One of the two circuits, dubbed LTS neurons, may be involved in preventing runaway excitation among nerve cells in the cerebral cortex, Connors said. The electrical synapses may allow these neurons to generate activity over a large area of the brain, he said.
"It appears this one group is especially suited to regulating cortical function," he said. "Most of the time it is not doing anything. But it becomes active when the brain's activity increases to a high level. This network of inhibitory neurons may act like the governor on the engine of the cortex, keeping excitability from running away and becoming an epileptic seizure."
Some scientists have suggested that inhibitory neurons generate the brain's electrical rhythms. These rhythms offer clues to the brain's state. Rhythms are smaller and faster when one is awake and slower and larger during sleep. LTS neurons may be the rhythms' source.
"As we continue this research, we do suspect that this group of inhibitory cells may be the 'pacemaker' for generating some of the brain's rhythmic electrical activity, the kind measured by an EEG," Connors said.
The other electrical network of inhibitory neurons described in the study, called FS neurons, seems to be more directly involved in the processing of sensory information, he said.
Connors and colleagues study epilepsy, an illness often controlled by drugs that steady the brain's chemical signals to keep cellular networks in balance. Discovery of electrical interconnections among cells in the cerebral cortex may one day provide another pathway for the treatment of brain-based illnesses.
The study's lead author is Jay Gibson, postdoctoral fellow. The other author is graduate student Michael Beierlein. The National Institutes of Health funded the research.