[Topography of P300 in psychiatry--1. Cognitive P300 fields in psychoses].

P300 is known as a wave which enables the evaluation of cognitive function in neuropsychology and psychiatry. The most reliable result in psychoses was an amplitude reduction. Since similar wave alteration occurred not only in psychoses but also in dementia, the P300 reduction was too unspecific to serve as criteria for differential diagnosis. By means of topographical procedures it could be found out that the well defined P300 fields underwent characteristic changes in psychoses which even allowed a differentiation between different subgroups in schizophrenia. In hebephrenics the frontal field was very low whereas the paranoid group showed a lateralized P300-pattern with lower amplitudes in the right parieto-temporal area. In depression the P300-pattern was identical to the fields known in geriatric controls. The results will be discussed regarding other structural and functional imaging procedures. By means of topographical display of P300 the specificity of cognitive waves can be augmented considerably with the possibility to differentiate between different types of psychoses.