Saccadic paradigms and cognition in schizophrenia: a review
background Schizophrenia can be characterized by the presence of various cognitive dysfunctions. These can be easily investigated with saccadic paradigms. For most saccadic paradigms, the brain mechanisms involved are very well known. The saccadic performance of schizophrenic patients therefore, provides information about the function of certain brain areas, and possibly about brain dysfunctions underlying the disease process. Recent developments in neuroimaging research can contribute to this search for schizophrenia brain dysfunctions.
aims This literature study describes how the performance of schizophrenics differs from healthy controls on the four most widely used saccadic paradigms. For each of the paradigms new information about the neural mechanisms is added from neuroimaging studies. The saccadic abnormalities of schizophrenic patients are described in terms of brain dysfunctions. Finally, results on saccadic deficits of other patient groups are reported.
methods The relevant literature for this review paper was selected by means of a search in Medline from 1970 until 1999.
results In particular the abnormalities on the antisaccade and memory saccade paradigm are remarkable. In terms of cognitive functions, poor performance on these paradigms reflects deficits in visuospatial working memory and in the inability to suppress more or less automatic responses. Both cognitive deficits can be related to dysfunction of the dorsolateral prefrontal cortex (dlpfc).
conclusions A dlpfcdefect appears to play an important role in the pathophysiology of schizophrenia. Future neuroimaging studies are likely to refine this conclusion, since they can elaborate on the knowledge of neural mechanisms. As yet, however, the value of this information is restricted because of huge methodological differences between studies.