A quarterly publication of the Autism Research Institute

The Autism Research Review International is quarterly publication of the Autism Research Institute

Summer, 2018 | Number 3, Volume 32

Differences seen in social reward pathway in ASD

A new study reveals that individuals with autism spectrum disorders (ASD) have structural and functional differences in a brain pathway that makes social behavior rewarding. 

In their study, Kaustubh Supekar and colleagues focused on the mesolimbic reward pathway, which connects two brain regions associated with reward—the ventral tegmental area (VTA) and the nucleus accumbens (NAc). The researchers note, “The mesolimbic reward pathway, which evaluates, regulates, and reinforces appetitive behaviors through dopaminergic signaling, is a core brain system for processing reward value.” 

The researchers investigated structural and functional connectivity of the mesolimbic reward pathway in the brains of children with and without ASD, using a technique called high angular resolution diffusion-weighted imaging along with functional MRI data. They analyzed brain wiring in 24 children with autism and 24 controls and examined functional connections in the brain in 16 children with autism and 20 controls as they looked at social or nonsocial images (pictures of faces or scenery). The team also performed scans on an additional 17 children with ASD and 17 controls to see if they could replicate their results. 

The researchers found that the density of nerve-fiber tracts in the mesolimbic reward pathway was lower in children with ASD than in controls. In comparison, they found no differences between the two groups when they examined an emotion-related brain pathway as a control. Among the children with ASD, lower density of nerve-fiber tracts correlated with greater social deficits. The researchers replicated these results in the second group of children they studied. 

In addition, children with ASD had weaker functional connections in the mesolimbic reward pathway than controls, and the degree of functional deficit correlated with the degree of social impairment. 

The researchers say their findings support the social motivation theory of autism, which proposes that social interaction is inherently less appealing to people with ASD than it is to their neurotypical peers. “It’s the first time we have had concrete brain evidence to support this theory,” Supekar says.


Citations

“Deficits in mesolimbic reward pathway underlie social interaction impairments in children with autism,” Kaustubh Supekar, John Kochalka, Marie Schaer, Holly Wakeman, Shaozheng Qin, Aarthi Padmanabhan, and Vinod Menon, Brain, July 17, 2018 (open access). Address: Kaustubh Supekar, 401 Quarry Road, Stanford, CA 94305, [email protected]

—and—

 “Key social reward circuit in the brain impaired in kids with autism,” Stanford News Center, July 16, 2018.