Is extinction the hallmark of operant discrimination?: Reinforcement and SΔ effects

Abstract

Using a successive discrimination procedure with rats, three experiments investigated the contribution of reinforcement rate and amount of S(Delta) exposure on the acquisition of an operant discrimination. S(D) components and were always 2 min in length, while S(Delta) (extinction) components were either 1 min or 4 min in length; responses in S(D) were reinforced on one of four schedules. In Experiment 1, each of eight groups were exposed to one possible combination of rate of reinforcement and S(Delta) component length. At every level of reinforcement, the 4 min S(Delta) groups acquired the discrimination more quickly. However, within each level of reinforcement, the proportions of responding in S(D) as a function cumulative S(Delta) exposure were equivalent, regardless of the number of reinforcers earned in S(D), suggesting that extinction is the "hallmark" of discrimination. Experiment 2 sought to replicate these results in a within-subjects design, and although the 4 min S(Delta) conditions always produced superior discriminations, the lack of discriminated responding in some conditions suggested that stimulus disparity was reduced. Experiment 3 clarified those results and extended the finding that the acquisition of operant discrimination closely parallels extinction of responding in S(Delta). In sum, it appears that higher reinforcement rates and longer S(Delta) exposure facilitate the acquisition of discriminated operant responding.

Transfer of the discriminative stimulus effects of Δ9-THC and nicotine from one operant response to another in rats

“…In the present study, each drug served one role (albeit counterbalanced). Indeed, the S Δ does play a critical function in the regulation of the operant discriminative control (e.g., Andrzejewski et al 2007) and should be considered more in future drug discrimination studies (e.g., Troisi and Akins 2004). Of course, the importance of inhibition in the regulation of behavior, particularly discrimination learning, is not new (Konorski 1948), but intriguing within the context of interoceptive conditioning with drug states (Troisi and Akins 2004).…”

Adenosine A2A receptor and ERK-driven impulsivity potentiates hippocampal neuroblast proliferation

“…Sign-tracking impulsivity during extinction was examined in WT and ENT1 –/– mice during a second-order discrimination. 29 , 30 Detailed methods are provided in the Supplementary Information .…”

The effects of clinically relevant doses of amphetamine and methylphenidate on signal detection and DRL in rats

“…All rats were initially trained to lever press during 9 daily, 30-min sessions, as described elsewhere (Andrzejewski et al, 2007). All rats were lever pressing by the end of training.…”