.2 milliseconds of light exposure.
• Hegemann and Nagel: Demonstrated that introducing the gene for channelrhodopsin into mammalian cells could make them sensitive to light.
• Karl Deisseroth: Recognised that channelrhodopsin could be used as a light-controlled switch for specific neurons by combining genetic methods with light.
  • Targeted Neuronal Control: Enabled light-sensitive proteins to be targeted to specific neuronal populations, allowing their activity to be controlled with light.
  • First Major Demonstration: His team introduced the channelrhodopsin gene into rat nerve cells and showed that blue light could trigger a nerve signal in 2005.
  • Application in Living Mice: In 2007, his group used a fiber-optic cable to stimulate specific neurons in the brains of living mice.

About Optogenetics

• Optogenetics: A neuroscience technique that combines genetic engineering and light to selectively control the activity of specific neurons.
• Role of Opsins: Uses light-sensitive proteins called opsins to make targeted neurons responsive to light.
• Why It Is Useful: Allows researchers to selectively control specific neurons and determine their role in behavior, emotions, and brain functions.
• Applications: 
  • Neuroscience: Helps study neural circuits involved in memory, pain, attention, sleep, social behavior, thirst, food consumption, and reward.
  • Disease Research: Helps understand how abnormal neural circuits contribute to Alzheimer’s disease, Parkinson’s disease, depression, and schizophrenia.
  • Therapeutic Potential: Being explored for vision restoration, including in retinitis pigmentosa, and for improving cochlear implant precision.

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How Does Optogenetics Work?

• Gene Introduction: A gene coding for a light-sensitive opsin is introduced into specific target neurons.
• Opsin Expression: The targeted neurons produce opsin proteins.
• Light Stimulation: Light of a specific wavelength is directed at the targeted neurons.
• Ion Movement: Light activates the opsins, causing ion channels to open or close and altering the flow across the cell membrane.
• Neuronal Control: This changes the electrical activity, allowing scientists to activate or inhibit it.
• Observation: Researchers observe the resulting changes in brain activity or behavior to determine the function of the targeted neurons or neural circuits.

News Source: The Hindu

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