Monday, March 18, 2013

Brain Activity Illuminated In A Zebrafish

The scientists studied live zebrafish larvae that had been genetically encoded with a calcium indicator called GCaMP5G. They suspended the larva in a gel and then beamed it with lasers. Just before a neuron fires, its action potential is expressed via a spike in calcium ions, so when one of the genetically modified larva’s neurons reached its action potential, it glowed. This showed the researchers the firing of the neurons without them having to attach a bunch of electrodes to the fish.

Over the course of an hour the researchers used laser beams to scan the larva every 1.3 seconds, exciting the retina of the zebrafish with each scan. This microscopy method allowed the researchers to record up to 80 percent of the fish’s 100,000 neurons at single-cell resolution.  This is the first time scientists have recorded such a high percentage of an organism’s brain activity at such a high resolution.




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