SELECTIVE ATTENTION ENHANCES THE AUDITORY 40-HZ TRANSIENT-RESPONSE INHUMANS

STUDIES of human auditory1-3 and somatosensory3 modalities have shown that there is an oscillatory response in the gamma-band (at about 40 H z) frequency which is elicited by either steady state1-3 or transient4 stimulation. The auditory 40-Hz response is generated at least partia lly in the auditory cortex4,5 as a result of thalamocortical interacti on6 and may serve perceptual integration7,8 and conscious perception9. A connection to selective attention has been implied in human10 and a nimal11 studies, although the evidence is inconclusive12. Moreover, fu ndamental differences between the human and animal 40-Hz responses13 p rohibit generalization. Furthermore, most experiments have used steady -state stimulation during which the brain does not regain its resting state between stimuli as it does when transient stimulation is used14. Here we study the effect of selective attention on the auditory gamma -band (40-Hz) transient response using subjects listening to tone pips presented in one ear while ignoring a concurrent sequence of tone pip s in the other ear. The 40-Hz response was larger when subjects paid a ttention to stimuli rather than ignored them. This attention effect wa s most pronounced over the frontal and central scalp areas. Our result s demonstrate a physiological correlate of selective attention in the 40-Hz transient response in humans.