Pair housing, but not using a controlled reinforcer frequency procedure, attenuates the modulatory effect of probability presentation order on amphetamine-induced changes in risky choice.

Probability discounting is often measured with independent schedules. Independent schedules have several limitations, such as confounding preference for one alternative with frequency of reward presentation and generating ceiling/floor effects at certain probabilities. To address this potential caveat, a controlled reinforcer frequency schedule can be used, in which the manipulandum that leads to reinforcement is pseudo-randomly determined before each trial.

Effects of d-amphetamine and MK-801 on impulsive choice: Modulation by schedule of reinforcement and delay length.

Procedural modifications can modulate drug effects in delay discounting, such as signaling the delay to reinforcement and altering the order in which delays are presented. Although the schedule of reinforcement can alter the rate at which animals discount a reinforcer, research has not determined if animals trained on different schedules of reinforcement are differentially affected by pharmacological manipulations. Similarly, research has not determined if using different delays to reinforcement can modulate drug effects in delay discounting.

Group I metabotropic glutamate receptor antagonists impair discriminability of reinforcer magnitude, but not risky choice, in a probability-discounting task.

The glutamatergic system has been identified as an important mediator of risky choice. However, previous studies have focused primarily on ionotropic glutamate receptors (e.g.