THE NEURAL PROCESSING AND PLASTICITY OF THE AUDITORY CORTEX EVOKED BY A RAPID TEMPORAL SEQUENCES

Speech understanding and music perception rely on the accurate detection and classification of rapid temporal sequences in the auditory input. The plosive, or stop-consonant, phonemes (e.g., “da”, ta”) forming such sequences are the classic example of auditory categorical perception. The neural processing underlying this phenomenon, however, is not completely understood. The present study focuses on this process by studying EEG responses, their plasticity (i.e., changes induced by repeated exposure), and the perception of rapid phoneme-related temporal sequences in humans. The temporal structure of the stop-consonant phonemes was modelled by rapid sequences of a short and a long noise burst (NB) separated by a short gap (Burkhard et al. 2019). EEG signals evoked by NB sequences were recorded using Ag-AgCl electrodes in a group of adult probands (n=18, age: 23-42 years) with normal hearing. Durations of the leading NB varied (5, 10, 30 ms), whereas durations of the trailing NB and gap were kept fixed (50 ms and 10 ms, respectively). The stimuli were presented and recorded using the Tucker-Davis Technologies system (TDT, Alachua, USA). The rapid NB sequences elicited distinct features in the early (0-100 ms) and late (150-500 ms) latency ranges of the EEG responses, which were modulated differently by different NB sequence parameters after repeated exposures. The present study provides novel insights into the neural processing and plasticity of the auditory system related to auditory categorical perception, potentially relevant to auditory rehabilitation of the central auditory disorders.
Supported by NextGenerationEU with RRP for SR: RESYNC 09I03-03-V04-00247.