The Impact of Motor Activity and Inactivity on the Brain: Implications for the Prevention and Treatment of Nervous- System Disorders

ABSTRACT— Since Donald Hebb's pioneering observations in the 1940s, much research has focused on the effects of variations in physical activity and environmental complexity on behavioral performance and brain structure. Beneficial effects on brain health have been linked to physical fitness, skilled training, and exposure to complex environments, though in rodents these effects may be negated by sudden changes in social structure. Such manipulations can alleviate the deficits associated with several nervous-system disorders and aging. But how increased activity produces its beneficial effects is still not fully understood. How does unskilled physical activity (e.g., repetitive exercise) compare to training in skilled activities or exposure to complex environments? In injury states, is task-specific training a better rehabilitative strategy than general exercise? How do changes in motor activity affect specific brain regions, and can the intensity and timing of therapeutic movement be adjusted to produce optimal outcomes? Are the beneficial effects of motor enrichment banked over periods of inactivity and can they be called upon with booster training to treat a later neurological disorder? Are there circumstances in which increased activity is harmful? Enrichment of physical activity shows promise as an easy and healthful means for improving or restoring brain function, and questions like these are now being investigated so that the full potential of increased activity may be harnessed.