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dc.contributor.advisorSydney S. Cash.en_US
dc.contributor.authorDykstra, Andrew R. (Andrew Richard)en_US
dc.contributor.otherHarvard University--MIT Division of Health Sciences and Technology.en_US
dc.date.accessioned2012-01-12T19:28:46Z
dc.date.available2012-01-12T19:28:46Z
dc.date.issued2011en_US
dc.identifier.urihttp://hdl.handle.net/1721.1/68451
dc.descriptionThesis (Ph. D.)--Harvard-MIT Division of Health Sciences and Technology, September 2011.en_US
dc.description"August, 2011." Vita. Cataloged from PDF version of thesis.en_US
dc.descriptionIncludes bibliographical references.en_US
dc.description.abstractOne of the primary functions of the human auditory system is to separate the complex mixture of sound arriving at the ears into neural representations of individual sound sources. This function is thought to be crucial for survival and communication in noisy settings, and allows listeners to selectively and dynamically attend to a sound source of interest while suppressing irrelevant information. How the brain works to perceptually organize the acoustic environment remains unclear despite the multitude of recent studies utilizing microelectrode recordings in experimental animals or non-invasive human neuroimaging. In particular, the role that brain areas outside the auditory cortex might play is, comparatively, vastly understudied. The experiments described in this thesis combined classic behavioral paradigms with electrical recordings made directly from the cortical surface of neurosurgical patients undergoing clinically-indicated invasive monitoring for localization of epileptogenic foci. By sampling from widespread brain areas with high temporal resolution while participants simultaneously engaged in streaming and jittered multi-tone masking paradigms, the present experiments sought to overcome limitations inherent in previous work, namely sampling extent, resolution in time and space, and direct knowledge of the perceptual experience of the listener. In experiment 1, participants listened to sequences of tones alternating in frequency (i.e., ABA-) and indicated whether they perceived the tones as grouped ("1 stream") or segregated ("2 streams"). As has been reported in neurologically-normal listeners since the 1950s, patients heard the sequences as grouped when the frequency separation between the A and B tones was small and segregated when it was large. Evoked potentials from widespread brain areas showed amplitude correlations with frequency separation but surprisingly did not differ based solely on perceptual organization in the absence of changes in the stimuli. In experiment 2, participants listened to sequences of jittered multi-tone masking stimuli on which a regularly-repeating target stream of tones was sometimes superimposed and indicated when they heard the target stream. Target detectability, as indexed behaviorally, increased throughout the course of each sequence. Evoked potentials and high-gamma activity differed strongly based on the listener's subjective perception of the target tones. These results extend and constrain theories of how the brain subserves auditory perceptual organization and suggests several new avenues of research for understanding the neural mechanisms underlying this critical function.en_US
dc.description.statementofresponsibilityby Andrew R. Dykstra.en_US
dc.format.extent181 p.en_US
dc.language.isoengen_US
dc.publisherMassachusetts Institute of Technologyen_US
dc.rightsM.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.en_US
dc.rights.urihttp://dspace.mit.edu/handle/1721.1/7582en_US
dc.subjectHarvard University--MIT Division of Health Sciences and Technology.en_US
dc.titleNeural correlates of auditory perceptual organization measured with direct cortical recordings in humansen_US
dc.typeThesisen_US
dc.description.degreePh.D.en_US
dc.contributor.departmentHarvard University--MIT Division of Health Sciences and Technology.en_US
dc.identifier.oclc769119404en_US


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