Study participants with autism showed greater activation in areas near
the intraparietal sulcus (circled regions) than normal control participants
during the processing of low-imagery sentences. The areas near the
intraparietal sulcus are associated with visual imagery.
Source: Marcel Just, Ph.D., Brain advance-access Internet
A decade ago a woman with autism wrote: "I think in pictures. Words
are like a second language to me. I translate both spoken and written words
into full-color movies, complete with sound, which run like a VCR tape in my
Thanks to neuroimaging, scientists are starting to confirm what this woman
and others with autism have claimed—that they tend to think
Last year, for example, an fMRI study headed by Nancy Minshew, M.D., a
professor of psychiatry and neurology at the University of Pittsburgh, and
Marcel Just, Ph.D., a professor of psychology at Carnegie Mellon University,
showed that when individuals with autism attempt to recall letters of the
alphabet, their brains process the stimuli differently from the brains of
nonautistic individuals. The former rely more on the parietal regions, which
are involved in visuospatial processing, whereas the latter depend more on the
left prefrontal cortex, which is involved in language processing
(Psychiatric News, February 4, 2005).
Now a new fMRI study conducted by the same group, and published on the
Brain advance-access Internet site on July 10, reveals that when
persons with autism attempt to comprehend sentences, they rally visual centers
in their brains to do so even if the sentences do not contain visual
For example, one of the low-imagery sentences used in the experiment was"
Addition, subtraction, and multiplication are all math skills."
As the control group comprehended this sentence, their left prefrontal cortex
was activated. But as the autism group comprehended this sentence, not only
their left prefrontal cortex, but their parietal regions were switched on as
Moreover, as the autistic prefrontal cortex and parietal regions process
language or engage in other cerebral challenges, they may be out of step with
each other, another investigation has found. It was conducted by the same
research team and was published on the Cerebral Cortex advance access
Internet site on June 13.
In this inquiry, fMRI was used to examine the brains of both autism
subjects and control subjects as they performed the Tower of London test. This
task involves moving three balls into a specified arrangement. It requires
planning and goal-management ability, using both the prefrontal cortex and the
parietal regions. In the control group, the prefrontal cortex and parietal
regions tended to function in synchrony—that is, increasing or
decreasing their activity at the same time—whereas in the autism group,
these two brain areas were less likely to do so.
This lack of synchronization between the prefrontal and parietal regions,
in turn, implies that it may be due to faulty white matter fiber connections
between them. The Cerebral Cortex study supports this supposition.
The largest white matter fiber tract in the brain is the corpus callosum,
which allows communication between the two sides of the brain. One part of the
corpus callosum is the genu. The genu was found to be smaller in the autism
group than in the control one, and the smaller the genu in the autism
subjects, the more out of sync their frontal and parietal regions were.
Of all their new findings, Just considers this to be the most important, he
told Psychiatric News. "The reason that this finding is
important—and rare—is that it makes a crucial link between [the
synchronization of activity between different brain areas] and the anatomical
white matter brain structure—corpus callosum—that carries the
communication between the areas. It is a crucial link between brain activation
and brain tissue in autism."
Indeed, when all of these findings are considered together, they make
Minshew, Just, and their group wonder whether a reduced white fiber
connectivity might underlie the neurological, psychological, and behavioral
symptoms that constitute the syndrome of autism. And if autism is truly due to
a failure of various brain regions to communicate with each other, it"
may one day provide the basis for improved treatments for autism that
stimulate communication between brain areas," Duane Alexander, M.D.,
envisions. He is director of the National Institute of Child Health and Human
Development. That institute, as well as the National Institute on Deafness and
Other Communication Disorders, funded the two studies.
Meanwhile, Minshew told Psychiatric News that these study results
help explain why individuals with autism can be so bright in specialized ways,
yet have trouble with problem-solving and understanding the gist of
things—they have the local brain connections to perform the former, but
not the widespread brain connections to carry out the latter.
"So in dealing with patients with autism," Minshew advised,"
say whatever you have to say as simply as possible. Don't give a lot of
examples and expect them to extract the concept [because the circuits that
handle these functions may not be working properly]. Also, don't expect them
to generalize from one experience to the next [for the same reason]. Use
facts, details, and their favorite interest to motivate them."
An abstract of "Sentence Comprehension in Autism: Thinking in
Pictures With Decreased Functional Connectivity" is posted at<http://brain.oxfordjournals.org/cgi/content/abstract/awl164v1>.
An abstract of "Functional and Anatomical Cortical Underconnectivity in
Autism: Evidence From an fMRI Study of an Executive Function Task and Corpus
Callosum Morphometry" is posted at<http://cercor.oxfordjournals.org/cgi/content/abstract/bhl006v1>.▪