INTERACTION BETWEEN REPRESENTATIONS OF DIFFERENT FEATURES OF AUDITORYSENSORY MEMORY

THE neurophysiological basis of sensory memory was studied by measurin g the magnetic counterpart (MMNm) of the mismatch negativity (MMN) wit h a whole-head 122-channel magnetometer. The MMNm is a response to a d ifference in the presented stimulus and a neuronal memory trace formed by repeated standard stimuli. This trace must contain information abo ut the feature differing in the deviant. Keeping one feature (frequenc y) constant, we studied how other stimulus features affect the strengt h of the MMNm. The MMNm to a frequency change was weaker when the othe r features varied than when they were constant. This suggests that the MMNm to a frequency change is not independent of other stimulus featu res.