THE PERCEPTION OF TEMPORAL STRUCTURE AND AUDITORY-EVOKED BRAIN ACTIVITY

The processing and perception of auditory signals depends on the tempo ral structure of stimulus characteristics. We studied 26 healthy subje cts who participated in psychophysical experiments and in electrophysi ological recordings of auditory evoked potentials from C-2, C-3, C-4, T-3 and T-4. Stimuli consisted of tone series presented binaurally as tones or gaps with a base duration of 100 ms. In the psychophysical ex periments, difference thresholds as indicators of temporal discriminat ion performance were significantly lower for tones than for gaps. In t he electrophysiological recordings, gaps often failed to elicit N100 c omponents. Tones produced shortest component latencies with largest am plitudes. In addition, brain activity was strongest at C-2, and showed a symmetrical fall-off over both hemispheres. N100 components had sig nificantly longer latencies and smaller amplitudes when they were evok ed by the end of the gap (i.e. with the continuation of the tone) than by tones.-Our data illustrate how the temporal structure of auditory stimuli affects neuronal responses of the brain. Similar effects were observed in psychophysical and electrophysiological experiments, and w e were able to demonstrate a direct relationship between subjective se nsory thresholds and auditory evoked brain activity.