Schedule-controlled behavior in rats exposed perinatally to the PCB mixture Aroclor 1254.

Exposure to polychlorinated biphenyls (PCBs) has been shown to detrimentally affect learning and memory in children as well as schedule-controlled behavior in experimental animals. The objective of the present series of experiments was to extend research into the effects of PCBs on behavior maintained under both short (30 s) and long (5 min) fixed-interval (FI) schedules as well as an FI 3-min with reinforcement omission. Long–Evans rats were exposed to 0 or 6 mg/kg/day Aroclor 1254 (A1254) via oral gavage from Gestation Day 6 (GD 6) through Postnatal Day 21 (PND 21). At approximately PND 90, acquisition and steady-state performance were assessed under a series of FI reinforcement schedules consisting of FI 30-s, FI 5-min, and FI 3-min with 33% of the scheduled reinforcers omitted. Performance measures included index of curvature (IOC), response rate, and postreinforcement pause (PRP). There were no effects of A1254 on the acquisition of behavior under the FI 30-s schedule. Subsequently, there was an initial decrease in response rate and IOC and an increase in PRP following the transition from FI 30-s to the FI 5-min; there were, however, no treatment-related effects on any measure. During the reinforcement-omission procedure, there was an increase in the rate of responding and a decrease in IOC and PRP following omission intervals irrespective of treatment. These data are inconsistent with previous findings and suggest that perinatal A1254 exposure in the rat does not disrupt temporally organized behavior.