Sensorimotor Modulations by Cognitive Processes During Accurate Speech Discrimination: an EEG Investigation of Dorsal Stream Processing David E
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University of Tennessee Health Science Center UTHSC Digital Commons Theses and Dissertations (ETD) College of Graduate Health Sciences 5-2018 Sensorimotor Modulations by Cognitive Processes During Accurate Speech Discrimination: An EEG Investigation of Dorsal Stream Processing David E. Jenson University of Tennessee Health Science Center Follow this and additional works at: https://dc.uthsc.edu/dissertations Part of the Speech and Hearing Science Commons, and the Speech Pathology and Audiology Commons Recommended Citation Jenson, David E. (http://orcid.org/https://orcid.org/0000-0002-1007-8579), "Sensorimotor Modulations by Cognitive Processes During Accurate Speech Discrimination: An EEG Investigation of Dorsal Stream Processing" (2018). Theses and Dissertations (ETD). Paper 455. http://dx.doi.org/10.21007/etd.cghs.2018.0449. This Dissertation is brought to you for free and open access by the College of Graduate Health Sciences at UTHSC Digital Commons. It has been accepted for inclusion in Theses and Dissertations (ETD) by an authorized administrator of UTHSC Digital Commons. For more information, please contact [email protected]. Sensorimotor Modulations by Cognitive Processes During Accurate Speech Discrimination: An EEG Investigation of Dorsal Stream Processing Document Type Dissertation Degree Name Doctor of Philosophy (PhD) Program Speech and Hearing Science Track Speech and Language Pathology Research Advisor Tim Saltuklaroglu, Ph.D. Committee Andrew L. Bowers, Ph.D. Devin Casenhiser, Ph.D. Ashley W. Harkrider, Ph.D. Kevin J. Reilly, Ph.D. ORCID http://orcid.org/https://orcid.org/0000-0002-1007-8579 DOI 10.21007/etd.cghs.2018.0449 This dissertation is available at UTHSC Digital Commons: https://dc.uthsc.edu/dissertations/455 Sensorimotor Modulations by Cognitive Processes During Accurate Speech Discrimination: An EEG Investigation of Dorsal Stream Processing A Dissertation Presented for The Graduate Studies Council The University of Tennessee Health Science Center In Partial Fulfillment Of the Requirements for the Degree Doctor of Philosophy From The University of Tennessee By David E. Jenson May 2018 Copyright © 2018 by David E. Jenson. All rights reserved. ii DEDICATION This dissertation is dedicated to my wife Allison and my daughters Norah, Callie, and Eve. Thank you for your love, encouragement, and support. You have sustained me through this process, and I would not have been able to do this without you. iii ACKNOWLEDGEMENTS I would like to thank Dr. Tim Saltuklaroglu for his mentorship and guidance. I appreciate the time and effort that he has invested in both my academic and personal development. I am grateful for the deft hand that he has displayed as he has nurtured me towards academic independence. I would like to thank my committee members, Dr. Ashley W. Harkrider, Dr. Devin Casenhiser, Dr. Kevin J. Reilly, and Dr. Andrew L. Bowers for their support and guidance during my doctoral training. I have appreciated their advice, critiques, and thoughtful questions that have shaped the development of this manuscript. I would like to thank David Thornton for being a steady compatriot and invaluable resource through this process. He has given up countless hours to assist me with data collection, brainstorming sessions, manuscript review, and other tasks that brought him no direct benefit. I am grateful for the camaraderie and support, which have provided much needed levity along the way. I would like to thank the Graduate College at the University of Tennessee Health Science Center for providing financial support towards my completion of the Ph.D. program. I would like to acknowledge Blake Rafferty for his assistance with data collection for this project. And a final thank you to my parents. Thank you for championing curiosity and instilling a love of puzzles when I was young. iv ABSTRACT Internal models mediate the transmission of information between anterior and posterior regions of the dorsal stream in support of speech perception, though it remains unclear how this mechanism responds to cognitive processes in service of task demands. The purpose of the current study was to identify the influences of attention and working memory on sensorimotor activity across the dorsal stream during speech discrimination, with set size and signal clarity employed to modulate stimulus predictability and the time course of increased task demands, respectively. Independent Component Analysis of 64– channel EEG data identified bilateral sensorimotor mu and auditory alpha components from a cohort of 42 participants, indexing activity from anterior (mu) and posterior (auditory) aspects of the dorsal stream. Time frequency (ERSP) analysis evaluated task- related changes in focal activation patterns with phase coherence measures employed to track patterns of information flow across the dorsal stream. ERSP decomposition of mu clusters revealed event-related desynchronization (ERD) in beta and alpha bands, which were interpreted as evidence of forward (beta) and inverse (alpha) internal modeling across the time course of perception events. Stronger pre-stimulus mu alpha ERD in small set discrimination tasks was interpreted as more efficient attentional allocation due to the reduced sensory search space enabled by predictable stimuli. Mu-alpha and mu- beta ERD in peri- and post-stimulus periods were interpreted within the framework of Analysis by Synthesis as evidence of working memory activity for stimulus processing and maintenance, with weaker activity in degraded conditions suggesting that covert rehearsal mechanisms are sensitive to the quality of the stimulus being retained in working memory. Similar ERSP patterns across conditions despite the differences in stimulus predictability and clarity, suggest that subjects may have adapted to tasks. In light of this, future studies of sensorimotor processing should consider the ecological validity of the tasks employed, as well as the larger cognitive environment in which tasks are performed. The absence of interpretable patterns of mu-auditory coherence modulation across the time course of speech discrimination highlights the need for more sensitive analyses to probe dorsal stream connectivity. v TABLE OF CONTENTS CHAPTER 1. INTRODUCTION .....................................................................................1 CHAPTER 2. LITERATURE REVIEW .........................................................................7 The Dorsal Stream ...........................................................................................................7 Necessity of Considering Cognitive Processes in Speech Perception .............................7 Attentional Modulation of Dorsal Stream Activity in Speech Perception .....................10 Predictive Coding Contributions to Attention ...........................................................10 Inhibitory Contributions to Attention ........................................................................13 Working Memory Contributions to Dorsal Stream Activity in Speech Perception ......15 Electroencephalography and the Mu Rhythm ...............................................................17 Mu Alpha ...................................................................................................................18 Mu Beta ......................................................................................................................19 Internal Modeling in Speech Perception ........................................................................22 Pre-stimulus Beta and Predictability ..........................................................................23 Early Alpha ERS and Inhibitory Control ...................................................................25 Late Mu Activity and Covert Rehearsal ....................................................................27 Auditory Alpha as an Index of Posterior Dorsal Stream Activity .................................30 Connectivity Across the Dorsal Stream in Speech Perception ......................................33 CHAPTER 3. METHODOLOGY ..................................................................................36 Participants .....................................................................................................................36 Stimuli ............................................................................................................................36 Design ............................................................................................................................37 Procedures ......................................................................................................................37 Neural Data Acquisition ................................................................................................38 Data Processing ..............................................................................................................40 Pre-processing ............................................................................................................40 Independent Component Analysis .............................................................................41 Dipole Localization ....................................................................................................41 Study Module .............................................................................................................41 PCA Clustering ..........................................................................................................42