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Neocortical system abnormalities in autism: an fMRI study of spatial working memory
B Luna1, N J Minshew, K E Garver
1Department of Psychiatry, University of Pittsburgh, Carnegie Mellon University, Pittsburgh, PA 15213, USA. lunab@msx.upmc.edu
Neurology
|September 26, 2002
Summary
Autism is linked to reduced brain activity in key areas like the prefrontal cortex during spatial working memory tasks. This suggests prefrontal circuitry abnormalities contribute to cognitive deficits in autism.
Area of Science:
- Neuroscience
- Cognitive Science
- Autism Research
Background:
- Autism Spectrum Disorder (ASD) is characterized by social and communication deficits, alongside restricted interests and repetitive behaviors.
- Executive function impairments, particularly in spatial working memory, are frequently observed in individuals with autism.
- The neural underpinnings of these cognitive deficits, especially involving prefrontal cortex function, require further elucidation.
Purpose of the Study:
- To investigate the hypothesis that spatial working memory deficits in autism stem from prefrontal circuitry abnormalities.
- To compare brain activation patterns during a spatial working memory task between autistic and typically developing individuals.
Main Methods:
- Functional magnetic resonance imaging (fMRI) at 3 Tesla was employed.
- Eleven individuals with autism (non-mentally retarded) and six healthy volunteers participated.
- Participants performed an oculomotor spatial working memory task and a visually guided saccade task.
Main Results:
- Autistic subjects showed significantly reduced activation in dorsolateral prefrontal cortex (Brodmann area 9/46) and posterior cingulate cortex (BA 23) during the spatial working memory task compared to controls.
- Activation was not significantly reduced in other brain regions crucial for spatial working memory, including cortical eye fields, anterior cingulate cortex, insula, basal ganglia, thalamus, and lateral cerebellum.
- No significant differences in brain activation were observed between groups during the visually guided saccade task.
Conclusions:
- Abnormalities in neocortical circuitry, specifically decreased activation in prefrontal and posterior cingulate regions, may underlie executive cognitive process impairments in autism.
- These findings highlight the role of prefrontal cortex dysfunction in spatial working memory deficits observed in autism spectrum disorder.