Persisting versus sustained neural activity: effects on transient N100m response

Previous evidence from animal and human studies suggests that neural activity, both during a continuous tone and persisting after the offset of a first tone, can prolong the latency and enhance the amplitude of a transient response to a second tone. Our results showed that the latency of N100m to a second tone presented to the opposite ear was prolonged equally in both conditions. Unexpectedly, the effects on response strength strongly depended on stimulus laterality: the ipsilateral but not the contralateral N100m to the second tone was enhanced by the simultaneous presence of the first when compared with the effect of the preceding tone. This suggests that sustained neural activity during a continuous tone can release inhibition normally induced by ipsilateral stimulation.