Modeling operant behavior in the Parkinsonian rat.

Mathematical principles of reinforcement (MPR; Killeen, 1994) is a quantitative model of operant behavior that contains three parameters representing motor capacity (delta), motivation (a), and short term memory (lambda). The present study applied MPR to characterize the effects of bilateral infusions of 6-OHDA into the substantia nigra pars compacta in the rat, a model of Parkinson's disease. Rats were trained to lever press under a 5-component fixed-ratio (5, 15, 30, 60, and 100) schedule of food reinforcement.