The barrier choice paradigm: haloperidol reduces sensitivity to reinforcement

The standard choice situation was modified by placing a 76 cm high barrier between two levers. To travel between levers, rats had to climb the barrier . Four doses of haloperidol were assessed for effects on motor and motivati onal systems. The drug impeded the rats' ability to climb the barrier. Resi dence and travel times increased, and changeover rates decreased. Pressing the levers was not entirely suppressed by haloperidol. The slope of the mat ching law decreased with increasing doses of haloperidol, showing reduction s in the rats' sensitivity to reinforcement. The notion that neuroleptics i mpair the initiation or execution of complex motor acts and disrupt food-lo comotion activity, is supported by these results. (C) 1999 Elsevier Science B.V. All rights reserved.