Identification of neuroanatomical substrates of set-shifting ability: evidence from patients with focal brain lesions

Department of Psychology, University College of Science and Technology, 92 APC Road, Calcutta, India.
Progress in brain research (Impact Factor: 2.83). 02/2008; 168:95-104. DOI: 10.1016/S0079-6123(07)68008-X
Source: PubMed


This work concerns the investigation of executive functions in patients with focal brain lesion. In order to identify the underlying substrates for executive functions, 54 patients with focal cortical (n=30), subcortical (n=13) and cerebellar damage (n=10) (M=9; F=1) in the age range of 24-65 years with a minimum of Class V education have been investigated. The patients were admitted to the Department of Neuromedicine of Bangur Institute of Neurology, Calcutta. Each patient with focal lesion was matched with a healthy normal subject controlling for age and education. The socio-economic background was also taken into consideration. Controls were selected from the families of other patients admitted to the institution and also from individuals who volunteered to act as controls. Here too, rigid criteria have been followed to select the normals. Mini Mental State Examination (MMSE) and General Health Questionnaire (GHQ) were administered to screen out the neurological and psychiatric abnormalities in selection of normal control and Wisconsin Card Sorting Test (WCST) was administered to find out the executive function, in terms of set-shifting ability. Since standard anatomical groupings can obscure more specific brain-behavior relations, group-comparison design does not always allow determination of the effective lesion responsible for a particular deficit (Godefroy et al., 1998). The Classification and Regression Tree (CART) analysis has been used to determine the brain-behavior relationships. The result reveals that the frontal lobes are essential determinants of set-shifting capacity. However, for optimal execution of set-shifting function, the frontal lobes require participation of other cortical, subcortical and cerebellar regions. The result has been discussed in the light of the existing theories and research reports.

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    • "The orbitofrontal cortex in rhesus monkeys is also involved in associative learning, and processes reward and affect information (Meunier et al., 1997; Wallis and Miller, 2003). In humans, fMRI studies using normal controls, patients with frontal brain lesions, and patients with psychiatric illnesses related to frontal lobe dysfunction, such as schizophrenia, have also demonstrated a correlation between frontal lobe activity and WCST performance (Rogers et al., 2000; Monchi et al., 2001; Bonilha et al., 2008; Mukhopadhyay et al., 2008). In addition, it is important to note the involvement of cerebellar areas in the present cognitive task, as it is likely that the contribution of other cortical and cerebellar regions is critical for optimal functioning in this cognitive domain (Berman et al., 1995; Moore et al., 2009). "
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    • "Moreover, many clinical studies show that damage in non-frontal (Leskela et al., 1999; van den Broek, Bradshaw, & Szabadi, 1993) or diffuse damage in frontal and non-frontal regions (Anderson, Damasio, Jones, & Tranel, 1991; Axelrod et al., 1996) both affect WCST performance. More specifically , many authors have reported that damage to temporal (Corcoran & Upton, 1993; Giovagnoli, 2001; Hermann, Wyler, & Richey, 1988; Horner, Flashman, Freides, Epstein, & Bakay, 1996; Strauss, Hunter, & Wada, 1993), subcortical (Mukhopadhyay et al., 2008), hippocampal (Corcoran & Upton, 1993; Giovagnoli, 2001; Igarashi et al., 2002), and even cerebellar regions (Mukhopadhyay et al., 2008) cause similar impairments on WCST performance as those subsequent to frontal lobe lesions. 3. Review of neuroimaging studies Modern functional neuroimaging techniques have been used in many studies to describe changes in brain activation during WCST performance. "
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    ABSTRACT: For over four decades the Wisconsin Card Sorting Test (WCST) has been one of the most distinctive tests of prefrontal function. Clinical research and recent brain imaging have brought into question the validity and specificity of this test as a marker of frontal dysfunction. Clinical studies with neurological patients have confirmed that, in its traditional form, the WCST fails to discriminate between frontal and non-frontal lesions. In addition, functional brain imaging studies show rapid and widespread activation across frontal and non-frontal brain regions during WCST performance. These studies suggest that the concept of an anatomically pure test of prefrontal function is not only empirically unattainable, but also theoretically inaccurate. The aim of the present review is to examine the causes of these criticisms and to resolve them by incorporating new methodological and conceptual advances in order to improve the construct validity of WCST scores and their relationship to prefrontal executive functions. We conclude that these objectives can be achieved by drawing on theory-guided experimental design, and on precise spatial and temporal sampling of brain activity, and then exemplify this using an integrative model of prefrontal function [i.e., Miller, E. K. (2000). The prefrontal cortex and cognitive control. Nature Reviews Neuroscience, 1, 59-65.] combined with the formal information theoretical approach to cognitive control [Koechlin, E., & Summerfield, C. (2007). An information theoretical approach to prefrontal executive function. Trends in Cognitive Sciences, 11, 229-235.].
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    Journal of the International Neuropsychological Society 10/2008; 14(5):862-8. DOI:10.1017/S1355617708081125 · 2.96 Impact Factor
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