Drug effects on response-duration differentiation. IV: Effects of trimethyltin.

Trimethyltin (TMT) is a toxicological agent that produces damage in a number of limbic structures, resulting in concomitant disruptions of behavior. The purpose of the present study was to determine the utility of response-duration differentiation (RDD) responding as a behavioral baseline for studying the behavioral consequences of TMT administration. Under the RDD schedule, responses of a restricted duration (1-1.3 s) were reinforced, and disruption of this performance may represent effects upon fine motor control, timing behavior, or both. Two doses of TMT (4 mg/kg) were administered 1 week apart, and behavior under the schedule was studied daily for 6 weeks thereafter in a group of four rats. Additionally, the effects of diazepam (0.1-3mg/kg) administered prior to and following TMT administration were compared. TMT produced disruptions in accuracy of responding and increases in rates of responding in the weeks following its administration. Behavior had generally recovered by 6 weeks after the first TMT administration. Diazepam flattened the relative frequency distributions of response durations at lower doses in the TMT-treated rat. These data show that RDD responding is sensitive to the effects of TMT, and TMT treatment can result in alterations in the effects of diazepam.