[Cognitive impairment in Parkinson's disease--a visual event-related potential study].

The visual event-related potentials(ERPs) in Parkinson's disease(PD) are reviewed. In patients with demented PD, the task-relevant P3(P3b, target P3) latency is significantly prolonged compared with the control, while patients with nondemented PD show inconsistent results, probably due to the difference in experimental procedure or antiparkinsonian medication. The task-irrelevant P3(P3a, nontarget P3) latency under conditions of passive attention is not prolonged in PD regardless of the presence of dementia. The results of P3 amplitudes remain controversial. The N2 latency is delayed compared to the control during the semantic discrimination task, although there is no difference in NA latency. The attenuation in the CNV(contingent negative variation) amplitude is found in PD patients, probably due to the impairment, either in maintaining their attention or preparing the response.