SEPARATE REPRESENTATION OF STIMULUS FREQUENCY, INTENSITY, AND DURATION IN AUDITORY SENSORY MEMORY - AN EVENT-RELATED POTENTIAL AND DIPOLE-MODEL ANALYSIS

The present study analyzed the neural correlates of acoustic stimulus representation in echoic sensory memory. The neural traces of auditory sensory memory were indirectly studied by using the mismatch negativi ty (MMN), an event-related potential component elicited by a change in a repetitive sound. The MMN is assumed to reflect change detection in a comparison process between the sensory input from a deviant stimulu s and the neural representation of repetitive stimuli in echoic memory . The scalp topographies of the MMNs elicited by pure tones deviating from standard tones by either frequency, intensity, or duration varied according to the type of stimulus deviance, indicating that the MMNs for different attributes originate, at least in part, from distinct ne ural populations in the auditory cortex. This result was supported by dipole-model analysis. If the MMN generator process occurs where the s timulus information is stored, these findings strongly suggest that th e frequency, intensity, and duration of acoustic stimuli have a separa te neural representation in sensory memory.