REHOVOT, Israel -- January 12, 2000 -- Despite more than a century of research on inhibitory neurons, very little is known on how this small population (10-20% of brain neurons) exerts its controlling effect on the brain. Pivotal for normal brain development, learning, and memory, it is not surprising that inhibitory neurons are involved in most neurological disorders. A recent study at the Weizmann Institute of Science, published in the January 2000 issue of Science, reveals key principles underlying the design and function of this inhibitory system.
By repressing the level of activity in neighboring neurons, inhibitory neurons (I-neurons) prevent the brain from quickly spinning out of control into hyper-excited states or full-blown epilepsy. One of the problems that children with autism and attention deficit hyperactivity disorders (ADHD) have is I-neuron malfunction: their inhibitory system does not effectively suppress unwanted information, impeding their ability to make choices. I-neuron malfunction is involved in memory disorders (such as Alzheimer's disease), neural trauma, and addictions. It also plays a role in a wide range of psychiatric disorders, such as depression, obsessive compulsive disorders, and schizophrenia.
In the past, researchers basically thought that I-neurons just sprayed an inhibitory neurotransmitter called GABA onto their neighbors. But this did not explain how they inhibited the right neurons at exactly the right time and to the right degree. The new study carried out in the laboratory of Prof. Henry Markram of the Weizmann Institute's Neurobiology Department shows how they achieve this.
Controlling the neuron crowd
The research team found new types of I-neurons, revealing that this tiny population is several times more diverse than previously thought. Further, using new methods that they developed, the researchers succeeded in recording directly how individual inhibitory neurons control their neighbors. T
Contact: Jeffrey J. Sussman, Asst. V.P. Communications
American Committee for the Weizmann Institute of Science