MEASURING PHONOLOGICAL PROCESSING AND PHONOLOGICAL WORKING MEMORY IN ADULTS WITH DEVELOPMENTAL DYSLEXIA: A FUNCTIONAL MAGNETIC RESONANCE IMAGING STUDY By TIMOTHY W. CONWAY A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2003 Copyright 2003 by Timothy Wayne Conway This dissertation is dedicated to my parents, Walter and Julie Conway, who have always provided me with unconditional support and love, as well as modeled an insatiable desire to learn, and a compassion for others. ACKNOWLEDGMENTS I would like to acknowledge my wife (Amy) and children (Sheridan and Chloe), immediate family, and friends for their tireless support. I would especially like to acknowledge Dr. Bruce Crosson for showing remarkable patience with me during this unexpectedly lengthy process, as well as Dr. Ken Heilman for the encouragement to pursue a doctoral degree by seeing “a racehorse pulling a cart.” I extend sincere gratitude to my committee members for their support and guidance. I extend special thanks to Kaundinya Gopinath, Kyung Peck, Harris Slepian, Leslie Gonzalez-Rothi, Debbie Moncrieff, Tom Chesnes, Ann Alexander, Leeza Maron, and Stacey Hoffman for assistance with many aspects of this scholarly endeavor. The faculty and staff of the University of Florida's Department of Clinical and Health Psychology provided the remarkable education and training that were necessary for conceptualizing and completing this research project. Outstanding technical assistance was provided by the staff of the CIRCA Electronic Thesis and Dissertation Laboratory. Financial assistance for this research was graciously provided by the Donald D. Hammill Foundation, American Psychological Foundation, Patricia C. Lindamood, the Fred J. Wellington Foundation, and Grant HD 30988 awarded to Joseph K. Torgesen by the National Institute of Child Health and Human Development. iv TABLE OF CONTENTS Page ACKNOWLEDGMENTS ................................................................................................. iv LIST OF TABLES............................................................................................................ vii LIST OF FIGURES ........................................................................................................... ix LIST OF OBJECTS.............................................................................................................x ABSTRACT....................................................................................................................... xi CHAPTER 1 INTRODUCTION........................................................................................................1 2 PHONOLOGICAL PROCESSING..............................................................................7 3 MODELS OF READING...........................................................................................12 4 FUNCTIONAL NEUROIMAGING ..........................................................................26 Methodological Considerations of Functional Neuroimaging ...................................28 PET Neuroimaging of Pure Tone and Phonological Stimuli......................................29 Pure Tone Stimulus .............................................................................................29 Phonological Stimulus.........................................................................................32 FMRI of Pure Tone and Phonological Stimuli...........................................................34 Pure Tone Stimulus .............................................................................................35 Phonological Stimulus ........................................................................................36 5 RATIONALE AND HYPOTHESES .........................................................................38 Statement of the Problem............................................................................................38 Hypotheses for Experiment One-Counting and Segmenting......................................40 Hypothesis 1–Tone Counting..............................................................................40 Hypothesis 2–Phoneme Counting .......................................................................41 Hypothesis 3–Pseudoword Segmenting ..............................................................42 Hypotheses for Experiment Two–Working Memory Comparisons...........................43 Hypothesis 1–Tone Comparison .........................................................................43 Hypothesis 2–Pseudoword Comparison..............................................................44 v 6 METHODS.................................................................................................................45 Participants and Selection Criterion ...........................................................................45 Apparatus and Scanning Procedures ..........................................................................49 Stimulus Parameters ...................................................................................................53 Experiment One-Counting and Segmenting........................................................55 Tone counting...............................................................................................57 Phoneme counting........................................................................................57 Pseudoword segmenting...............................................................................58 Experiment Two–Working Memory Comparisons.............................................58 Tone comparison..........................................................................................60 Pseudoword comparison ..............................................................................60 Functional Neuroimage Analysis ...............................................................................61 7 RESULTS...................................................................................................................64 Behavioral Results......................................................................................................64 FMRI Results..............................................................................................................69 Experiment One–Tone and Phoneme Counting, and Pseudoword Segmenting .69 Temporal region ...........................................................................................71 Frontal region ...............................................................................................73 Parietal region. .............................................................................................74 Experiment Two-Tone Comparison and Pseudoword Comparison....................74 Tone comparison..........................................................................................76 Pseudoword comparison versus baseline white Noise.................................81 8 DISCUSSION.............................................................................................................87 APPENDIX A. NEUROPSYCHOLOGICAL ASSESSMENT.........................................................106 B. EXPERIMENT ONE–EXPLORATORY ANALYSIS............................................108 LIST OF REFERENCES.................................................................................................113 BIOGRAPHICAL SKETCH ...........................................................................................124 vi LIST OF TABLES Table page 5-1 Experiment One–Tasks and Hypothesized Regions of Activity per Group.............43 5-2 Experiment Two–Tasks and Hypothesized Regions of Activity per Group............44 6-1 Matching Variables for Control and Dyslexic Groups.............................................46 6-2 Demographic Data per Group. .................................................................................46 6-3 Variables for Defining Group Membership .............................................................49 6-4 Counting and Segmenting Task Descriptions ..........................................................56 6-5 Counting and Segmenting Cognitive Components per Tasks..................................57 6-6 Working Memory Comparison Description of Tasks..............................................59 6-7 Working Memory Comparison Cognitive Components per Task. ..........................59 7-1 State and Trait Anxiety Levels Prior to FMRI.........................................................64 7-2 Reading skills per Group..........................................................................................65 7-3 Part 1 Phonological Processing Abilities per Group................................................66 7-4 Part 2 Phonological Processing Abilities per Group................................................66 7-5 Auditory Working Memory and Attention Abilities per Group ..............................66 7-6 Rapid Naming Abilities per Group. .........................................................................67 7-7 Experiment One Response Accuracy per Group......................................................67 7-8 Experiment Two Response Accuracy per Group.....................................................68 7-9 Active Temporal Regions from Within-groups Analyses........................................72 7-10 Temporal Region Activity per Group for Tone Comparison versus