BME PhD Defense Announcement for Ravinderjit Singh

Title: Auditory tracking and scene analysis - perceptual timescales and neural correlates

Time: Feb 28 11:00 am -- Zoom 

Advisory Committee:

Dr. Hari M. Bharadwaj, Advisor

Dr. Michael G. Heinz

Dr. Gregory Francis

Dr. Edward L. Bartlett

Abstract:

Temporal processing and temporal coherence processing are fundamental components of auditory processing and the focus of the work in this thesis. Cortical temporal processing is understudied in humans. This dissertation makes three contributions that help characterize auditory temporal processing, and its relationship to auditory perception in humans. Experiment 1 develops a novel systems identification approach utilizing modified maximum length sequences (m-seq) to robustly measure cortical temporal processing noninvasively. Using this technique, it is found that cortex's ability to track dynamic spatial auditory cues can explain ability to utilize dynamic binaural information to do a spatial unmasking task. This result combined with behavioral data demonstrating FM tracking extends out to similar rates as spatial tracking demonstrates how auditory tracking broadly is constrained by the temporal properties of late areas of cortex. Experiment 2 develops a novel measure of temporal processing, called the modulation temporal response function (mod-TRF), which can separate the underlying sources contributing to modulation processing along the auditory system from short, middle, and late latency regions. The mod-TRF has a robust SNR at the individual level giving it the potential to become a ubiquitous tool to assess temporal processing and auditory activity generally across individuals. The utility of the mod-TRF is demonstrated by evaluating how attention affects different sources along the auditory pathway differently. Other studies utilizing the mod-TRF could explore how temporal processing in early and late areas of the auditory system changes with aging, hearing loss, musicianship, and neuropsychiatric disorders. Experiment 3 establishes a novel physiological measure of across channel temporal coherence processing to measure auditory binding ability across individuals. It is demonstrated how this novel temporal coherence measure can explain performance at a behavioral temporal coherence detection task, speech-in-noise task, and comodulation masking release. Lastly, it is explored how social and communicative features in individuals, measured via the Autism Quotient, align with differences in auditory ability in various tasks.