AN EXPERIMENTAL ANALYSIS OF THE EFFECTS OF d‐AMPHETAMINE AND COCAINE ON THE ACQUISITION AND PERFORMANCE OF RESPONSE CHAINS IN MONKEYS

Abstract

In one component of a multiple schedule of food presentation, monkeys acquired a different four-response chain each session by responding sequentially on three keys in the presence of four geometric forms (learning). In the other component, the four-response chain was the same each session (performance). Both d-amphetamine and cocaine, at the higher doses, disrupted the behavior in the learning component; the overall response rate decreased, the overall accuracy was impaired (i.e., percent errors increased), and there was less within-session error reduction. The performance component was generally less sensitive than the learning component to the disruptive effects of both drugs on rate and accuracy. After prefeeding or during an extended session, the response rate decreased in both components, but accuracy was generally unaffected. When the four discriminative stimuli in both components were removed, the behavior was disrupted to a greater extent in the performance component. The disruptive effects of both drugs on behavior in the learning component were attenuated when the drugs were administered during the session after the response chain had been acquired. It was concluded that the greater sensitivity of the learning component to disruptive drug effects is related to the relatively weak stimulus control and/or the lower rate of reinforcement associated with that component.Key words: repeated acquisition, multiple schedule, response chains, d-amphetamine, cocaine, prefeeding, stimulus control, key press, monkeysPrevious research has shown that repeatedacquisition baselines are sensitive to the effects of d-amphetamine and cocaine in rats (Schrot, Boren, Moerschbaecher, & Simoes Fontes, 1978) and pigeons (Moerschbaecher, Boren, Schrot, & Simoes Fontes, 1979;Thompson, 1973Thompson, , 1977Thompson, , 1978. In Thompson's experiments, pigeons acquired a different four-response chain each session by responding sequentially on three keys in the presence of four colors. As the dose of each drug was increased, the overall response rate decreased, the overall accuracy was impaired (i.e., percent errors increased), and there was less within-session error reduction (acquisition). Similar disruptive drug effects were obtained in the Moerschbaecher et al. (1979)

Comparison of Drug Effects on Fixed‐ratio Performance and Chain Performance Maintained Under a Second‐order Fixed‐ratio Schedule

“…The generality of the finding that pigeons' acquisition and performance in a conditional discrimination task were differentially sensitive to the effects of d-amphetamine was extended in two experiments with patas monkeys responding in a task more closely related to that used in the present study (Thompson & Moerschbaecher, 1979). In one component of a multiple schedule, the monkeys acquired a different four-response chain each session by responding sequentially on three keys in the presence of four geometric forms.…”

“…Given the finding that the acquisition of a response chain was more readily disrupted by d-amphetamine than was the performance of an established response chain (Thompson & Moerschbaecher, 1979), the question arose as to whether this type of performance baseline would differ from less complex schedule-controlled performance in terms of sensitivity to drug effects. Accordingly, in the present research a multiple schedule was used to compare drug effects on well established simple and complex operant performance in pigeons.…”

Acute Cocaine Administration Depresses Cortical Activity

“…Furthermore, transient changes in cortical excitability may have a role in mediating some of the short-term behavioral effects of cocaine. For example, acute cocaine administration to monkeys has been shown to impair performance in a behavioral paradigm that involves new learning as well as behavioral flexibility (Thompson and Moerschbaecher, 1970;Evans and Wenger, 1992;Jentsch et al, 2002). The cocaine-induced decrease in cortical bistability reported here could contribute to decrease efficiency of information processing in prefrontal cortex and compromise functions such as working memory and attention.…”

7-Chloro-3-methyl-3,4-dihydro-2H-1,2,4-benzothiadiazine S,S-dioxide (IDRA 21), a congener of aniracetam, potently abates pharmacologically induced cognitive impairments in patas monkeys.

“…It has been reported that attention-improving drugs can increase motor performance and antagonize benzodiazepine-induced sedation or anxiolytic action but cannot consistently enhance acquisition (34,35) or reverse benzodiazepine-induced impairment in recall (36,37 We have obtained preliminary data showing that the lack of effect of cognition-enhancing drugs in improving acquisition in normal animals is related to the difficulty level of the behavioral task. In the present research with normal monkeys, the acquisition component required that the monkey learn a four-response chain by pressing in sequence three response keys labeled by four geometric forms.…”