Poster Session B, Sunday, March 24, 8:00 – 10:00 am, Pacific Concourse
Rhythm violation releases auditory neural responses from adaptation
Melisa Menceloglu1, Marcia Grabowecky1, Satoru Suzuki1; 1Northwestern University
The sensory system utilizes temporal structures in the environment to build expectations about the timing of forthcoming events. Here, we investigated how neural responses adapted to auditory rhythm and reacted to stimuli that violated the rhythm. We recorded scalp EEG while 21 participants watched a nature video and passively listened to rhythmic tones with occasional temporal perturbations. In the short-interval block, tones were frequently presented (80%) with 1s inter-tone-intervals (ITIs)—fast-expected tones—and infrequently presented (20%) with 1.5s ITIs—slow-expected tones (expected because if no tone occurs at 1s, a tone is expected to occur at 1.5s with 100% probability). Conversely in the long-interval block, tones were frequently presented with 1.5s ITIs—slow-expected tones—and infrequently presented with 1s ITIs—fast-unexpected tones. We analyzed the sensory evoked EEG responses including the auditory event-related potentials (ERPs) and theta-alpha inter-trial phase coherence (ITPC) recorded from midline frontocentral sites. The results revealed an early rate-dependent adaptation (fast-expected < slow-expected, greater response attenuation for the faster rhythm), occurring within the initial 10 tones, as well as a long-term rate-independent adaptation based on the number of presented tones. Responses to the fast-unexpected tones yielded a near complete release from the early rate-dependent adaptation (fast-unexpected ~ slow-expected > fast-expected). These results suggest that (1) auditory sensory adaptation includes an early rate-dependent component and a long-term cumulative component, and (2) the early rate-dependent component may be subserved by the mechanisms that generate temporal expectations because it was nearly eliminated by the tones that violated rhythm-based expectations.
Topic Area: ATTENTION: Auditory