A new study offers a glimpse of some of the cerebral "highways"
that people with autism may use when trying to remember letters of the
alphabet. It has found that when persons with autism try to recall letters
they have seen, they may perform as well as individuals without the disorder,
but even when their performance is comparable, they may tap brain areas not
deployed by the latter.
The investigation is in press with NeuroImage. The chief
investigator was Hideya Koshino. Ph.D., an associate professor of psychology
at California State University in San Bernardino.
The scientists used functional magnetic resonance imaging to visualize the
brain activity of 14 high-functioning autism individuals and 14 control
subjects who did not have autism while they tried to remember letters of the
alphabet. The control subjects were matched with the autism subjects on I.Q.,
age, gender, race, and socioeconomic status. The investigators also evaluated
the ability of both groups to remember the letters.
Although the autism group remembered as well as the control group, the
former used different brain areas to do so.
The autism group showed less activation in the left hemisphere frontal
regions than the control group. Verbal working memory is known to be related
to the left prefrontal cortex, whereas nonverbal working memory is linked with
the right prefrontal cortex. "Therefore, it is possible," the
researchers wrote, "that the autism group processed the letter stimuli
of the present study in a nonverbal fashion using visual codes, whereas the
control group processed them verbally."
Or to put it another way, the autism subjects probably saw each letter as
an object, not as a letter, Nancy Minshew, M.D., a professor of psychiatry and
neurology at the University of Pittsburgh and a co-author of the study, told
Psychiatric News. "They were not associating linguistic meaning
to it since they were not tapping into language areas."
The autism group also showed greater activation than the control group in
the right hemispheric parietal regions. "Together with the first point
that the autism group showed hypo-activation in the left prefrontal
cortex," the researchers wrote, "these results seem to indicate
that the autism group processed the letter stimuli as nonverbal,
Finally, the autism group demonstrated more activation than the control
group in the posterior brain, such as the left temporal and right temporal
regions. "This pattern might also be related to the
information-processing style of the participants with autism," the
investigators speculated, "suggesting that they relied on analysis of
lower-level visual features."
All together, these results add to the growing body of evidence implying
that people with autism think differently, Minshew said. The results also
insinuate that pictures might be an effective way of teaching the meaning of
letters to persons with autism.
The study was funded by the National Institute of Child Health and Human
An abstract of "Functional Connectivity in an fMRI Working
Memory Task in High-Functioning Autism" can be accessed at<www.sciencedirect.com>
by clicking on "Browse A-Z of Journals," "N," and then"