Children with autism have less flexible brains than those without the developmental disorder, researchers at Stanford University said Tuesday. The discovery brings scientists closer to understanding the neural roots of autistic behavior — and could give rise to new therapies, they said.

Already, the scientists had mapped connections between disparate parts of autistic children's brains using functional magnetic resonance imaging, or fMRI. Those findings, reported in November, showed "hyperconnectivity" in autistic brains, like a highway interchange with too many on ramps. The more tightly woven the web of brain circuits, the more severe a child's social deficits.

In the new study, they were interested in that same network of connections, which are responsible for decision-making, social function, and reading cues from the environment. "We wanted to test the idea that a flexible brain is necessary for flexible behaviors," lead author Lucina Uddin, who conducted the research as a post-doctoral scholar at Stanford, said in a statement. In other words, are trademark symptoms of autism, such as repetitive behaviors and obsessing over a single subject, related to rigid connections?

Again using fMRI scans, they watched the brains of 34 kids with autism and 34 without as they solved simple mathematics and face-recognition quizzes. Both groups performed equally well at solving the problems; the only differences were in their brains. "What we found was that across a set of brain connections known to be important for switching between different tasks, children with autism showed reduced 'brain flexibility' compared with typically developing peers," Uddin said.

The brains of the children without autism changed when switching from a resting to a working state, essentially turning on in order to perform a task. The brains of the autistic children toggled less, and the more rigid the connections, the more severe were the child's symptoms. "The fact that we can tie this neurophysiological brain-state inflexibility to behavioral inflexibility is an important finding because it gives us clues about what kinds of processes go awry in autism," said Vinod Menon, a Stanford psychologist and senior author of the study.

One in every 68 children in the U.S. has autism. This research could help others test the effectiveness of different therapies by targeting treatments that encourage brain flexibility. "We're making progress in identifying a brain basis of autism, and we're starting to get traction in pinpointing systems and signaling mechanisms that are not functioning properly," Menon said. "This is giving us a better handle both in thinking about treatment and in looking at change or plasticity in the brain."

Source: Uddin L, Supekar K, Menon V, et al. Cerebral Cortex. 2014.