| The visual event-related potentials (ERPs) were recorded while 15 healthy participants and 8 DAT patients responded to two blocks of a Continuous Performance Test (CPT), which delivered a sequence of stimuli with varying number of matching features (from 0 to 3), a modified version by Berman, Martinez, and Noble (1993). The goals for this study were: (a) to uncover physiological markers of DAT, based on the changes in the P300 amplitudes and latencies, N200 amplitudes, and reaction times, (b) to explore group differences in the ERP response as a function of the stimulus complexity (number of matching features), and (c) to compare electrophysiological indices with cognitive competence, based on participants' performance on a battery of neuropsychological tests. As expected, the DAT group performed poorer on neuropsychological tests compared to the normal healthy group, which was further consistent with changes in the ERP pattern. The results indicated that the N200 and P300 amplitudes in response to complex stimuli (3 matching features) were considerably more pronounced and their latencies were shorter for the normal group, in comparison to the DAT group. |
