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Spectrum: Autism Research News

Cognition and behavior: Drug enhances social learning

by  /  27 May 2011
THIS ARTICLE IS MORE THAN FIVE YEARS OLD

This article is more than five years old. Autism research — and science in general — is constantly evolving, so older articles may contain information or theories that have been reevaluated since their original publication date.

Nuclear family: Prairie voles, which mate for life and raise their offspring together, are good models for testing compounds that influence social ties.

A compound that activates a pathway related to learning and memory can enhance pair-bonding between prairie voles, according to a study published 7 April in Biological Psychiatry1. Enhancing social learning — an individual’s response to social cues — during development could help treat autism.

The chemical messenger glutamate regulates the neural mechanisms underlying learning and memory and has been linked to fragile X syndrome and autism. D-cycloserine, an approved antibiotic, activates the same pathway as glutamate and has been used to treat individuals with social anxiety and obsessive-compulsive disorder2.

D-cycloserine injected under the skin of prairie voles induces them to form pair-bonds when they otherwise would not, the new study found. Prairie voles are monogamous and typically bond for life after mating, preferring the company of their mate to that of an unfamiliar vole.

In the new study, researchers removed the ovaries from female prairie voles so that they wouldn’t mate and then allowed them to interact with a male vole for six hours. When introduced into a different cage, these females spend only marginally more time with the familiar male than with an unfamiliar one.

But when they are injected with 10 milligrams of D-cycloserine per kilogram of body weight, they spend more time with the familiar vole, as if the compound had induced pair-bonding in the absence of mating. Injecting with 20 milligrams of D-cycloserine does not have the same effect, however. Too much D-cycloserine could actually inactivate the pathway by out-competing the natural activator, the researchers suggest.

D-cycloserine also enhances pair-bonding when injected directly into the amygdala or the nucleus accumbens — brain regions responsible for social learning.

By contrast, meadow voles — which are not very social and do not form pair bonds — do not respond to D-cycloserine treatment.

Some studies have suggested that lack of attention to social information during a key phase in development could cause the deficits associated with autism. Drugs that reinforce social learning could be one way to compensate for this deficit, and prairie voles are good animal models to screen for these, the researchers suggest.

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