AUTISM SKEWS DEVELOPING BRAIN WITH SYNCHRONOUS MOTION AND SOUND
Lip-Sync Could Explain Staring at People's Mouths

Individuals with autism spectrum disorders (ASD)
(http://www.nimh.nih.gov/health/topics/autism-spectrum-disorders-pervasi
ve-developmental-disorders/index.shtml) tend to stare at people's mouths
rather than their eyes. Now, an NIH-funded study in 2-year-olds with the
social deficit disorder suggests why they might find mouths so
attractive: lip-sync-the exact match of lip motion and speech sound.
Such audiovisual synchrony preoccupied toddlers who have autism, while
their unaffected peers focused on socially meaningful movements of the
human body, such as gestures and facial expressions.

"Typically developing children pay special attention to human movement
from very early in life, within days of being born. But in children with
autism, even as old as two years, we saw no evidence of this," explained
Ami Klin, Ph.D., of the Yale Child Study Center, who led the research.
"Toddlers with autism are missing rich social information imparted by
these cues, and this is likely to adversely affect the course of their
development."

Klin, Warren Jones, and colleagues at Yale, report the findings of their
study, funded in part by the National Institute of Health's National
Institute of Mental Health, online March 29, 2009 in the journal Nature.

For the first time, this study has pinpointed what grabs the attention
of toddlers with ASDs," said NIMH Director Thomas R. Insel, M.D. "In
addition to potential uses in screening for early diagnosis, this line
of research holds promise for development of new therapies based on
redirecting visual attention in children with these disorders."

A eureka moment in the research came when researchers followed up on a
clue from children's responses to audiovisual synchrony embedded in a
nursery rhyme cartoon.

While it was known that people with autism do not spontaneously orient
to social signals, it was unclear what early-emerging mechanism may
contribute to that. Nor was it clear exactly what they were attending to
instead. To find out, Klin, Jones and colleagues tracked the eye
movements of two-year-olds with and without the disorder while they
looked at cartoon animations on split-screen displays.

The researchers borrowed a technique from the video game industry,
called motion capture. They then reduced the movements to only points of
light at each joint in the body, like animated constellations. These
cartoons played normally - upright and forward - on one half of the
screen, but upside-down and in reverse on the other half. The inverted
presentation engages different brain circuits and is known to disrupt
perception of biological motion in young children. The normal soundtrack
of the actor's voice, recorded when the animations were made,
accompanied the presentations.

Eye-tracking data initially showed that 21 toddlers with ASD had no
preference for the upright animations, looking back and forth between
the two. By contrast, 39 typically-developing toddlers and 16
developmentally delayed but non-autistic toddlers clearly preferred the
upright animations.

However, responses to one animation didn't fit the pattern. The toddlers
with ASD changed their behavior and shifted their attention to the
upright figure as it played a game of pat-a-cake, where the figure claps
his hands repeatedly. In this animation (see movie below), unlike the
others, the movements of the points of light actually cause the clapping
sound. This physical synchrony-dots colliding to produce a clapping
sound-only existed on the upright side of the screen, because the
inverted figure played in reverse and its motions weren't in sync with
the soundtrack. The children with ASD chose the upright figure 66
percent of the time, a strong preference.

This clue led the researchers to suspect that what initially appeared to
be random viewing by the ASD toddlers might actually reflect preference
for audiovisual synchronies that were less obvious than the clapping. So
they re-analyzed the data, factoring in more subtle synchronous changes
in motion and sound.

"Audio-visual synchronies accounted for about 90 percent of the
preferred viewing patterns of toddlers with ASD and none of unaffected
toddlers," said Jones. "Typically-developing children focused instead on
the most socially relevant information."

A follow-up experiment using new animations optimized for audiovisual
synchrony confirmed these results.

Klin, Jones, and colleagues also recently reported
(http://www.nimh.nih.gov/science-news/2008/lack-of-eye-contact-may-predi
ct-level-of-social-disability-in-two-year-olds-with-autism.shtml) that
children with autism look more at peoples' mouths than eyes as early as
age 2. Since the mouth is the facial feature with most audiovisual
synchrony - lip motion with speech sound - the researchers propose that
their new findings offer a likely explanation for this phenomenon.

"Our results suggest that, in autism, genetic predispositions are
exacerbated by atypical experience from a very early age, altering brain
development," said Klin. "Attention to biological motion is a
fundamental mechanism of social engagement, and in the future, we need
to understand how this process is derailed in autism, starting still
earlier, in the first weeks and months of life."

NIMH is funding a related research project of Klin and Jones' that
explores related behaviors in infants who have older siblings already
diagnosed with ASD and who, because of the genetic heritability risk in
autism, have greater risk of also developing the condition.

Also participating in the research were: David Lin, now at Harvard
Medical School; Phillip Gorrindo, now at Vanderbilt University; Gordon
Ramsay, Ph.D., Haskins Laboratories. The study was funded through the
NIH's STAART Program (Studies To Advance Autism Research & Treatment).

Eye-tracking data shows where toddlers in each of three groups were
looking during the Pat-a-Cake animation. It plays upright and forward on
the left side of screens, upside down and in reverse on the right side.
Red cross indicates where the child was looking. Toddler with autism is
focused on audiovisual synchrony of hands clapping, while typically
developing and developmentally delayed toddlers focus on face.

Pat-a-cake animation, with audio playing at half-speed and color scale
indicating levels of audiovisual synchrony in child with autism. The
hands clapping show the highest levels of audiovisual synchrony (red) in
the figure on the right, which played upright and forward. Motion was
out of sync with the sound track in the figure on the left, because it
played upside down and in reverse.

The National Institute of Mental Health (NIMH) mission is to reduce the
burden of mental and behavioral disorders through research on mind,
brain, and behavior. More information is available at the NIMH website,
<http://www.nimh.nih.gov>.

The National Institutes of Health (NIH) -- The Nation's Medical Research
Agency -- includes 27 Institutes and Centers and is a component of the
U.S. Department of Health and Human Services. It is the primary federal
agency for conducting and supporting basic, clinical and translational
medical research, and it investigates the causes, treatments, and cures
for both common and rare diseases. For more information about NIH and
its programs, visit <www.nih.gov>.
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Reference: Klin A, Lin DJ, Gorrindo P, Ramsay G, Jones W. Two-year-olds
with autism fail to orient toward human biological motion but attend
instead to non-social physical contingencies. 2009 "Nature."