Mismatch responses mediated by adaptation and deviance detection have complementary functional profiles that point to different auditory short-term memory systems

Mismatch negativity (MMN) is a macroscopic EEG deflection in response to rare or unexpected sounds. It has provided important insights into auditory short-term memory, pre-attentive guidance of attention, and their alteration in conditions such as schizophrenia. It remains unclear if MMN is caused by passive adaptation, active memory-comparison processes (deviance detection; DD), or a mix of both. To answer this question, macaque monkeys listened to a new paradigm that quantified both components of MMN. Micro- and macroscopic mismatch responses in the rhesus were dominated by adaptation at short latencies but included a smaller contribution of deviance detection at longer latencies. Most importantly, we show that mismatch responses mediated by adaptation have a short temporal scope and narrow frequency tuning while mismatch responses mediated by deviance detection have a longer temporal scope but broader frequency tuning. The different functional profiles point to the involvement of two distinct auditory short-term memory systems and complementary roles in the pre-attentive guidance of attention.