Situational specificity of tolerance to effects of phencyclidine on responding of rats under fixed-ratio and spaced-responding schedules.

Responding of rats (n = 5) was maintained under DRL (lever) and Time-Delay (nose-key) schedules of food presentation in different experimental chambers during two separate daily sessions. Tolerance that developed to rate-decreasing effects of phencyclidine for nose-key pressing under the Time-Delay schedule did not extend to effects of phencyclidine on lever pressing under the DRL schedule. In a second experiment, both lever and nose-key pressing of rats were maintained under individual and multiple fixed-ratio schedules. One group of animals (n = 5) experienced both the individual and the multiple schedules in the same experimental chamber and another group (n = 5) experienced the individual and the multiple schedules in different experimental chambers. Tolerance that developed to behavioral effects of phencyclidine during the individual schedule did not extend to responding on even the same manipulandum under the multiple schedule in a different experimental chamber. In contrast, tolerance that developed to behavioral effects of phencyclidine during the individual schedule did extend to responding on even the different manipulandum under the multiple schedule in the same experimental chamber. Thus, tolerance that developed in the environment that was coincident with the pharmacologic actions of phencyclidine did not extend to similar operants in a different environmental condition, but did extend even to a different operant and schedule context in the same environmental condition.