W-17. Effects of vowel pitch and task demands on latency and amplitude of the auditory evoked M100

A recent MEG-based observation suggests that, in addition to spatial tonotopy, stimulus frequency is encoded in the latency of the auditory evoked M100: low and high frequencies generate longer latencies than midrange (1-2 kHz) frequencies. This study extends that finding to speech by demonstrating that vowel pitch correlates with latency changes. The results reveal a dissociation: vowel pitch is associated with latency shifts but not amplitude changes, task execution (categorization) is associated with amplitude increases but not latency shifts. The tone and pitch results combined suggest that there may be a further frequency coding mechanism, relying on temporal response properties of neuronal populations.