Posts Tagged ‘neurons

Control of traveling waves in the Mammalian cortex.

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January, 2005

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Control of traveling waves in the Mammalian cortex.

Richardson KA1, Schiff SJ, Gluckman BJ.
Author information
Krasnow Institute for Advanced Study
George Mason University
Fairfax, Virginia 22030, USA.


We experimentally confirmed predictions that modulation of the neuronal threshold with electrical fields can speed up, slow down, and even block traveling waves in neocortical slices. The predictions are based on a Wilson-Cowan-type integro-differential equation model of propagating neocortical activity. Wave propagation could be modified quickly and reversibly within targeted regions of the network. To the best of our knowledge, this is the first example of direct modulation of the threshold to control wave propagation in a neural system.

We therefore predicted that we could speed up, slow down, and block propagating neural activity in neocortical slices with the application of electric fields. Furthermore, we predicted that we could affect wave propagation either globally, over the whole slice, or locally, in a specific region of the slice, by changing the geometry of the applied field.

We experimentally confirmed theoretical predictions that threshold modulation can increase or decrease the propagation speed of, and even block, cortical traveling waves. To the best of our knowledge, this is the first example of direct modulation of threshold to control wave propagation in a neural system. Such modulation could be applied rapidly in a locally precise manner. Since neural systems permit direct access to threshold, these findings open avenues to novel neural prosthetic applications including control and containment of seizure propagation.


How to ‘take over’ a brain –

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How to ‘take over’ a brain –

By Leonard Mlodinow, Special to CNN
updated 11:14 AM EST, Mon January 7, 2013
The hottest field in science this past decade has been neuroscience. That explosion in research, and our understanding of the human brain, was largely fueled by a new technology called functional magnetic resonance imaging (fMRI) that became widely available in the 1990s. Well look out! Another technology-based neuroscience revolution is in the making, this one perhaps even bigger. The term to watch for in 2013 is “optogenetics.” It’s not a sexy term, but it is a very sexy technology.
The heritage of optogenetics goes way back to 1979, when Nobel Laureate Francis Crick, co-discoverer of the structure of DNA with James Watson and Rosalind Franklin, suggested that neuroscientists should seek to learn how to take control of specific cells in the brain.  …
Crick speculated that light could be the tool to use. That turned out to be true: Optogenetics involves inserting fiber-optics tools into an animal’s brain, in order to control the target neurons using pulses of light as a trigger. …
In order for the method to work, the neurons have to be re-engineered so that they react to the light. That was made possible by the amazing discovery of a kind of protein that can be used to turn neurons on and off in response to light.

The exotic light-sensitive protein is not present in normal neurons, so scientists designed a way to insert it. That is accomplished through a type of gene engineering called “transfection” that employs “vectors” such as viruses to infect the target neuron, and, once there, to insert genetic material that will cause the neuron to manufacture the light-sensitive protein.

Put it all together, and you have that sci-fi-sounding technology: genetically-engineered neurons that you can turn on and off at will, inside the brain of a living and freely-moving animal.

It is the combined use of optics and genetics that give optogenetics its name, but it’s not the “how” that makes optogenetics exciting, it is the “what.” Scientists didn’t really develop it to “take over” a creature’s brain. They developed it, like fMRI, to learn about the brain, and how the brain works, in this case by studying the effect of stimulating specific types of neurons.