Biomedical scientists at the University of California, Riverside, found a new mechanism responsible for the abnormal development of neuronal connections in the mouse brain, which can further lead to seizures and abnormal social behaviours, as per the study published in the Journal of Neuroscience.

The researcher examined the area of the brain called the hippocampus.

The hippocampus plays a vital part in learning and social interactions; and synapses, which are specialised contacts between neurons.

Each neuron in the brain receives numerous excitatory and inhibitory synaptic inputs. The balance between excitation and inhibition in neuronal circuits known as E/I balance — essential for circuit function, stability, and information processing in the central nervous system — can play a role in causing many neurological disorders, including epilepsy, autism spectrum disorder, and schizophrenia, the study noted.

The researchers stressed on a protein called ephrin-B1, which spans the membrane surrounding the cell and plays a role in maintaining the nervous system.

Iryna Ethell, a professor of biomedical sciences in the UCR School of Medicine, who led the mouse study, stated in an official statement: “We found the changes in the E/I balance are regulated by astrocytes in the developing brain through the ephrin protein.”

She added that astrocytic ephrin-B1 is linked to the development of inhibitory networks in the hippocampus during a critical developmental period, which is a new discovery.

“Specifically, we show the loss of astrocytic ephrin-B1 tilts the E/I balance in favour of excitation by reducing inhibition, which then hyperactivates the neuronal circuits. This hyperactivity manifests as reduced sociability in the mice and suggests they can serve as a new model to study autism spectrum disorder,” she added

The authors of the study believe that the findings can further the understanding of the mechanisms that lead to neurodevelopmental disorders.

“Hyperactivity of neuronal networks resulting from the loss or impaired function of inhibitory synapses can lead to neural dysfunctions and seizures,” Ethell added.

She concluded: “Like a car without brakes, the brain without inhibitory neurons cannot function properly and becomes overactive, resulting in loss of body control.”

Published on September 1, 2020