Neuropsychologic correlates of a normal EEG variant: The ... Background on Quantitative Electroencephalography

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  • NEUROPSYCHOLOGIC CORRELATES OF A NORMAL

    EEG VARIANT: THE MU RHYTHM

    Lori A. Simms, M.S.

    Dissertation Prepared for the Degree of

    DOCTOR OF PHILOSOPHY

    UNIVERSITY OF NORTH TEXAS

    August 2008

    APPROVED: Genie Bodenhamer-Davis, Chair Charles Guarnaccia, Committee Member James Hall, Committee Member Alicia Townsend, Committee Member Frank Collins, Program Coordinator Linda Marshall, Chair of the Department of

    Psychology Sandra L. Terrell, Dean of the Robert B.

    Toulouse School of Graduate Studies

  • Simms, Lori A., Neuropsychologic correlates of a normal EEG variant: The mu

    rhythm. Doctor of Philosophy (Clinical Psychology), August 2008, 86 pp., 10 tables, 7

    figures, references, 107 titles.

    Although the mu rhythm is traditionally defined as a normal EEG variant, recent

    evidence suggests that mu may have functional significance in a variety of disorders

    such as autism, Parkinson’s disease, and multiple sclerosis. While an increasing

    number of articles have focused on the blocking mechanism of mu in relation to various

    cognitive processes and disorders, few have examined the significance of a prominent

    mu rhythm in the background EEG. A few studies have examined the relationship

    between the mu rhythm and psychological disturbance, such as attentional and affective

    disorders. Increasing evidence suggests that EEG and qEEG variables may be useful in

    classifying psychiatric disorders, presenting a neurophysiological alternative to

    traditional symptom-based diagnosis and classification. Thus, the intention of the

    present study was to examine the relationship between neuropsychological variables,

    gathered from multiple assessment sources, and the presence of a prominent mu

    rhythm in the EEG. Results did not show a statistically significant difference between

    individuals with and without a prominent mu rhythm on the Test of Variables of Attention

    (TOVA); although individuals in the mu group showed a pattern of increased impulsivity

    and performance decrement over time. For adults, no significant differences were

    observed between groups on psychological variables measured by the Minnesota

    Multiphasic Personality Inventory-2 (MMPI-2). However, for children, the mu and control

    groups differed on several behavioral and emotional variables on the Child Behavior

    Checklist (CBCL). Results are examined in the context of other research and clinical

    implications are discussed.

  • Copyright 2008

    by

    Lori A. Simms

    ii

  • ACKNOWLEDGEMENTS

    First, I would like to thank my chair, Dr. Eugenia Bodenhamer-Davis for her

    mentorship, encouragement, and her influence on my growth and development as a

    young psychologist. I would like to acknowledge the late Dr. Jerry McGill, who originally

    served on my committee and provided guidance during my clinical training. In addition, I

    would like to thank Drs. James Hall and Charles Guarnaccia for agreeing to sit on my

    committee after Dr. McGill’s passing. I am grateful to Dr. Ben Morse for supporting me

    during the most challenging years of my graduate training. Finally, I wish to

    acknowledge and thank my family for their unwavering support and encouragement,

    including my parents, Anne and Mike Simms and my sister and her husband, Susanne

    and Trevor Turnbo.

    iii

  • TABLE OF CONTENTS

    Page

    ACKNOWLEDGEMENTS ............................................................................................... iii LIST OF TABLES............................................................................................................vi LIST OF FIGURES.........................................................................................................vii INTRODUCTION............................................................................................................. 1

    Objectives of the Study......................................................................................... 1 Background on Electroencephalography (EEG)................................................... 2 Background on Quantitative Electroencephalography (qEEG)............................. 3 EEG Markers for Psychological Disorders............................................................ 5 Mu Rhythm Characteristics................................................................................... 6 Physiological Mechanisms Related to Mu ............................................................ 9 Role of Mu in Cognitive Processes..................................................................... 10 Mu and Neurological Disorders .......................................................................... 11 Mu and Developmental Disorders ...................................................................... 13 Austim, Mu, and Mirror Neuron Dysfunction....................................................... 15 Mu and Psychiatric Populations.......................................................................... 18 Phenotypes and Classification of Neuropsychological Disorders ....................... 19 Mu and Phenotypes............................................................................................ 21

    RESEARCH QUESTIONS AND HYPOTHESES .......................................................... 22 METHOD....................................................................................................................... 24

    Participant Characteristics.................................................................................. 24 Instruments......................................................................................................... 25 Procedures ......................................................................................................... 34 Statistical Analyses............................................................................................. 37

    RESULTS...................................................................................................................... 40

    Testing of Assumptions ...................................................................................... 40 Preliminary Data Analyses ................................................................................. 42 Results of Primary Analyses............................................................................... 42

    iv

  • DISCUSSION ..................................................................................................... 47 Summary and Explanations of Findings ............................................................. 47 Limitations .......................................................................................................... 55 Clinical Implications ............................................................................................ 59 Recommendations for Future Research............................................................. 60

    APPENDIX: EXAMPLES OF PROMINENT MU RHYTHM............................................ 75 REFERENCES.............................................................................................................. 78

    v

  • LIST OF TABLES

    Page

    1. Demographic Characteristics of Participants ...................................................... 61

    2. Prevalence of Mu Pattern by Presenting Problem.............................................. 62

    3. Chi-square Analyses of Presenting Problems for Mu and Control Groups ......... 63

    4. One-way Analysis of Variance for MMPI-2 Scores ............................................. 64

    5. Means and Standard Deviations for MMPI-2...................................................... 65

    6. One-way Analysis of Variance for Child Behavior Checklist (CBCL) Syndrome Scales................................................................................................................. 66

    7. One-way Analysis of Variance for Child Behavior Checklist (CBCL) Broad Syndrome Scales ............................................................................................... 67

    8. Means and Standard Deviations for CBCL Variables ......................................... 68

    9. One-way Analysis of Variance for Test of Variables of Attention (TOVA)........... 69

    10. Means and Standard Deviations for TOVA Variables......................................... 70

    vi

  • vii

    LIST OF FIGURES

    Page

    1. CBCL Mean Scores, Syndrome Scales.............................................................. 71

    2. CBCL Mean Scores, Broad Syndrome Scales ................................................... 71

    3. MMPI-2 Clinical Scales, Mean Scores................................................................ 72

    4. TOVA Mean Scores............................................................................................ 72

    5. Cohen’s d Confidence Intervals, TOVA .............................................................. 73

    6. Cohen’s d Confidence Intervals, CBCL .............................................................. 73

    7. Cohen’s d Confidence Intervals, MMPI-2 ........................................................... 74

  • INTRODUCTION

    Objectives of