Risperidone for aggression and self-injurious behavior in adults with mental retardation.

Risperidone has proven efficacy with reduced likelihood of causing extrapyramidal symptoms in the treatment of schizophrenia. Initial work suggests its utility in the management of aggression and self injury in patients with mental retardation. The use of risperidone in eight adult patients with moderate to profound mental retardation is described.

Choice of timeout from fixed-time schedules: Comparison of two procedures.

Four rats obtained food on fixed-time (FT) 1-, 4-, and 16-min schedules. During FT schedules, a lever press produced a timeout period during which food could not be delivered. When timeout was in effect, a lever press ended the timeout period and reinstated the FT schedule.

Predicting unbound phenytoin concentrations in patients receiving valproic acid: a comparison of two prediction methods.

Objective: To compare the predictive performance of 2 equations that estimate unbound (free) phenytoin plasma concentrations when valproic acid (VPA) and phenytoin are administered concurrently.

Design: Eighty-eight adults receiving VPA and phenytoin concurrently were included in the study. Steady-state plasma concentration measurements of total phenytoin, total VPA, and unbound phenytoin were collected prospectively in the inpatient group (group 1) and retrospectively in the outpatient group (group 2).

Schedule-induced timeout: Effects of timeout-contingent delayed reinforcement.

Rats' lever pressing turned off stimuli associated with various response-independent fixed-time schedules of food delivery and produced a timeout period during which food delivery could not occur. A lever press during timeout turned on the schedule-associated stimuli and reinstated the fixed-time schedule. Every response that produced timeout ended the timing of fixed time intervals; timeout terminating responses started the timing of fixed-time schedules over again.

Timeout induced by differential-reinforcement-of-low-rate schedules.

Three rats pressed a lever for food on differential-reinforcement-of-low-rate (DRL) schedules ranging from 16 s to 96 s. During DRL performance, a response to a second lever turned off chamber illumination and produced a timeout period during which food could not be obtained. During timeout periods, a response to the second lever reinstated the DRL schedule and associated chamber illumination.