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Visualizing cause and effect in the brain

Two of the biggest challenges facing neuroscientists involve visualizing the brain on the one hand, and influencing it on the other.  These two have a lot to tell us about the brain individually, but what would be truly powerful would be combining the two in one study.

This is just what a group of researchers at MIT are trying to accomplish, pioneering a new method called "opto-fMRI" that uses the visual information provided by fMRI with the ability to activate specific neural circuits by using optogenetics.

For those of you unfamiliar with these techniques, fMRI is essentially a way of visualizing neural activity by observing blood flow in the brain.  The idea is that, as particular areas of the brain function at a higher level of activity (eg, if they are used in some task that is being performed), then the body will send more blood to that area in order to keep them well-nourished and functioning correctly.  fMRI essentially monitors this blood flow over time, piecing together a map of neural activation that can show connections and circuits between brain regions.

Visualizing the brain is all well and good, but it doesn't allow us to actually influence particular neurons or circuits.   This is where optogenetics is particularly useful.  It involves breeding mice (or worms, rats, etc) that express particular kinds of proteins that are sensitive to certain wavelengths of light (called channelrhodopsin).  These proteins exist in the nervous system, and when their "target" color of light is shown, they cause the neurons they're associated with to fire.  This allows for a very fast-paced control over the nervous systems of these animals, achieving a level of precision we do not usually have.

You can probably see where scientists are going with the combination of these two techniques.  By having one technology that lets us visualize the entire brain, and another that allows us to influence a very specific location in the brain, we can start to investigate how that specific region might connect with other areas that span long distances (relative to the brain, at least).

This is a pretty new technology, so we'll have to wait and see what researchers come up with by using these techniques, but the potential applications for such a technology are quite exciting.  By being able to see the distal connections between many locations in the brain, we'll gain a better understanding of the interconnected web of neural activity associated with all kinds of behaviors.

via MIT News

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