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Assessing the Effects of Neuroleptics
on Motor and Motivational Systems: The Barrier Choice Paradigm. Research in neuroscience has shown that dopamine antagonist act upon motor and motivational systems. This presentation summarizes the results obtained with a novel method, the barrier choice paradigm, that has been successfully employed to assess the selective effects of neuroleptics on motor and motivational systems. A standard choice situation for rats was modified by placing a wire mesh barrier between two levers. Rats had to climb this barrier to switch from one lever to the other. In two studies the height of the barrier was increased, or the rate of reinforcement was varied, across levers. Four doses of haloperidol were assessed ( ip) for their effects on climbing the barrier and lever pressing. The results showed that: 1. Climbing the barrier decreased with increasing barrier size and increasing doses of haloperidol. 2. The rats stayed longer on the levers, made more presses, and obtained more reinforcers when injected with the highest doses or when climbing the tallest barriers. 3. The slope of the generalized matching law decreased with increasing doses of haloperidol, showing reductions in the rat's sensitivity to reinforcement. These results support the notion that neuroleptics impair the initiation or execution of complex motor acts and disrupt food-locomotion activity. Keywords: haloperidol, locomotion, sensitivity, barrier, rats. |
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