CSHL scientists make progress in determining how the brain selectively interp...( Cold Spring Harbor NY Scientists at...),Health

Cold Spring Harbor, NY Scientists at Cold Spring Harbor Laboratory (CSHL) have reported new findings about how the mammalian brain interprets and fashions representations of sound that may help explain how we are able to focus on one particular sound among many in noisy environments such as offices or cocktail parties.

Neurons in the brains auditory cortex interpret incoming sound signals and send them to the rest of the nervous system, in the brain and spinal cord. Using rats, the CSHL team discovered that a very small minority of available auditory neurons react strongly when exposed to any specific sound.

This finding challenges the standard model of sound representations in the auditory cortex, which predicts that neural representations of stimuli often engage a large fraction of neurons, said Anthony Zador, Ph.D., CSHL professor and corresponding author of a research paper published today in the journal Public Library of Science: Biology.

The researchers used a new technique called in vivo cell-attached patch clamp recording which measures the reaction of individual neurons. This recording technique samples neurons in a fair and unbiased way, unlike traditional approaches, which favored the largest and most active neurons. Using this technique, the team found that only 5% of neurons in the auditory cortex had a high firing rate when receiving a range of sounds of varying length, frequency, and volume. The experiment included white noise and natural animal sounds.

The teams objective was to quantify the relative contributions of different sub-populations of neurons in response to the range of sounds. Most of what is known about the auditory cortex of the mammalian brain comes from studies of the anesthetized cortex. The results of the experiments reported today are important partly because they measure the response of neurons in rats that were not anesthetized. In animals that are awake, its possible to measure the re
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