Effects of PAL analogs on stereotypy in rats undergoing in vivo microdialysis. Rats received intravenous injection of 1 mg/kg of drug at time 0, followed by 3 mg/kg at 60 min. Stereotypy was determined as described under Materials and Methods; mean basal value for stereotypy was 116 ± 9 episodes/20 min for n = 28 rats. Left, for time course data, stereotypy values are mean ± S.E.M. expressed as a percentage of three preinjection baseline samples (% basal). Arrows indicate times of drug injection. Right, for mean effect data, stereotypy values are the mean ± S.E.M. expressed as the average stereotypy response determined from three postinjection samples after each dose. n = 7 rats/group.