Diverse symptoms associated with autism could be explained by unreliable activity of neurons in the brain in response to basic, nonsocial sensory information, according to a study published by Cell Press on September 19th in the journal Neuron. The new findings suggest that autism is a disorder of general neural processing and could potentially provide an explanation for the origins of a range of psychiatric and neurological disorders.
"Within the autism research community, most researchers are looking for either a dysfunctional brain region or inadequate connections between brain regions," says lead study author Ilan Dinstein of Carnegie Mellon University. "We're taking a different approach and thinking about how a general characteristic of the brain could be different in autism--and how that might lead to behavioral changes."
Autism is a developmental disorder marked by social deficits, communication problems, and repetitive behaviors. Two previous studies suggested that the neural responses of individuals with autism are more variable than those of control subjects during visual and motor tasks. Building on this past evidence, Dinstein and his collaborators have now shown that multiple sensory systems within these individuals show noisy responses, suggesting that widespread behavioral abnormalities could arise from a basic dysfunction in neural processing that emerges during development.
In the study, adults with autism participated in functional magnetic resonance imaging experiments in which their brain activity was measured under three different conditions: while they watched moving dots on a screen, listened to tone beeps, and felt air puffs on their hands. The neural responses to all three types of sensory information were less reliable across trials in individuals with autism than in control subjects.
The findings suggest that autism could result from fundamental defects in general neural processing rather than a collection of independent problems that affect different brain regions. "Unreliable neural activity is a general property that could have a profound impact on the function of many brain systems and could underlie a range of cognitive and social abnormalities," says study author Marlene Behrmann of Carnegie Mellon University. "So we think that this problem could play a role not only in autism, but also potentially in other disorders such as epilepsy and schizophrenia."
Dinstein et al.: "Unreliable evoked responses in autism."
Video: Marlene Behrmann, Professor of Psychology, and IIan Dinstein, Postdoctoral Researcher, from Carnegie Mellon University's Department of Psychology discuss their study "Autistic Adults have Unreliable Neural Sensory Responses" publishing in Neuron.