Auditory processes on different temporal scales revealed by cortical oscillation Xiangbin Teng Poeppel Lab Psychology Department New York University

Vision :How does the auditory system extract features from sounds? Audition Water frequency frequency Multiple filters Two filters Cortical responses entrained by sounds TimeTime 3 kinds of sound; 90 trials Procedure 2 s Time One trial Continuous MEG recoding Baseline 1 1.5 s Which Sound? Three stimuli Three timescales Theta band 4 7 Hz Alpha band 8 12 Hz Gamma band 30 45 Hz 27100190Duration(ms) 2000 500 1000 1500 2000 500 1000 1500 2000 500 1000 1500 0 .5 1 1.5 2 Time (s) frequency(Hz) b)a) ~27 ms ~100 ms ~190 ms sound sound sound 2 10 19

Inter-trial phase coherence sound sound sound Z Score of ITC ** * ** * * theta alpha beta gamma 10 20 30 40 50 Frequency (Hz) 4-7 Hz 8-12 Hz 13-30 Hz 31-45 Hz Zscore -.5 .5 1.5 2.5 3.5 2 Zscore -.5 .5 1.5 2.5 3.5 theta alpha beta gamma .17 .25 .17 .22 .17 .20 .17 .20 sound sound sound Topography of Inter-trial phase coherence Decoded Label StimulusLabel Phase Decoding Power Decoding Decoded Label .42 .30 Confusion Matrix Percentage Decoding performance using phase and power Detailed decoding procedure can be seen in Ng, Logothetis, and Kayser, 2013 sound sound sound Phase decoding Power decoding .3 .2 .1 0 d *** *** *** *** ** .25 .20 .15 .10 d .05 N N N NY Y Y Y theta alpha beta gamma Effects of Frequency Band on Phase Decoding

Summary Phase of cortical oscillations, not power, encodes acoustic dynamics. Cortical oscillations at theta and gamma bands track acoustic dynamics, and contribute to decoding of all stimuli. Cortical oscillation at alpha band can not be entrained by stimulus with corresponding modulation rate. Beta frequency band did not provide information for decoding different stimuli. The auditory system mainly uses theta and gamma bands to sample and represent sound, which supports a two-timescale processing strategy.

Thank you

Single-trial Classification Trial 1 e.g. sound (25 trials) Trial 2 Trial 24 Trial 25 Phase Template Power Template

Phase Template of Circular distance Phase Template of Phase Template of The smallest distance Label: l2 distance Label:

Without theta band With theta band Contribution of each band to decoding different sounds