Title page for ETD etd-06072006-124145
|Type of Document
||Alden, John Dale
||Hemispheric reactivity to bright light exposure : a test of the relationship between age, hemi-activation and depression
|Harrison, David W.
|Lanter, James J.
|Prestrude, Albert M.
|Stephens, Robert S.
|Winett, Richard A.
- Cerebral hemispheres
- Brain Aging
|Date of Defense
Much of the research on differential hemispheric activation as a function of age
or the presence of depression suggests that a relative decrease in left hemisphere
activation is associated with depression, while a decrease of right hemisphere
activation is associated with age. Recent research, however, has demonstrated
the role of the right hemisphere in maintaining general behavioral arousal. Pilot
data suggest that elderly people experience behavioral over-arousal when
presented with stressful or novel environmental stimuli. Equally interesting is the
finding in a single-case study that ambient light and noise have a differential
effect on behavior presumed to be representative of the left and the right cerebral
hemispheres. The left hemisphere appears to be more responsive to ambient light
level, with the right hemisphere being more responsive to ambient noise level.
The present study sought to provide further support of selective hemispheric
activation to bright light, and to examine the relationships among hemi-activation,
age and depression by using behavioral measures of lateral anterior (finger
tapping rate) and posterior (dichotic listening) cortical functioning. Two
identical experiments were employed to evaluate old and young, and depressed
and non-depressed sUbjects. Direct evidence of right herni-aging effects on
laterality was not significant in the first experiment, but data suggested the
possibility of a ceiling effect for behavioral arousal in the older group which was
not seen in younger subjects. The second experiment yielded no significant
results between depressed and non-depressed groups. Hypotheses of under and
over arousal in subjects are proposed to explain findings. Possible implications
for treatment and recommendations for further research are proposed.
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