Brains of people with autism recall letters of the alphabet in brain areas
dealing with shapes
Finding supports theory
that autism results from failure of brain areas to work together
In contrast to people who do not have
autism, people with autism remember letters of the alphabet in a part of the
brain that ordinarily processes shapes, according to a study from a
collaborative program of the National Institute of Child Health and Human
Development of the National Institutes of Health.
The study was conducted by researchers in
the NICHD Collaborative Program of Excellence in Autism (CPEA) at the
University of Pittsburgh and Carnegie Mellon University. It supports a
theory by CPEA scientists that autism results from a failure of the various
parts of the brain to work together. In autism, the theory holds, these
distinct brain areas tend to work independently of each other. The theory
accounts for observations that while many people with autism excel at tasks
involving details, they have difficulty with more complex information.
The study and the theory are the work of
Marcel Just, Ph.D., Professor of Psychology at Carnegie Mellon University in
Pittsburgh, Pennsylvania and Nancy Minshew, M.D., Professor of Psychiatry
and Neurology at the University of Pittsburgh School of Medicine and their
colleagues.
The study is scheduled for on-line
publication November 29 in the journal Neuroimage, at
http://www.sciencedirect.com.
"This finding provides more evidence to
support a promising theory of autism," said Duane Alexander, M.D., Director
of the NICHD. "If confirmed, this theory suggests that therapies emphasizing
problem solving skills and other tasks that activate multiple brain areas at
the same time might benefit people with autism."
People with autism typically have
difficulty communicating and interacting socially with others. The old
saying "unable to see the forest for the trees" applies to people with
autism, describing how many of them excel at matters of detail, yet struggle
to comprehend the larger picture. For example, some children with autism may
become champions at spelling bees, but have difficulty understanding the
meaning of a sentence or a story.
"The language pattern in autism is a
microcosm for the disorder," Dr. Just said. "People with autism are good at
a lower level of analysis but have a deficit at the higher level."
In the current study, the researchers used
a brain imaging technique known as functional magnetic resonance imaging (fMRI)
to measure the brain activity of 14 individuals with high functioning autism
while they performed a simple memory task involving letters of the alphabet.
Specifically, the study volunteers were shown a sequence of letters. After
each letter, they were asked to name the letter that preceded it. In some
cases, they were asked to name the letter that appeared two letters
previously. The autism volunteers' brain activation patterns were compared
to a control group of people who did not have autism, but were of a similar
age and I.Q. level.
Both groups successfully completed the
task. However, the fMRI scans revealed different brain activation patterns
between the two groups. Compared to the control group, the volunteers with
autism showed more activation in the right hemisphere, or half, of the
brain, and less activation in the left hemisphere. The left hemisphere takes
the lead in processing letters, words and sentences, whereas the right
hemisphere plays a larger role in processing shapes and visual information.
Dr. Just said that the brain could
interpret letters either spatially, as geometric shapes, or linguistically,
by the names of the letters. The imaging data indicated that the volunteers
with autism remembered letters as shapes, while the control group remembered
them by their names.
The brain activation patterns of the two
groups also differed in other ways. While performing the task, the group
with autism showed less activation in the anterior, or front, parts of the
brain, and more activation in the posterior, or rear parts of the brain. Dr.
Just explained that the brain's anterior portions carry out higher-level
thinking and reasoning while the posterior portion is more involved with
perceiving details.
Compared to the control group, the
different brain areas of the people with autism were less likely to work in
synchrony (at the same time) while recalling the letters. Such
synchronization between brain areas takes place during many kinds of
higher-level thinking and analysis that prove difficult for many people with
autism.
These current findings provide evidence in
support of the theory developed by these researchers. Called the theory of
underconnectivity in autism, it maintains that autism results from a failure
of the brain's neurological wiring--the fibers of nervous system tissue that
interconnect the individual parts of the brain. Deprived of effective
connections, the different brain areas must work independently, sometimes
performing at a higher level individually than they do in people who do not
have autism. This may allow some people with autism to excel at spelling and
other detail-oriented tasks but make it difficult for them to comprehend
more complex material.
The researchers published their theory in
the July issue of Brain, in conjunction with the results of another fMRI
study of volunteers with autism. In that study, volunteers were asked a
question about a simple sentence that they had just read. When the people
with autism performed the task, their brains showed less synchronization
than did the brains of the control group. Moreover, the brains of the group
with autism had less activation in an anterior part of the brain that
integrates the words of a sentence, and more activation in a posterior brain
area that comprehends individual words.
Many behavioral therapies to treat autism
stress rote learning, Dr. Minshew explained. Such strategies are helpful,
particularly early in a child's development. However, if the theory of
underconnectivity proves valid, therapies that stimulate brain areas to work
in synchrony might also offer some benefit. Such therapies might stress
problem solving skills and creative thinking, and attempt to foster
flexibility in thinking.
Dr. Just noted that more evidence to
support the theory might come from the group's on-going studies of other
cognitive abilities. The researchers are attempting to determine if
underconnectivity is a general feature of the brain in autism, and are using
brain imaging studies to examine the brain's white matter in people with
autism. White matter is the part of the brain that consists of the larger
neurological connections spanning different parts of the brain.
The NICHD is part of the National
Institutes of Health (NIH), the biomedical research arm of the federal
government. NIH is an agency of the U.S. Department of Health and Human
Services. The NICHD sponsors research on development, before and after
birth; maternal, child, and family health; reproductive biology and
population issues; and medical rehabilitation. NICHD publications, as well
as information about the Institute, are available from the NICHD Web site,
http://www.nichd.nih.gov, or from the
NICHD Information Resource Center, 1-800-370-2943; e-mail
NICHDInformationResourceCenter@mail.nih.gov.
Public
release date: 29-Nov-2004
Contact: Marianne Glass Miller or Bob Bock
301-496-5133
NIH/National
Institute of Child Health and Human Development
Go Top
"I know of nobody who is purely Autistic or purely neurotypical.
Even God had some Autistic moments, which is why the planets all spin."
~ Jerry Newport