This study uses an operant, behavioral model to assess the daily changes in the decay rate of shortterm memory, motivation, and motor ability in rats exposed to chronic restraint. Restraint decreased reward-related motivation by 50% without altering memory decay rate or motor ability. Moreover, chronic restraint impaired hippocampal-dependent spatial memory on the Y maze (4-hr delay) and produced CA3 dendritic retraction without altering hippocampal-independent maze navigation (1-min delay) or locomotion. Thus, mechanisms underlying motivation for food reward differ from those underlying Y maze exploration, and neurobiological substrates of spatial memory, such as the hippocampus, differ from those that underlie short-term memory. Chronic restraint produces functional, neuromorphological, and physiological alterations that parallel symptoms of depression in humans.

Mathematical Principles of Reinforcement (MPR) is a theory of reinforcement schedules. This paper reviews the origin of the principles constituting MPR: arousal, association and constraint. Incentives invigorate responses, in particular those preceding and predicting the incentive. The process that generates an associative bond between stimuli, responses and incentives is called coupling. The combination of arousal and coupling constitutes reinforcement. Models of coupling play a central role in the evolution of the theory. The time required to respond constrains the maximum response rates, and generates a hyperbolic relation between rate of responding and rate of reinforcement. Models of control by ratio schedules are developed to illustrate the interaction of the principles. Correlations among parameters are incorporated into the structure of the models, and assumptions that were made in the original theory are refined in light of current data.

Twelve pigeons were exposed to negative automaintenance contingencies for 17-27 sessions immediately after brief (14-16 sessions) or extended (168-237 sessions) exposure to positive automaintenance contingencies, or after 4-10 sessions of instrumental training. In all conditions, negative automaintenance contingencies virtually eliminated responding, reducing response rates to an average 1.3 responses per min. This reduction in response rate was validated by a model of transition between early and late response rates that assumed exponential transition of rates from one set of contingencies to the next. The model faithfully reproduced cumulative records, and yielded estimates of terminal rates under negative automaintenance that were close to operant level.

Like other accounts of conditioned inhibition, behavior systems predicts (and Experiment 1 shows) that during summation and retardation tests, presentation of a negative conditioned stimulus (a CS2) created by discriminative Pavlovian food conditioning will interfere with a focal search response, such as nosing in the feeder. Unlike most other views, behavior systems predicts (and Experiment 2 shows) that the same CS2 can potentiate a general search response, like attending to a moving artificial prey stimulus. Contacting the prey stimulus in extinction increased over baseline when a CS2 but not a CS Novel preceded it. Experiment 3 showed this effect was not due to unconditioned qualities of the CS2. It appears that the effects of a discriminative CS2 depend on the interaction of the training contingency with search modes related to the unconditioned stimulus (US), their perceptual-motor repertoires and environmental support, and the choice of response measure.