Scientists have gained a deeper understanding of social dysfunction in neurological disorders such as autism.

Newly discovered immune vessels in the brain appear to control social behaviour, a finding that could have future implications for neurological disorders such as autism, say US scientists.

The never-before-seen vessels, announced last year, were found in the meninges - the layer of tissue that covers the brain.

The discovery debunked the belief that the immune system is external to the brain.

Further research by scientists at University of Virginia, published in the latest Nature journal, has found these immune vessels controlled social behaviour in mice.

"Peripheral immune cells, peripheral to the brain, are having an effect on how the brain is working," Professor Jonathan Kipnis explained in a university video.

By interfering with immune molecule interferon gamma, the scientists were able to manipulate the social behaviour of the mice.

Interferon gamma is normally produced by the immune system in response to bacteria or viruses.

When they switched off this molecule using genetic modifications, the mice stopped interacting with each other, and when they activated it again social behaviour was restored.

"When we remove this one molecule, that we discovered to be involved in social interaction, the brain regions become hyper-connected," Professor Kipnis said.

"It's like little airports in small cities now become major hubs and so there's mess in the air, same thing happens with the brain which can not function properly, so when we provide this molecule back, the brain can function normally."

A malfunctioning immune system may be responsible for social deficits in neurological disorders, the authors said.

But just what this might mean for autism requires further investigation and is unlikely to lead to a cure, they noted.

Those on the autism spectrum struggle daily with social interactions and picking up on social cues.

Previous studies have found people with autism show signs of immune problems and this association has become the focus of many neuroscientists in recent years.

Neuroscientist Elisa Hill from University of Melbourne, who is studying the genetics underlying the relationship between autism and changes in the gut, described this new research as really exciting.

"Social behaviour is really complex and there are going to be many, many factors contributing but their study shows a mechanism by which the immune system might be influencing specific cells in regions of the brain that are related to social behaviour," she said.