"Our study shows that the inhibitory neurons are the master regulators that contact hundreds or thousands of cells and make sure that the inhibitory synapses at each of these contacts is matched to the different amounts of excitation that these cells are receiving," Scanziani explained. If, for example, the level of excitatory stimulation that a nerve cell is receiving is doubled, the inhibitory synapses over a period of a few days will also double their strength.
In terms of clinical applications, the scientists said that neurological diseases such as autism, epilepsy and schizophrenia are believed to be a problem, at least in part, of the brain's ability to maintain an optimal E/I ratio.
"If this E/I balance is broken, it completely alters your perception of the world," Scanziani said. "You will be less able to adjust and adapt appropriately to the range of stimulation in a normal day without being overwhelmed or completely oblivious, and E/I imbalances may be most easily noticed in social interactions because these interactions require such nuance and subtle adjusting."
Scientists have also proposed that some neurodegenerative diseases, such as Parkinson's and Huntington's disease, may be associated with a shift in the E/I balance.
Minghan Xue, a postdoctoral researcher in neurobiology and the study's lead author, said "now that we know how this E/I balance is regulated in a normal brain, we can begin to understand what goes wrong in the diseased state. It paves the way for interventions that might restore the balance in the brain."
|Contact: Scott LaFee|
University of California - San Diego