THE TRANSIENT 40-HZ RESPONSE, MISMATCH NEGATIVITY, AND ATTENTIONAL PROCESSES IN HUMANS

1. Recent experimental studies on the neurophysiological basis of audi tory selective attention and sensory memory forming the sensory-data b asis for tuning the selective-attention system in humans are reviewed. 2. The results demonstrate that the transient 40-Hz response is enhan ced by selective attention, attenuated in the course of long-term stim ulation, but is not affected by changes in auditory stimuli. 3. Theref ore, the 40-Hz response seems to be closely related to selective and s ustained attention, whereas it does not seem to be associated with pas sive attention, as it does not reflect the detection of changes in aud itory stimuli. 4. Changes in auditory stimulation are registered by pr e-attentive sensory memory, indexed by the mismatch negativity (MMN), a change-specific component of the event-related potentials (ERPs), By this time, the transient 40-Hz response has already terminated, The m agnitude of stimulus change is reflected in MMN latency. These latency changes predict changes in attentive reaction time (RT). 5. Thus, the pre-attentive memory mechanism seems to govern attentive detection of changes in the auditory environment. 6. It is concluded that the tran sient 40-Hz response is related to active attention and MMN is related to passive attention.