Age-related behavioral and neurochemical deficits: The cholinergic system revisited

Recently, we began to quantify both the shared and the unique interrelationships between age, behavioral performance, and a neurochemical marker of the cholinergic system in the nonhuman primate. Age-related impairments in choline acetyltransferase (ChAT) activity have been found to be associated with a number of behavioral tasks. The focus here is on changes in ChAT activity that are related to behavioral deficits on a concurrent object discrimination with a 24-hour intertrial interval (24 HR ITI), and a delayed-nonmatch-to-sample task (DNMS). The subjects were 18 rhesus monkeys (Macaca mulatta), 8 males and 10 females weighing 4.5-14.1 kg. At the time of sacrifice, the animals ranged in age from 8 to 34 years. All animals had been behaviorally tested and the data have been reported elsewhere.