National Institute Of Health Study on Optogenetics – biological technique which involves the use of light to control cells can also control brain

Optogenetics is a biological technique which involves the use of light to control cells in living tissue, typically neurons, that have been genetically modified to express light-sensitive ion channels. It is a neuromodulation method employed in neuroscience that uses a combination of techniques from optics and genetics to control and monitor the activities of individual neurons in living tissue—even within

It is a neuromodulation method employed in neuroscience that uses a combination of techniques from optics and genetics to control and monitor the activities of individual neurons in living tissue—even within freely-moving animals—and to precisely measure these manipulation effects in real-time. The key reagents used in optogenetics are light-sensitive proteins. Neuronal control is achieved using optogenetic actuators like channelrhodopsin, halorhodopsin, and archaerhodopsin, while

Neuronal control is achieved using optogenetic actuators like channelrhodopsin, halorhodopsin, and archaerhodopsin, while optical recording of neuronal activities can be made with the help of optogenetic sensors for calcium (GCaMP), vesicular release (synapto-pHluorin), Neurotransmitter (GluSnFRs), or membrane voltage (Arc Lightning, ASAP1). Control or recording is confined to genetically defined neurons and performed in a spatiotemporal-specific manner by light.

The brain is an incredibly densely wired computational circuit, made out of an enormous number of interconnected cells called neurons, which compute using electrical signals. These neurons are heterogeneous, falling into many different classes that vary in their shapes, molecular compositions, wiring patterns, and the ways in which they change in disease states. It is difficult to analyze how these different classes of neurons work together in the intact brain to mediate the complex computations that support sensations, emotions, decisions, and movements—and how flaws in specific neuron classes result in brain disorders. Ideally, one would study the brain using a technology that would enable the control of the electrical activity of just one type of neuron, embedded within a neural circuit, in order to determine the role that that type of neuron plays in the computations and functions of the brain. Silencing a neuron would reveal what computations or pathologies it was necessary or critical for; activating a neuron would reveal which ones it was capable of driving or sustaining.

Ideally, one would study the brain using a technology that would enable the control of the electrical activity of just one type of neuron, embedded within a neural circuit, in order to determine the role that that type of neuron plays in the computations and functions of the brain. Silencing a neuron would reveal what computations or pathologies it was necessary or critical for; activating a neuron would reveal which ones it was capable of driving or sustaining.

Such a cell-targetable neural-control technology would open up a number of new frontiers in treating brain disorders. For example, by revealing the role that a given kind of neuron plays in a brain disorder state, or in overcoming a brain-disorder state, such technologies could reveal neurons in the brain that could serve as targets for more efficacious, reduced-side-effect drugs for treating brain disorders. Pinpointing the parts of a circuit that mediate a disorder could help neurosurgeons target electrodes to those areas for improved electrical neuromodulation. This could reveal better targets for disorders treated through deep brain electrical stimulation, such as Parkinson’s disease. And, if researchers could precisely enter information into specific cells in the brain, then such a technology might enable new kinds of prosthetics for the direct repair of complex brain disorders that are not treatable with any existing technologies.

This could reveal better targets for disorders treated through deep brain electrical stimulation, such as Parkinson’s disease. And, if researchers could precisely enter information into specific cells in the brain, then such a technology might enable new kinds of prosthetics for the direct repair of complex brain disorders that are not treatable with any existing technologies.

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Over the last decade a specific toolset, which has come to be known as optogenetics, has emerged—the set of microbial opsins, naturally occurring membrane proteins, that directly convert light into changes in electrical potential across the cell membranes into which they are inserted.

These molecules change the electrical potential of cells in which they are expressed in response to light, perhaps not unlike the way that a solar cell might be used to charge a battery. These reagents are genetically encoded and in many species do not require chemical supplementation for operation, which makes them easy to use. They also possess a very high speed of operation, responding to pulses of light with voltage changes that are precise to the millisecond. Microbial opsins respond to light by translocating ions across the membranes of the cells in which they are genetically expressed, making the neurons in which they are expressed sensitive to being activated or silenced by light.

These molecules change the electrical potential of cells in which they are expressed in response to light, perhaps not unlike the way that a solar cell might be used to charge a battery. These reagents are genetically encoded and in many species do not require chemical supplementation for operation, which makes them easy to use. They also possess a very high speed of operation, responding to pulses of light with voltage changes that are precise to the millisecond. Microbial opsins respond to light by translocating ions across the membranes of the cells in which they are genetically expressed, making the neurons in which they are expressed sensitive to being activated or silenced by light.

Credit : National Institute Of Health

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