The formation of echoic memory traces has traditionally been inferred from the enhanced responses to its
deviations. The mismatch negativity (MMN), an auditory event-related potential (ERP) elicited between 100
and 250 ms after sound deviation is an indirect index of regularity encoding that reflects a memory-based
comparison process. Recently, repetition positivity (RP) has been described as a candidate ERP correlate of direct
memory trace formation. RP consists of repetition suppression and enhancement effects occurring in different
auditory components between 50 and 250 ms after sound onset. However, the neuronal generators engaged in