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

Sam J Gilbert,Geoffrey Bird,Rachel Brindley,Christopher D Frith,Paul W Burgess

doi:10.1016/j.neuropsychologia.2008.03.025

Sam J Gilbert, Geoffrey Bird + Show 3 more

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https://doi.org/10.1016/j.neuropsychologia.2008.03.025

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Journal: Neuropsychologia	Publication Date: Apr 10, 2008
Citations: 188	License type: cc-by

Affiliation: University College London, Aarhus University

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.

Highlights

Along with well-documented abnormalities in social interaction, communication, perception and attention (Frith, 2003), a large number of recent studies have provided evidence for disruption of executive functions in autism spectrum disorders (ASD; see e.g. Hill, 2004a,b; Ozonoff, Pennington, & Rogers, 1991; Ozonoff & Jensen, 1999; Russell, 1997; Russo et al, 2007)
Subsequent studies have suggested that these tasks, which depend upon behavioural organisation within relatively ill-constrained or ill-structured situations, are sensitive to lesions within the rostral prefrontal cortex, approximating Brodmann Area (BA) 10 (Burgess, 2000; Burgess, Veitch, Costello, & Shallice, 2000; see Goel & Grafman, 2000)
Recent evidence suggests that executive deficits in high-functioning adults with ASD may be apparent in new tests of executive function involving multitasking, rather than more constrained classical tests of executive function

Summary

Introduction

Along with well-documented abnormalities in social interaction, communication, perception and attention (Frith, 2003), a large number of recent studies have provided evidence for disruption of executive functions in autism spectrum disorders (ASD; see e.g. Hill, 2004a,b; Ozonoff, Pennington, & Rogers, 1991; Ozonoff & Jensen, 1999; Russell, 1997; Russo et al, 2007). A consistent finding has been that participants with ASD tend to show deficits on only a restricted set of executive function tests, with preserved or superior performance in other domains (Hill & Bird, 2006; Minshew, Goldstein, & Siegel, 1997). This contrasts with other populations, who may be more likely to show more widespread deficits, such as those with schizophrenia (Bilder et al, 2000). The uneven profile of performance seen in studies that have investigated executive functions in ASD argues against a “deficit model” of the processing differences between participants with ASD and controls, and instead suggests that ASD may be better characterised by disruption or reorganisation of specific brain systems, rather than more generalised impairment (Minshew et al, 1997)

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