Neurophysiological correlates of age-related changes in human motor function.
BACKGROUND
There are well-defined and characteristic age-related deficits in motor abilities that may reflect structural and chemical changes in the aging brain.


OBJECTIVE
To delineate age-related changes in the physiology of brain systems subserving simple motor behavior.


METHODS
Ten strongly right-handed young (<35 years of age) and 12 strongly right-handed elderly (>50 years of age) subjects with no evidence of cognitive or motor deficits participated in the study. Whole-brain functional imaging was performed on a 1.5-T MRI scanner using a spiral pulse sequence while the subjects performed a visually paced "button-press" motor task with their dominant right hand alternating with a rest state.


RESULTS
Although the groups did not differ in accuracy, there was an increase in reaction time in the elderly subjects (mean score plus minus SD, young subjects = 547 +/- 97 ms, elderly subjects = 794 +/- 280 ms, p < 0.03). There was a greater extent of activation in the contralateral sensorimotor cortex, lateral premotor area, supplementary motor area, and ipsilateral cerebellum in the elderly subjects relative to the young subjects (p < 0.001). Additional areas of activation, absent in the young subjects, were seen in the ipsilateral sensorimotor cortex, putamen (left > right), and contralateral cerebellum of the elderly subjects.


CONCLUSIONS
The results of this study show that elderly subjects recruit additional cortical and subcortical areas even for the performance of a simple motor task. These changes may represent compensatory mechanisms invoked by the aging brain, such as reorganization and redistribution of functional networks to compensate for age-related structural and neurochemical changes.
Mattay
V S
VS
Clinical Brain Disorders Branch, Intramural Research Program, National Institute of Mental Health, NIH, Bethesda, MD 20892-1379, USA. vsm@helix.nih.gov
Fera
F
F
Tessitore
A
A
Hariri
A R
AR
Das
S
S
Callicott
J H
JH
Weinberger
D R
DR
D000328:Adult; D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D001921:Brain / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D011597:Psychomotor Performance / Q000502:physiology*