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"The communication between the frontal and
posterior areas of the social brain network is impaired in autism, making it
difficult to understand the intentions of others," said the study's senior
author, Marcel Just, the D.O. Hebb professor of
psychology at Carnegie Mellon.
The study is the first to measure the synchronization between the brain areas
that make up the Theory of Mind (ToM) network, which is responsible for
processing the intentions and thoughts of others. It is the first to provide
such concrete evidence of faulty social network connections.
To measure the ToM network's effectiveness, the researchers asked 12
high-functioning autistic adults and 12 control participants to view animations
of interacting geometric figures, an example of which can be viewed at
www.ccbi.cmu.edu/reprints/reprints.htm.
Participants then were asked to select the word from several choices that best
described the interaction. For example, a large triangle would nudge a small
triangle to move outside its enclosure, and the correct word choice would be
"persuading." The control subjects were consistently better at inferring the
intention from the action than the participants with autism were.
While the study participants were performing the task, the researchers used
functional magnetic resonance imaging (fMRI) to measure activation levels in all
of the cortical areas that compose the ToM network. Specifically, they
simultaneously examined activation levels in several frontal and posterior brain
regions to determine the synchronization levels in the network. The
synchronization was reliably lower in the group with autism.
Furthermore, the autistic participants' brains showed much lower activation
levels than their counterparts in the frontal regions. These measures of brain
activity in autism, such as the activation level in the posterior part of the
ToM network (located approximately behind one's right ear), were correlated with
how well each autism participant performed in the Happe's Strange Story Test - a
pencil-and-paper assessment of an individual's understanding of non-literal
statements, such as figures of speech.
"This study offers compelling evidence that a lack of synchronization in the
Theory of Mind network is largely responsible for social challenges in autism,"
said Just, director of Carnegie Mellon's
Center for Cognitive Brain Imaging. "That evidence can provide the
foundation for therapies that are more useful than current approaches."
The findings have the potential to guide the development of theoretically based
interventions for autism that could target this particular shortfall, for
example, by focusing on games and activities that would strengthen the
connections. Eventually, it might be possible to tailor autism therapies to the
brain communication deficit on a case-by-case basis. Measuring the connectivity
before and after an intervention also could be used to determine effectiveness.
The research was supported by a Collaborative Program of Excellence in Autism
grant from NICHD (National Institute of
Child Health and Human Development) and the Cure Autism Now grant awarded to the
study's lead author, Rajesh K. Kana, now an assistant professor of psychology at
the University of Alabama at Birmingham.
Additional study co-authors include Timothy Keller and Vladimir Cherkassky of
Carnegie Mellon, and Nancy J. Minshew of the
University of Pittsburgh School of
Medicine.
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