Do Pavlovian Processes Really Mediate Behavioral Momentum? Some Conflicting Issues

Behavior Momentum Theory and Humans: A Review of the Literature

Behavioral Momentum Theory (BMT) is often described as analogous to Newton's (1687) laws of motion. That is to say, similar to an object in motion continuing in motion unless acted upon by a force, responses occurring in a static environment will continue to occur at the same rate, unless presented with a disruptor (Nevin, Tota, Torquato, & Shull, Journal of the Experimental Analysis of Behavior, 53, 359-379, 1990). When evaluating response rates through a behavioral momentum framework, responding continuing after a change in reinforcer conditions is said to persist. Previous research conducted with nonhuman animals indicates greater response persistence following conditions with either higher reinforcer rates or higher reinforcer magnitudes (Nevin, Journal of the Experimental Analysis of Behavior, 21(3), 389-408, 1974; Nevin et al., Journal of the Experimental Analysis of Behavior, 53, 359-379, 1990). Although BMT's implications extend across human and nonhuman species, this literature review attempts to provide practitioners and researchers information regarding response persistence across various conditions with human participants.

Can the discriminative stimulus effects of nicotine function concurrently as modulatory opponents in operant and pavlovian occasion setting paradigms in rats?

Nicotine promotes interoceptive changes in the nervous system. Such interoceptive stimuli play important roles in modulating addictive behavior. Operant and Pavlovian stimulus control modulate responsiveness to environmental stimuli related to drug-seeking and self-administration. Nicotine functions as a discriminative stimulus in modulating operant behavior as well as Pavlovian feature stimuli in modulating the conditional responding (CR) to exteroceptive CS→US contingencies. Elucidation of the interaction of these interoceptive stimulus control functions is vital for a comprehensive understanding of nicotine use/abuse, which might lead to better behavioral treatment strategies. This experiment evaluated the interaction among Pavlovian feature positive (FP) and feature negative (FN) effects of nicotine on concurrently occurring operant S^D and S^Δ effects. Sixteen rats were trained in a Pavlovian and operant bidirectional contingency paradigm, using nicotine (0.3 mg/kg) and non-drug (saline) states as interoceptive cues for operant discriminative stimulus conditions (S^D and S^Δ) as well as Pavlovian FP and FN for a light-CS, either leading to a shared food pellet outcome or non-outcome. Nicotine and saline sessions were intermixed. For one group of rats (n = 8), nicotine served as an S^D for lever pressing (variable interval 60 s) and simultaneously functioned as an FN for CS-light→noUS relation on the same sessions. On intermixed sessions, saline served as the S^Δ for lever pressing (non-reinforced) and FP, during which the 8-sec light preceded delivery of the food pellet (variable time ITI = 60 s). For the other group (n = 8) nicotine served as the S^Δ (lever pressing non-reinforced) and FP for the CS, with saline serving in the reverse roles. Consecutive brief non-reinforcement tests revealed that: A) rates of lever pressing were significantly greater in S^D than S^Δ with nicotine and saline suggesting strong operant discriminative stimulus control; B) FP responding to the light CS with nicotine and saline was evident; and C) FN suppression of the CR with nicotine was not evident but weak under saline. These data suggest that nicotine can function as an interoceptive context that hierarchically can enter into concurrently opposing modulatory relations in Pavlovian and operant drug discrimination procedures.