Their study, published online by Nature Neuroscience, depicts how specific types of inhibitory neurons in the visual cortex of a rat brain are wired to, and "talk" with, discrete excitatory neurons. They also show how that "conversation," aimed at keeping the right balance of chemical signals, often excludes surrounding neurons.

"The inhibitory neurons are not just brakes, they can also be used to steer." said co-author Ed Callaway, Ph.D., associate professor in Salk's Systems Neurobiology Laboratories. For example, in vision, inhibitory responses in the visual cortex help people to focus on what they want to see, rather than all there is to see, he explained.

This new study is filling in the picture of how the brain is organized into "smart" efficient networks, and researchers hope that details of this complex design might, one day, uncover the roots of such neurological diseases as schizophrenia.

"We know already that schizophrenia is a problem with organization of inhibitory circuits of neurons, and now we are uncovering how these specialized nerve cells work together and with other neurons," Callaway explained.

"By understanding the brain in finer and finer resolution, we can then trace what happens when these neural circuits are mis-wired," he added.

The Nature Neuroscience report is the latest published study in a series by Callaway and first author Yumiko Yoshimura, of both Salk and Japan's Nagoya University, that reveal how neurons in the brain's cortex are finely wired to pass on thought and perception.

The brain cortex is the folded tissue that looks like the outside of cauliflower, but which in humans has
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Contact: Cathy Yarbrough
yarbrough@salk.edu
858-453-4100 x1290
Salk Institute
21-Oct-2005