Temporal integration: reflections in the M100 of the auditory evoked field.

Previous work investigating temporal integration in the formation of the auditory evoked field component, M100, indicates an accumulation of stimulus attribute information in the processes underlying the M100 response with a temporal window for this integration of approximately 25-32 ms. We investigate the influence of stimulus duration on M100 amplitude using sinusoidal tone stimuli of increasing duration under two experimental conditions: constant intensity, and constant energy (with stimulus intensity decreasing as duration increased). We report that M100 amplitude increases with stimulus duration up to a point of saturation at approximately 40 ms; importantly, this dependence holds in both experimental conditions, despite differing stimulus intensities. Thus we conclude that (within this approximately 40 ms temporal window) stimulus duration itself, and not integrated energy, determines M100 amplitude.