A new EEG-based study by researchers at Albert Einstein College of Medicine of Yeshiva University has provided concrete evidence that children with autism spectrum disorders (ASD) process sensory information such as sound, touch, and vision differently than typically developing children. The results appear in the August 17 online issue of Autism Research. Included in this report is a video interview with the lead researcher who summarizes these results.
The study supports decades of clinical and anecdotal observations that individuals with ASD have difficulty coping with multiple sources of sensory information. The Einstein finding offers new insights into autism and could lead to objective measures for evaluating the effectiveness of autism therapies.
“One of the classic presentations of autism is the child in the corner with his hands over his ears rocking back and forth trying to block out the environment,” said senior author Sophie Molholm, Ph.D., associate professor in the Dominick P. Purpura Department of Neuroscience and of pediatrics. “People have long theorized that these children might not be integrating information across the senses very well. If you have all these sights and sounds coming at you but you can’t put them together in a meaningful way, the world can be an overwhelming place.”
The theory that autistic kids have trouble processing multisensory information has not been reliably supported by behavioral studies, and has rarely, if at all, been tested using measures of brain activity. Over the last few years, Dr. Molholm and her colleagues have been refining methods for measuring multisensory integration (MSI) using brainwave electroencephalogram (EEG) recordings.
In the current study, MSI was measured in 17 ASD children, ages 6 to 16, and 17 typically developing children matched for age and non-verbal IQ. The children watched a silent video of their choice while they were presented with unrelated sounds and vibrations. The auditory and vibrational stimuli were presented separately (creating so-called unisensory conditions) and then together (multisensory condition), which acted as the researchers’ index of MSI. The children’s EEG responses to the unisensory conditions were summed and compared to their EEG responses to multisensory conditions.
The responses of the typically developing children to the multisensory stimuli exceeded the sum of their responses to the unisensory stimuli – an indication of healthy MSI, according to the researchers. In the ASD children, by contrast, the differences between the sum of children’s unisensory responses and their MSI responses were not nearly as pronounced, indicating that these kids were not integrating multisensory information as effectively.
“Our data makes a compelling case, at least for these conditions, that there are differences in multisensory integration between the two groups,” said Dr. Molholm.
After our nerves are stimulated, “sensory information arrives in the brain’s cortex within 20 milliseconds (ms), or 20/1000ths of a second,” said co-author John Foxe, Ph.D., professor in the Dominick P. Purpura Department of Neuroscience and of pediatrics and director of research of the Children’s Evaluation and Rehabilitation Center at Einstein. “Then it takes an additional 100 to 200 ms for the brain to integrate information arriving from different senses, since many brain regions are involved in analyzing it.”
Dr. Molholm and Dr. Foxe’s study, “Multisensory processing in children with autism: high-density electrical mapping of auditory-somatosensory integration,” appears in the August 17 online issue of Autism Research. The first author is Natalie Russo, Ph.D., a post-doctoral fellow with Dr. Molholm and Dr. Foxe. The other co-authors are doctoral students Alice Brandwein and Ted Altschuler, and Hilary Gomes, Ph.D., a professor in psychology at the City College of New York.
Material adapted from Albert Einstein College of Medicine.