Habituation: an event-related potential and dipole source analysis study

The goal of this study was to investigate habituation processes in the brain, and in particular, to identify the brain structures involved in these processes. Therefore, event-related potentials (ERPs) were recorded in response to a series of repeated, task-irrelevant, salient stimuli presented against the background of a cognitive task which required the subjects to attend to a fixation sign on a TV screen. Stimuli were presented randomly in one of four possible quadrants of the TV screen. Dipole analyses were performed in order to localize the source of stimulus repetition effects (habituation). As expected, there was a decrease in amplitude of the N1 and P3 components as a function of stimulus repetition; habituation of N1 occurred faster than that of the P3 component. It is suggested from the results of dipole analyses that the N1 effect concerns diffuse cortical activation. The P3 habituation effect seemed to involve the temporal cortex especially.