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Suppression of Prepotent Motor Responses Implicate Frontostriatal Dysfunction in Schizophrenia and Its Subtypes

Published online by Cambridge University Press:  21 February 2012

Joanne Oram
Affiliation:
Cognitive Psychophysiology Laboratory, School of Psychology, The University of Queensland, Australia.
Gina M. Geffen*
Affiliation:
Cognitive Psychophysiology Laboratory, School of Psychology, The University of Queensland, Australia. geffen@psy.uq.edu.au
*
*Address for correspondence: Professor Gina Geffen, Edith Cavell Building, The Medical School, Herston Road, Brisbane QLD 4006, Australia.
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Abstract

Schizophrenia has been identified as a disorder of the frontostriatal system with impairments in both sustained and selective attention (Bradshaw, 2001). The Sustained Attention to Response Task (SART), which required occasional withholding of an ongoing frequent response when a specified digit occurred, was completed by patients with a clinical diagnosis of schizophrenia (N = 52) and matched controls (N = 46). Relative to controls, participants with schizophrenia responded less frequently and made more impulsive errors. Their correct responses were slower on average, with greater variability in timing. Speed of response was unrelated to neuroleptic medication dosage. The slow responses exhibited by patients with schizophrenia were interpreted as reflecting primarily motor frontostriatal circuit dysfunction, and dysfunction of the lateral orbitofrontal/anterior cingulate circuit is implicated in poor impulse control. To address the heterogeneity of symptoms in schizophrenia, symptom dimension scores (positive, negative and disorganised) were used to determine whether symptom dimensions were associated with differential performance on the SART. Higher negative symptoms were related to increased miss errors on the SART whereas higher disorganised and positive symptom scores were unrelated to performance on this measure. An association between negative symptoms and increased miss errors may be considered indicative of dysfunction of the anterior cingulate circuit, considered to be linked to response inattention, apathy, reduced initiative and focused attention. Implications of this research for understanding the neuroanatomical basis for schizophrenia and its subtypes are discussed.

Type
Articles
Copyright
Copyright © Cambridge University Press 2007

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