Electrophysiological indices of spatial processing in the mature and developing human auditory system
Abstract
The ability to localize sounds in space is fundamental to interacting with our environment. Mechanisms for sound localization are complex, and involve many stages of processing. Much work has been done using behavioural measures in humans, and electrophysiological studies in animal models, but the neural processes underlying sound localization remain unclear. Recent work has turned to functional imaging techniques such as functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) which allow us to better address questions such as the extent to which sound localization is an automatic process, the stages of processing for sound location, and how sound localization abilities develop. ^ In Chapter 2, we examined the effects of spatial separation and stimulus probability on auditory event-related potentials (ERPs). We found that the difference waves elicited by standard and deviant stimuli showed a biphasic response generated in secondary auditory cortex with negative and positive peaks around 125 and 226 ms respectively after deviant onset. This response resulted from the automatic detection of contextual changes, rather than changes in simple acoustic features. ^ Chapter 3 investigated whether context-dependent responses elicited by occasional changes in sound location could be measured in primary auditory cortex. We found significant enhanced negativities in the event-related potentials elicited by deviant stimuli as early as 25 ms after stimulus onset, in addition to the differences around 125 ms which were reported in Chapter 2. ^ Chapter 4 investigated the development of auditory event-related potentials elicited by occasional changes in location in early infancy. Using a similar paradigm to that used in Chapter 2, we found enhanced slow, positive responses to deviant stimuli across all ages tested between 1 and 8 months of age. We also found a faster, negative response to deviant stimuli in some 6- and 8-month-old infants, although there was much variability in this response across infants. ^
Subject Area
Psychology, Experimental
Recommended Citation
Ranil Sonnadara,
"Electrophysiological indices of spatial processing in the mature and developing human auditory system"
(January 1, 2006).
ETD Collection for McMaster University.
Paper AAINR20410.
http://digitalcommons.mcmaster.ca/dissertations/AAINR20410
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