Monday, April 15, 2013

More than clear minded - a see-through brain

Karl Deisseroth, neuroscientist at Stanford University and his colleagues reported that they had developed a way to replace the opaque tissue in brains (harvested from lab mice or donated by people for research) with “hydrogel,” a substance similar to that used for contact lenses.

The result is see-through brains, their innards revealed in a way no current technique can: large structures such as the hippocampus show up with the clarity of organs in a transparent fish, and even neural circuits and individual cells are visible. This may make it possible to study intact brains, and give us a better chance of examining connections over large distances, which would help determine structure-function relationships.

The Stanford scientists are able to visualize the thalamus and the brainstem, the cortex and hippocampus with the naked eye. Using a microscope revealed the white matter that serves as a brain’s transmission lines, carrying signals from one neuron to another in far-flung circuits that underlie mental function.

It turns out that hydrogel is not only transparent but also permeable thus allowing scientists to infuse fluorescent dyes into the brain and other molecules that attach to specific brain cells, and even to individual proteins and other molecules, turning the circuitry a neuroscientist wants to study into can’t-miss hues when viewed in special light.  Deisseroth says “we could see structures down to paired neurons on each side of a synapse.”

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