Neuropsychological and ocular motor studies of schizophrenia

Abstract

In the present thesis information processing deficits in schizophrenia are investigated with respect to task and disorder specificity, clinical correlates and brain (dys)function. To this end neuropsychological (studies 1-3) and oculomotor studies (studies 4-7) were conducted.Study 1 compared the neuropsychological profiles of patients with schizophrenia and depression. In study 2, correlations between cognitive functioning and symptoms of schizophrenia were investigated. Magnetoencephalographic (MEG) spectral analyses (study 3) revealed an increase in high-frequency brain activity (gamma band) over left fronto-temporal areas in healthy subjects. In schizophrenia patients this increase was either absent or reversed in laterality with the maximum over right fronto-temporal areas.The ocular motor studies revealed normal fixation stability and normal generation of refixation saccades in schizophrenia, implying adequate cerebellar and brainstem functioning (studies 4 and 5). But schizophrenia patients had considerable inhibition deficits and deficits in visuo-spatial working memory (study 5) indicating inadequate frontal lobe functioning. Better attention and auditory working memory is correlated with better visuo-spatial working memory (study 6).Finally, the preparatory activity before pro- and antisaccades in healthy people and schizophrenia patients was investigated using realistic MEG-source modelling (study 7). Here, frontal inhibitory deficits and deficits in right hemispheric activation of the dorsal attentional system were observed in schizophrenia patients prior to antisaccades. This lack of activation was particularly evident before antisaccades to the left, pointing to a hemispheric abnormalitiy in inhibitory and attentional control.The results are discussed with respect to their compatibility with currently influential models of information processing in schizophrenia.