THE WISCONSIN CARD SORTING TEST AND THE ASSESSMENT OF FRONTAL FUNCTION - A VALIDATION-STUDY WITH EVENT-RELATED POTENTIALS

The Wisconsin Card Sorting Test (WCST) is generally regarded as the pr ototype of abstract reasoning task and has been routinely used to asse ss frontal lobe function in a variety of clinical and research context s. However, there are growing concerns that the WCST fails to discrimi nate frontal patients from those with lesions in other brain regions o r from normals. Event-related potentials (ERP) from frontal, fronto-te mporal, temporal, parietal and occipital areas were recorded during th e performance of a computerized version of the WCST in order to explor e frontal versus non-frontal ERP indexes during WCST activation. The t ask protocol was contrived to focus on the differences between early a nd late trials of each WCST series. Cognitive processes underlying the se two task conditions have been described as extradimensional and int radimensional shifts in attention, respectively. Differences between e arly and late WCST trials appeared as soon as 120 msec poststimulus an d were associated with a negative field potential centred at the front o-temporal region of the left hemisphere. Significantly larger amplitu des of the posterior P3b wave for late as compared with early WCST tri als also lent support to claims of a strong involvement of working mem ory mechanisms during WCST performance. Results are discussed in terms of the implications for the utility of ERP measures in clinical neuro psychology. (C) 1997 Elsevier Science Ltd.