Selective attention enhances the auditory 40-Hz transient response in humans

Abstract

STUDIES of human auditory^1–3 and somatosensory³ modalities have shown that there is an oscillatory response in the γ-band (at about 40 Hz) frequency which is elicited by either steady state^1–3 or transient⁴ stimulation. The auditory 40-Hz response is generated at least partially in the auditory cortex^4,5as a result of thalamocortical interaction⁶ and may serve perceptual integration^7,8 and conscious perception⁹. A connection to selective attention has been implied in human¹⁰ and animal¹¹ studies, although the evidence is inconclusive¹². Moreover, fundamental differences between the human and animal 40-Hz responses¹³ prohibit 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 γ-band (40-Hz) transient response using subjects listening to tone pips presented in one ear while ignoring a concurrent sequence of tone pips in the other ear. The 40-Hz response was larger when subjects paid attention to stimuli rather than ignored them. This attention effect was most pronounced over the frontal and central scalp areas. Our results demonstrate a physiological correlate of selective attention in the 40-Hz transient response in humans.