Autism Linked to Multisensory Integration

A new 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 study, which appears in the August 17 online issue of
Autism Research, supports decades of clinical and anecdotal

An EEG cap is
used to measure the brain's response to sensory stimuli. (Credit: Photo
courtesy of Albert Einstein College of

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."
In this study, the differences between the typically developing and ASD
children were most striking for that time interval in which multisensory
stimuli is normally processed. "We saw robust MSI in the typically
developing kids from 100 and 200 ms after sensory stimulation reached the
brain's cortex," said Dr. Foxe. "But in the ASD kids, MSI occurred
significantly later -- at about 310 ms -- and at a much lower level."
"This doesn't mean that the children with ASD didn't integrate the
information at all," he added. "It does mean that they didn't integrate it
as effectively as they should have, given their age and maturity. They may
go on to integrate well later in life. We don't know. This is a single
slice of the developmental trajectory."
"This was a much-needed study of multisensory integration in autism,"
said Barry E. Stein, Ph.D., professor and chair of neurobiology &
anatomy at Wake Forest University School of Medicine, who was not involved
in the Einstein study. "Using simple logic and standard techniques for
electrically mapping the brain, the authors have identified defects in the
way ASD individuals synthesize cues from different senses. In doing so,
they have not only helped confirm the insights of parents and clinicians,
but they've improved our understanding of how the behavioral differences
in children with ASD may result from sensory anomalies."
"Today, there's a cottage industry -- actually more like a
military-industrial complex -- for multisensory integration therapies for
children with autism," said Dr. Foxe. "A lot of parents' hard-earned cash
goes into these interventions, all in the absence of actual empirical
evidence that there is anything wrong with MSI in these children or that
these therapies do any good."
The researchers are currently evaluating MSI in children from 6 years
of age through early adulthood to better understand the developmental
trajectory of multisensory integration. They also plan to study MSI in
lower-functioning ASD children. "This experimental paradigm is especially
good for that, because it makes so little demand on the kids," said Dr.
Foxe. "As you can imagine, asking them to do tasks doesn't work very
Support for this research was provided by Cure Autism Now, the National
Institute of Mental Health, the Wallace Research Foundation and the
Canadian Institute of Health Research.
Editor's Note: This article is not intended to provide medical advice,
diagnosis or treatment. source :

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