Atypical recruitment of medial prefrontal cortex in autism spectrum disorders: An fMRI study of two executive function tasks

Institute of Cognitive Neuroscience and Department of Psychology, University College London, London, UK.
Neuropsychologia (Impact Factor: 3.45). 02/2008; 46(9):2281-91. DOI: 10.1016/j.neuropsychologia.2008.03.025
Source: PubMed

ABSTRACT Recent studies have suggested an uneven profile of executive dysfunction in autism spectrum disorders (ASD). For example, some authors have reported deficits on newly developed tests of executive function sensitive to rostral prefrontal function, despite spared, or even superior, performance on other tests. We investigated the performance of a group of high-functioning participants with ASD (N=15) and an age- and IQ-matched control group (N=18) on two executive function tests, whilst undergoing functional magnetic resonance imaging (fMRI). Behaviourally, there were no significant differences between the two groups. In a classical test of executive function (random response generation), BOLD signal differed between the groups in the cerebellum but not in the frontal lobes. However, on a new test of executive function (selection between stimulus-oriented and stimulus-independent thought), the ASD group exhibited significantly greater signal-change in medial rostral prefrontal cortex (especially Brodmann Area 10) in the comparison of stimulus-oriented versus stimulus-independent attention. In addition, the new test (but not the classical test) provided evidence for abnormal functional organisation of medial prefrontal cortex in ASD. These results underline the heterogeneity of different tests of executive function, and suggest that executive functioning in ASD is associated with task-specific functional change.

  • Source
    Executive functioning: Role in early learning processes, impairments in neurological disorders and impact of cognitive behavior therapy (CBT)., Edited by K. P. Bennett, 01/2014: chapter Executive function in infants born preterm with varying birth weights and morbidities at emerging adulthood.: pages 81-114; Nova Science Publishers., ISBN: 978-1-63321-193-3
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Theory of mind ('ToM') tasks elicit highly reliable neural activity across individuals and experimental paradigms. We compared activity in a very large sample of neurotypical ('NT', N=477) individuals, and a group of high functioning individuals with autism spectrum disorders ('ASD', n=27), using both region of interest ('ROI') and whole-brain analyses. Although ToM activity showed significant and reliable individual differences, these differences were not explained by participant gender or age, or most experimental parameters. Furthermore, there were no differences between ASD and NT individuals. These results imply that the social cognitive impairments typical of ASD can occur without gross changes in the size or response magnitude of ToM brain regions.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Autistic Spectrum Disorders (ASDs) are a set of complex developmental disabilities defined by impairment in social interaction and communication, as well as by restricted interests or repetitive behaviors. Neuroimaging studies have substantially advanced our understanding of the neural mechanisms that underlie the core symptoms of ASDs. Nevertheless, a number of challenges still remain in the application of neuroimaging techniques to the study of ASDs. We review three major conceptual and methodological challenges that complicate the interpretation of findings from neuroimaging studies in ASDs, and that future imaging studies should address through improved designs. These include: (1) identification and implementation of tasks that more specifically target the neural processes of interest, while avoiding the confusion that the symptoms of ASD may impose on both the performance of the task and the detection of brain activations; (2) the inconsistency that disease heterogeneity in persons with ASD can generate on research findings, particularly heterogeneity of symptoms, symptom severity, differences in IQ, total brain volume, and psychiatric comorbidity; and (3) the problems with interpretation of findings from cross-sectional studies of persons with ASD across differing age groups. Failure to address these challenges will continue to hinder our ability to distinguish findings that outline the causes of ASDs from brain processes that represent downstream or compensatory responses to the presence of the disease. Here we propose strategies to address these issues: 1) the use of simple and elementary tasks, that are easier to understand for autistic subjects; 2) the scanning of a more homogenous group of persons with ASDs, preferably at younger age; 3) the performance of longitudinal studies, that may provide more straight forward and reliable results. We believe that this would allow for a better understanding of both the central pathogenic processes and the compensatory responses in the brain of persons suffering from ASDs.
    Behavioral and Brain Functions 03/2010; 6:17. DOI:10.1186/1744-9081-6-17 · 2.00 Impact Factor