Children with autism see simple movement twice as quickly as other children their age, and this hypersensitivity to motion may provide clues to a fundamental cause of the developmental disorder, according to a new study.
Such heightened sensory perception in autism may help explain why some people with the disorder are painfully sensitive to noise and bright lights. It also may be linked to some of the complex social and behavioral deficits associated with autism, says Duje Tadin, one of the lead authors on the study and an assistant professor of brain and cognitive sciences at the University of Rochester.
Such hypersensitive perception is the neural signature for a brain that is unable to dampen its response to sensory information, note the authors. This same increase in neural “excitability” is also found in epilepsy, which is strongly linked to autism. In fact, as many as one third of individuals with autism also have epilepsy. Normally, the brain puts the brakes on its responses to sound, taste, touch, and other stimuli when they become too intense.
What’s important about this dampening ability is that it’s a ubiquitous mechanism controlling how humans perceive the world. “If the processing of our vision, hearing, and other sensory systems is abnormal in some way, it will have a cascading effect on other brain functions,” says Carissa Cascio, assistant professor of psychiatry at Vanderbilt University, in whose lab the study was conducted. “You may be able to see better, but at some point the brain really is over responding. A strong response to high intensity stimuli in autism could be one reason for withdrawal.”
By contrast, in more complex tasks, like facial recognition, these enhancements become impairments. Likewise, autism is associated with deficits in perceiving motion patterns more complex than the simple moving bars used in this study, such as detecting walking and other biological movements.