Boosting levels of a protein in the brain could be a way of treating diseases such as epilepsy and schizophrenia, scientists suggest.
In seizures, electrical surges cause message scrambling in the brain
Researchers at the University of Bristol say the SUMO protein acts to damp down the amount of information transmitted to cells.
Such "over-excitement" is characteristic of many conditions which affect the brain.
Experts said the findings in Nature would further understanding.
There are 100 million nerve cells in the brain, which each have 10,000 connections, called synapses, which link to other nerves cells.
These connections chemically transmit information that control brain function via proteins called receptors. These processes are believed to be the basis of learning and memory.
In a healthy brain, synapses can modify how efficiently they work, by increasing or decreasing the amount of information transmitted.
Having too much information is a problem, but so is having too little which can cause conditions including coma.
The researchers, who carried out work on rats, found that when one type of receptor, the kainate receptor, receives a chemical signal a small protein called SUMO attaches itself.
SUMO pulls the kainate receptor out of the synapse, stopping it from receiving information from other cells and making the cell less excitable.
The scientists who discovered SUMO's role say it is interesting because it means the receptor is not destroyed, but simply lies dormant, meaning the dangers of completely cutting off communication between cells should be avoided.
Professor Jeremy Henley, who led the research, said: "We have found one mechanism that regulates the flow of information between cells in the brain.
"It is important because it gives a new perspective and a deeper understanding of how that happens.
"It is possible that increasing the amount of SUMO attached to kainate receptors - which would reduce communication between the cells - could be a way to treat epilepsy by preventing over-excitation."
The researchers say that their findings could also provide insight into other brain diseases that are characterised by too much synaptic activity, like schizophrenia, which could one day lead to new drugs.
'Making a difference'
Professor Ley Sander, an epilepsy expert at the Institute of Neurology, said the work was at early stages but was interesting.
"This is an additional part of the puzzle and it is interesting to learn more about brain processes.
"But we are talking about five to 10 years if this is really going to make a big difference."
Jo Loughran, of the mental health charity Rethink, said: "We welcome this exciting new research and hope that one day it could make a difference to the thousands of people living with severe mental illnesses like schizophrenia.
"We would like to see continued investment in such research that will lead to a third generation of antipsychotic medicines with fewer side effects."