CALIFORNIA STATE UNIVERSITY, NORTHRIDGE

AGE-RELATED DIFFERENCES IN BRAIN ACTIVATION

A thesis submitted in partial fulfillment of the requirements for

The degree of Master of Arts in Community / Clinical

by

Craig A. Goodman

August 1998

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The Thesis of Craig Goodman is approved:

__________________________________ ________________

Sheila K. Grant-Thompson, Ph.D. Date

__________________________________ ________________

Carrie Saetermoe. Ph.D. Date

__________________________________ ________________

Maura Mitrushina, Ph.D., Chair Date

California State University, Northridge

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Acknowledgement

I wish to extend my gratitude to the following people who have made this project a

rewarding and enriching experience. To my comrades in the laboratory; Kenneth

Thomas, M.A., Denise Torgerson, B.A., and Renee Galbavy, B.A., thank you for all your

help in data acquisition, and training. Special thanks are due to Dr. Steven Berman

whose invaluable knowledge and guidance made this thesis possible. Especially to my

mentor, Dr. Maura Mitrushina, who has been a source of inspiration and unfailing belief

in my efforts, providing so many keys that have unlocked the doors to my future.

Finally, to my wife Hagit, all your love and support has helped me overcome the

challenges and obstacles, and made my dreams a reality.

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TABLE OF CONTENTS

Page

Signature Page ii

Acknowledgement iii

Abstract viii

Introduction 1

Methods of Investigation of Brain Functioning 1

Evoked Potentials 1

Nomenclature 3

P300 Waveform 4

N200 Waveform 7

Recording of Electrical Potentials from the Scalp 7

Artifacts 8

Measurement and Analysis of ERPs 11

Clinical Applications 13

Utility of Electrophysiological Measures in the Study

of Age-Related Cognitive Decline 15

. Cognitive Decline in the Elderly 15

Evoked Potentials in the Elderly 18

Method 23

Participants 23

Apparatus and Procedure 23

Data Analysis 25

Results 27

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P3 27

P3 Amplitude 27

P3 Latency 30

N2 31

N2 Amplitude 31

N2 Latency 34

Reaction Time 36

Correct Responses 36

Correlations 37

Discussion 40

References 45

Tables

1. Between and Within Groups Analysis of Variance 55

2. P3 Amplitude and Latency as a Function of

Number of Matching features and age 56

3. N2 Amplitude as a function of Electrode and Age 57

4. Correlations Between P3 Amplitude and N2

Amplitude 58

5. Correlations Between P3 Latency and N2 Latency 59

6. Correlations Between P3 Amplitude and P3

Latency 60

7. Correlations Between N2 Amplitude and N2

Latency 61

8. Correlations Between RT and P3 62

9. Correlations Between RT and N2 63

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Figure Caption 64

Figure 1.a) P3 Analysis for N-Task with Zero Matching

Features 65

b) P3 Analysis for Z-Task with Zero Matching

Features 66

c) P3 Analysis for N-Task with One Matching

Feature 67

d) P3 Analysis for Z-Task with One Matching

Feature 68

e) P3 Analysis for N-Task with Two Matching

Features 69

f) P3 Analysis for Z-Task with Two Matching

Features 70

g) P3 Analysis for N-Task with Three Matching

Features 71

h) P3 Analysis for Z-Task with Three Matching

Features 72

Figure 2.a) N2 Analysis for N-Task with One Matching

Feature 73

b) N2 Analysis for Z-Task with One Matching

Feature 74

c) N2 Analysis for N-Task with Two Matching

Features 75

d) N2 Analysis for Z-Task with Two Matching

Features 76

e) N2 Analysis for N-Task with Three Matching

Features 77

f) N2 Analysis for Z-Task with Three

Matching Features 78

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Figure 3.a) N2 Amplitudes for Electrodes in Young

and Elderly 79

b) N2 Latency for Electrodes in Young and

Elderly 80

Appendix

International 10 – 20 System of Electrode

Placement 81

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ABSTRACT

AGE-RELATED DIFFERENCES IN BRAIN ACTIVATION

by

Craig A. Goodman

Master of Arts in Community / Clinical

The research presented relates to the field of cognitive and electrophysiological

differences between the young and elderly adults. Event-related potentials (ERPs) were

recorded from young adults (N = 24, age 18-34) and elderly (N = 15, age 60-80) in

response to two continuous performance tasks varying in complexity. The elderly group

demonstrated significantly longer latencies for both P3 and N2 components of ERPs.

Higher amplitudes for both N2 and P3 components were found to be associated with

increasing complexity of cognitive demands for the young group, but not for the elderly

group. This reflects an age-related decline in the ability to effectively evaluate the

complex stimuli. Age group differences were also found in scalp topography for N2

amplitude, with the young group demonstrating a more posterior distribution, while the

elderly group had a more anterior shift in distribution. Results indicated that the elderly

demonstrated less elaborative controlled strategic processing for the more

psychomotorically complex tasks. In evaluating reaction times and latencies of both N2

and P3 components for both tasks, the elderly showed longer processing times,

suggesting increased mental slowing associated with advancing age. Findings are

consistent with the literature on age-related cognitive decline.