Windows on the brain

By monitoring the activity of up to a hundred brain cells at once, neuroscientists are gaining new insights into brain function and paving the way for fully functioning prosthetic limbs.

Abstract

the early 1970s, when researchers mapping connections within the brain began comparing readings taken from pairs of neurons 1 .They noticed that, in some cases, the firing of one neuron preceded the silencing of another, and reasoned that the first neuron was sending signals that, either directly or indirectly, inhibited the second cell.The technique has since been used to map the connections between many different brain areas.But more ambitious multi-unit studies were slow to take off."It is more difficult to record from two or more neurons than it is from one," explains Charles Gray of Montana State University in Bozeman."Ifyou can get a lot of information from one neuron, A robotic arm flexes as it receives commands from a monkey's neurons.Scientists probe an animal's perceptions and intentions.The dreaming brain comes into view as a rat's memory-traces are shown being replayed during sleep.Thanks to tools developed to monitor the activity of up to 100 individual neurons simultaneously, these futuristic scenarios are now an everyday reality in some of the world's top neuroscience labs.Such 'multiunit' recording is poised to transform brain research."It will mark the transition of neurophysiology from small science to big science," predicts Vernon Mountcastle of Johns Hopkins University in Baltimore, Maryland, whose recordings from single nerve cells helped to underpin present textbook principles of brain function.For decades, neuroscientists have implanted electrodes into the brain to listen in as neurons talk to one other.When one brain cell sends a signal to another,it fires off a voltage pulse along a fibre leading towards the next neuron.This pulse can be detected by electrodes placed close to the firing neuron.