Scientists have found a strong evidence for a novel type of communication between nerve cells in the brain.
The findings, published in Proceedings of the National Academy of Sciences, may have significance for the prevention and treatment of epilepsy, and perhaps in the exploration of other aspects of brain functions, from creative thought processes to mental illnesses such as schizophrenia.
The study was performed jointly by scientists at SUNY Downstate Medical Center in Brooklyn, New York; Colorado State University in Fort Collins, Colorado; Mount Sinai School of Medicine in Manhattan, New York; and the University of Newcastle in the United Kingdom.
Epilepsy, a group of disorders characterized by the recurrent occurrence of spontaneous seizures, is usually regarded to reflect a disparity between the ability of nerve cells to excite one another, on the one hand, and to inhibit one another, on the other hand.
The excitation and inhibition take place because the activity of nerve cells leads to the release of particular chemicals, called neurotransmitters, which act as a "classic" means of communication between nerve cells, and lies at the base of most of current understanding of how the brain processes information and controls muscles in the body.
There is, however, another means for nerve cells to communicate with one another, called gap junctions. Gap junctions allow electric current to flow directly from one cell to another, without involving the release and diffusion of transmitter chemicals, and may be thought of as "short circuits" linking or cutting across the pathways through which cells normally communicate.
Gap junctions are found in many parts of the body, such as the heart and have been most studied in older vertebrates (such as fish) and in invertebrates (such as leeches and crabs).
The current study provides the first electron microscopic evidence for gap junctions on the axons of excitatory nerve cells in the mammalian brain. Gap junctions at this site, on axons, would be expected to act as short circuits for nerve signals and to produce "cross-talk."
However the new data raise the provocative question as to whether cross-talk is an aspect of normal brain function. But authors maintain that more needs to be learned about the distribution of gap junctions - what nerve cells have them, where on the cells are they located, and how are they controlled.
Also, more needs to be learned about exactly how gap junctions contribute to the very fast brain waves that can presage a seizure. And finally, it needs to be determined if attenuating or preventing these very fast brain waves can prevent seizures.
However, authors say that that these findings give a whole new direction to understanding the origins of epilepsy, and conceiving new approaches to treatment and prevention.