Autistic Brains May Over- or Under-Synchronize

While autism spectrum disorder (ASD) has been studied for many years, there are still more questions than answers. For instance, some researchers into the brain functions of individuals on the autism spectrum have discovered a lack of synchronization between different parts of the brain that normally work in tandem. Meanwhile, other studies have found the exact opposite - over-synchronization in the brains of those with ASD.

A new study recently published in Nature Neuroscience, suggests that the various reports - of both over- and under-connectivity - may, in fact, reflect an interesting trend. The study was done by Avital Hahamy and Prof. Rafi Malach of the Weizmann Institute's Department of Neurobiology in Israel, working with Prof. Marlene Behrmann of Carnegie Mellon University, Pittsburgh, Pennsylvania. Prof. Rafael Malach's research is supported by the Murray H. and Meyer Grodetsky Center for Research of Higher Brain Functions, which he heads, and the Friends of Dr. Lou Siminovitch. Prof. Malach is the recipient of the Helen and Martin Kimmel Award for Innovative Investigation, and is the incumbent of the Barbara and Morris L. Levinson Professorial Chair in Brain Research.

To determine the concept of connectivity in ASD, the researchers analyzed data obtained from functional magnetic resonance imaging (fMRI) studies conducted while the subjects were at rest. Data had been collected from a large number of participants at multiple sites and assembled in the Autism Brain Imaging Data Exchange (ABIDE) database. "Resting-state brain studies are important, because that is when patterns emerge spontaneously, allowing us to see how various brain areas naturally connect and synchronize their activity," said Hahamy. A number of previous studies in Prof. Malach's group and others suggest that these spontaneous patterns may provide a window into individual behavioral traits, including those that stray from the norm.

Researchers did a comparison of the details of these intricate synchronization patterns. They discovered a significant difference between the control and ASD groups: The control participants' brains had substantially similar connectivity profiles across different individuals, whereas those with ASD showed a remarkably different characteristic. These tended to display much more unique patterns - each in its own, individual way. The researchers concluded that the synchronization patterns seen in the control group were "conformist" relative to those in the ASD group, which they termed "idiosyncratic."

The scientists offered a possible explanation for differences between the synchronization patterns in the autism and control groups: They might be a product of the ways in which individuals in the two groups interact and communicate with their environment. Hahamy said, "From a young age, the average, typical person's brain networks get molded by intensive interaction with people and the mutual environmental factors. Such shared experiences could tend to make the synchronization patterns in the control group's resting brains more similar to each other. It is possible that in ASD, as interactions with the environment are disrupted, each one develops a more uniquely individualistic brain organization pattern."

Because the researchers emphasized that this explanation is only tentative, they cautioned that much more research will be needed to fully uncover the range of factors that may lead to ASD-related idiosyncrasies. Additionally, they suggested that further research into how and when different individuals establish particular brain patterns could help in the future development of early diagnosis and treatment for autism disorders.

Image Credit: Weizmann Institute of Science