Master of Science
Functional Magnetic Resonance Imaging (fMRI) was used to investigate the extent, magnitude and patterns of brain activity in response to frequency-modulated sounds. We examined this by manipulating the direction (rise vs. fall) and the rate (fast vs. slow) of a series of iterated rippled noise (IRN) bursts. Participants were presented with auditory stimuli while functional images of the cortex were obtained. Univariate analyses revealed more widespread activation within auditory cortex in response to frequency-modulated sweeps compared to steady-state sounds. Furthermore, multivoxel pattern analysis (MVPA) was used to determine whether regions within auditory cortex were involved in feature-specific encoding. The pattern of activity within auditory cortex showed a high degree of consistency for the rate dimension, suggesting this pattern of activity infers representational information. Additionally, activity patterns for direction were not distinguishable, which suggests this coding occurs over a neural activity pattern not distinguishable at the level of the BOLD response.
Desouza, Diedre D., "Organization of Human Auditory Cortex: Responses to Frequency Modulated Sounds" (2013). Electronic Thesis and Dissertation Repository. 1738.