Use of a fixed consecutive number schedule of reinforcement to investigate the effects of pimozide on behavior controlled by internal and external stimuli.
The effects of the neuroleptic pimozide, a specific dopamine receptor blocker, on behavior maintained under different degrees of stimulus control was examined by using a fixed consecutive number (FCN) schedule of reinforcement with pigeons. This schedule requires that at least eight consecutive responses be made on one key (work key) before a response on a second key (reinforcement key) will be reinforced. For half the birds no change in external stimuli accompanied the eight response (FCN-8) while for the other half the color of the work key changed from white to red after the eight peck (FCN-SD). Both schedules resulted in equal rates of baseline responding. Four doses of pimozide (vehicle, 0.1, 0.3, 0.5 mg/kg) were administered in a Latin Square sequence after baseline responding was stable. Similar pimozide-induced decreases in responding were observed in both conditions. However, pimozide selectively altered response patterns under the FCN-8 condition. The failure of the FCN-SD procedure to display a similar effect demonstrated that the use of salient exteroceptive stimuli can modulate behavioral deficits induced by pimozide. This conclusion has important implications for theories hypothesizing that dopamine subserves reward processes.
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D010856:Columbidae; D003216:Conditioning, Operant / Q000187:drug effects; D004298:Dopamine / Q000502:physiology; D010868:Pimozide / Q000494:pharmacology*; D012055:Reinforcement Schedule
D010868:Pimozide; D004298:Dopamine