Aged F344 rats exhibit altered electrophysiological activity in locomotor-unrelated but not locomotor-related striatal neurons

Multi-wire electrode arrays were chronically implanted and striatal electrophysiological activity was recorded in young (4-9 months) versus aged (24-29 months) Fischer 344 (F344) rats in order to determine whether locomotor-related striatal neurons exhibit age-related changes in electrophysiological activity during freely-moving conditions. Individual neurons were classified as locomotor-related if they exhibited significant differences in their firing rates between periods of locomotion versus periods of non-movement. While the activity of locomotor-related striatal neurons did not differ between young and aged rats, neurons that were not related to locomotion exhibited significantly greater activity in the aged rats during both periods of non-movement and bouts of locomotion. These results suggest that in the aged striatum, increased activity of nonlocomotor-related neurons may contribute to hypokinesia through their influence on basal ganglia output nuclei. Such studies may aid in the understanding of movement disorders seen in aging and Parkinson's disease.