BRAIN ACTIVATION DURING COGNITIVE STIMULATION WITH THE WISCONSIN CARDSORTING TEST - A FUNCTIONAL MRI STUDY ON HEALTHY-VOLUNTEERS AND SCHIZOPHRENICS

It has been demonstrated by single photon emission computed tomography (SPECT) and positron emission tomography (PET) that frontal brain reg ions are stimulated during performance of the Wisconsin Card Sorting T est (WCST). The WCST is also regarded as one of the standard tests for the assessment of frontal activity in brain imaging studies of schizo phrenia. In this study cerebral activation was assessed by means of fu nctional magnetic resonance imaging (fMRI). In healthy volunteers WCST stimulation resulted in a right lateralized frontal activation. In 13 chronic schizophrenics on stable neuroleptic medication, a lack of ac tivation in the right prefrontal cortex and - as a trend - an increase d left temporal activity during execution of the WCST was noted compar ed to controls. Since a one-slice technique was used, no information a bout the activation pattern in adjacent brain regions was obtained. Ho wever, as fMRI possesses a superior spatial resolution compared to SPE CT and PET, the anatomical localization of the activation effect in th e measured slice can be defined more precisely. Beside these methodolo gical considerations, the results are discussed in relation to prior f indings of a reduced ability of schizophrenics to coordinate cerebral function. (C) 1997 Elsevier Science Ireland Ltd.