`Social isolation disrupts white matter formation in brain`

Updated: Nov 12, 2012, 16:49 PM IST

Washington: People who are socially isolated for prolonged periods develop less white matter in the region of the brain responsible for complex emotional and cognitive behaviour, a new study has found.

The study found that the stress of social isolation disrupts the sequence in which the white matter or myelin-making cells, the oligodendrocytes, are formed.

Researchers led by the University at Buffalo found changes in the brain`s white matter or myelin have been seen before in psychiatric disorders, and demyelinating disorders have also had an association with depression.

Recently, myelin changes were also seen in very young animals or adolescents responding to environmental changes.

The research sheds new light on brain plasticity, the brain`s ability to adapt to environmental changes.

It reveals that neurons aren`t the only brain structures that undergo changes in response to an individual`s environment and experience, according to one of the paper`s lead authors, Karen Dietz.

"This research reveals for the first time a role for myelin in adult psychiatric disorders," Dietz says.

"It demonstrates that plasticity in the brain is not restricted to neurons, but actively occurs in glial cells, such as the oligodendrocytes, which produce myelin," he said.

Myelin is the crucial fatty material that wraps the axons of neurons and allows them to signal effectively.

White matter is the tissue through which messages pass between different areas of gray matter within the nervous system.

Normal nerve function is lost in demyelinating disorders, such as Multiple sclerosis (MS) and the rare, fatal, childhood disease, Krabbe`s disease.

In the experiment, adult mice, normally social animals, were isolated for eight weeks to induce a depressive-like state.

They were then introduced to a "novel" mouse, one they hadn`t seen before; while mice are normally highly motivated to be social, those who had been socially isolated did not show any interest in interacting with the new mouse, a model of social avoidance and withdrawal.

Brain tissue analysis of the socially isolated animals revealed significantly lower than normal levels of gene transcription for oligodendrocyte cells in the prefrontal cortex, a brain region responsible for emotional and cognitive behaviour.