Cross-Modal Repetition Effects on the N4

Abstract

Event related brain potentials (ERP) were recorded from 12 normal right-handed subjects from 13 midline and lateral scalp sites during a task that involved learning a list of 20 words in the auditory modality, followed by recognition memory testing in first the auditory and then the visual modality. Subjects were instructed to keypress to repeated words, which were randomly mixed with an equal number of novel distractor words. A decrement in the amplitude of the N4 component of ERPs and an increase in the P3 component was found following repeated words in the auditory condition, and this difference persisted across modalities to the visual condition, although the anterior-posterior distribution of the N4 difference changed between conditions. The cross-modal transfer of the repetition-induced N4 attenuation suggests that the N4 change may be modulated by a semantic (i.e., non-modality specific) memory trace, while the difference in its distribution between the auditory and visual conditions provides evidence for a modality-specific contribution to the N4 generator.