THE INFLUENCE OF AGE, HYPOPHYSECTOMY, THYROIDECTOMY, AND THYROXIN INJECTION ON SIMPLE REACTION TIME IN THE RAT.
Thyroxin injection with associated increases in metabolic rate does not significantly affect simple reaction time to an electric shock. Hypophysectomy and thyroidectomy with associated decreases in metabolic rate produce a slight decline in reaction speed. Reaction time is long in young animals, probably due to incomplete development of certain integrative and conductive systems; it remains virtually constant between puberty and relatively advanced age when it increases rapidly, probably due to physicochemical changes in the composition of the conducting nervous system.
Brody
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EB
Departments of Dairy Husbandry and Psychology, University of Missouri, Columbia.