Like the steady synchronized blink of a string of holiday lights, certain types of nerve cells in the cerebral cortex communicate with each other through electrical connections, forming a new type of brain circuitry described in the current Nature.

Until now, scientists thought nerve cells in the cerebral cortex, the sinuous bumps on top of the brain, communicated only through chemical signals.

The cerebral cortex contains two types of nerve cells excitatory or inhibitory. Each neuron a nerve cell in the brain communicates with other neurons through chemical connections that fire off a tiny bit of chemical that either inhibits or excites the next neuron. These connections between neurons are called synapses.

While studying the chemical synaptic connections in the cerebral cortex of rats, Brown University researchers found that two separate types of inhibitory neurons were also using electrical synaptic connections to communicate, but only within their specific groups.

The cerebral cortex is the biggest part of the brain. This large and complicated neural circuit is involved in most of the brain's highest functions, such as memory, language and sight. Within each type of excitatory or inhibitory cell, circuitry keeps neurons interconnected and communicating to keep overall brain activity in balance. Too much excitation and too little inhibition, for example, may lead to seizures. The opposite may lead to a loss of consciousness, coma or death.

The presence of electrical synapses in the cerebral cortex allows each network of inhibitory neurons to fire in a highly coordinated and direct way, as if there were a wire directly connecting the cells, said Barry Connors, professor of neuroscience and senior author of the study. "We think the inhibitory cells are coordinating their activity through the electrical synapses," he said. The result is synchrony
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Contact: Scott Turner
Scott_Turner@Brown.edu
401-863-1862
Brown University
3-Nov-1999