Effects of GABA modulators on the repeated acquisition of response sequences in squirrel monkeys.

The present study investigated the effects of positive and negative GABA(A) modulators under three different baselines of repeated acquisition in squirrel monkeys in which the monkeys acquired a three-response sequence on three keys under a second-order fixed-ratio (FR) schedule of food reinforcement. In two of these baselines, the second-order FR schedule and the discriminative stimuli for the response sequence were manipulated ("chain-strained" and "tandem-strained"). In the third baseline condition, response-independent tail shock was presented during acquisition of the response sequence.

Effects of pregnanolone alone and in combination with other positive GABAA modulators on complex behavior in rats.

Rationale: Although positive modulators of gamma-aminobutyric acid(A) (GABA(A)) receptors generally produce similar behavioral effects, regardless of which modulatory site on the GABA(A) receptor complex mediates these effects, some differences have been observed between the effects of neuroactive steroids and those of other positive GABA(A) modulators.

Objective: The current study was designed to compare the behavioral effects of a neuroactive steroid to those of other positive GABA(A) modulators.

Methods: Rats responded under a multiple schedule of repeated acquisition and performance of response chains, with responding maintained under a second-order fixed-ratio 2 schedule of food presentation.

Effects of triazolam, 8-OH-DPAT, and buspirone on repeated acquisition in squirrel monkeys.

The nonserotonergic benzodiazepine, triazolam, was compared with two 5-HT1A receptor agonists, 8-OH-DPAT and buspirone, in squirrel monkeys responding under a repeated-acquisition procedure. In each session, subjects acquired a 4-response sequence by responding sequentially on 3 keys in the presence of 4 discriminative stimuli (colors). Response sequences for each session were maintained by food presentation under a second-order fixed-ratio schedule.

Effects of fenfluramine, m-CPP and triazolam on repeated-acquisition in squirrel monkeys before and after neurotoxic MDMA administration.

Rationale: Establishing functional deficits as a result of neurotoxic dosing regimens of MDMA has been difficult. However, moderate success has been achieved when sensitive animal models and drug challenge have been used together.

Objective: The present study used a repeated-acquisition technique and dose-effect determinations before, during and after neurotoxic MDMA exposure to characterize the effects of serotonergic drugs on learning, and to determine if MDMA-induced serotonin (5-HT) neurotoxicity is associated with learning deficits as measured by changes in response rate or the percentage of errors.