Effects of scopolamine on learning and memory in monkeys

Abstract

The effects of scopolamine were evaluated in monkeys responding under operant procedures designed to evaluate drug effects on learning and memory. In one procedure, responding was maintained by food presentation under a multiple schedule. One component of the multiple schedule was a repeated-acquisition task in which the discriminative stimuli for left- and right-key responses changed each session (learning). In the other component, the discriminative stimuli for responses were the same each session (performance). In both components of the multiple schedule, scopolamine produced dose-related decreases in responding; there was little evidence of differential rate-decreasing effects between components. Percent errors in learning were increased in a dose-related manner, whereas percent errors in performance were generally unaffected except at high doses, which also produced substantial decreases in response rate. These results suggest that acquisition is more sensitive to the disruptive effects of scopolamine than is performance. The second procedure utilized repeated acquisition and delayed performance as a technique to study the effects of scopolamine on memory. In this procedure, each session was divided into three phases: acquisition, delay and performance. After a 24-h delay, scopolamine had little or no effect on retention, accuracy or rate of responding. In contrast, after a 60-min delay, scopolamine decreased retention in a dose-related manner. These data suggest that scopolamine produces a greater disruptive effect on short (60-min) versus long (24-h) delays.

The effects of piracetam on morphine-induced amnesia and analgesia: The possible contribution of central opiatergic mechanisms on the antiamnestic effect of piracetam

“…The amnestic effects of these agents have been demonstrated in many other studies using other memory-measuring methods [4,14 19]. Scopolamine appeared to be the most useful amnestic agent, as indicated by many other studies [14][15][16], and thus we used it as a standard amnestic substance to confirm the utility of our method. In contrast to other studies mentioned above, scopolamine, over a wide range of dosages, exerted nearly equivalent effects on learning and memory in these experiments.…”

Hippocampal M1 receptor function associated with spatial learning and memory in aged female rhesus macaques

“…They are present in high concentrations in the prefrontal cortex (PFC) and the hippocampus (Nathanson 2008) and have an integral role in spatial learning and memory in rodents, nonhuman primates, and humans (Wisman et al 2008;Gage et al 1988;Fredrickson et al 2008; Thomas et al 2008). Scopolamine, a nonspecific muscarinic receptor antagonist (Elrod and Buccafusco 1988), impairs cognitive task performance in rats (Biggan et al 1996), dogs (Araujo et al 2005), rhesus monkeys (Savage et al 1996;Taffe et al 1999), and humans (Rosier et al 1998). The most highly expressed muscarinic receptor in the PFC and hippocampus, regions critical for cognitive function, is the type 1 (M1) subtype (Gage et al 1988;Fredrickson et al 2008;Thomas et al 2008;Flynn et al 1995a,b;Tamminga 2006;Wisman et al 2008).…”

The effects of psychotomimetics and psychomotor stimulants on two schedules promoting response switching in the rat

“…The first, exemplified by Moerschbaecher and colleagues (Thompson and Moerschbaecher 1984;Savage et al 1996;Winsauer and Moerschbaecher 2000), is to train animals to make a series of responses in a set order and examine the effects of drugs on either the performance of well-learned sequences or the acquisition of new sequences. In general, drugs induce more erroneous responses during acquisition, when stimulus control is weak, than during performance when it is relatively strong (Thompson and Moerschbaecher 1979).…”