Brain damage and reorganization of function in old age

Abstract

Old-age rats given one-stage bilateral lesions of the frontal cortex were impaired on a shock avoidance task but were unimpaired on a spatial alternation problem, though both tasks are equally sensitive to removal of this same area in fully mature but younger rats. Old-age rats also failed to exhibit the sparing of function typical of younger adults when the frontal cortex is removed in sequential operations. The lack of impairment on the spatial task in senescent rats with frontal lesions is attributable to a relative deterioration in the performance of old-age controls, which take longer to learn the task than younger intact adults. Histological examination of the thalamic projection areas to frontal cortex in old-age rats revealed considerable cell loss in the intact as well as the brain-damaged cases. The results indicate a possible shift in some of the functions of the frontal cortex with advancing age.