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Effects of Haloperidol on Cue Controlled Lever Pressing Behavior in the Rat

Arzu Özkan, Levent Şenyüz
2005; 20(56):01-24

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The current study examined whether the presence and absence of discrete environmental stimuli controlling water reinforced lever-pressing response could change the well known behavior attenuating effects of dopamine D2 receptor antagonist haloperidol (0.00, 0.08, 0.16 and 0.32 mg/kg, ip). 21 rats were trained to bar press to obtain water, and then, divided into three groups. One of the groups was the control group. Remaining two groups of rats were trained to bar press to obtain water in the presence of either an auditory (sound group) or a visual cue (light group). The number of lever-pressing responses for the subjects were recorded in the presence (S+) and absence (S-) of environmental stimuli and reinforcer. Haloperidol suppressed the mean number of responses for all groups, regardless of stimulus conditions. However, the index of persistence obtained for each subject by dividing the number of responses emitted during the presence of respective environmental cue to the number of total responses executed by the same subject under the same conditions, remained the same after haloperidol pretreatment. The results showed that although haloperidol attenuated the number of operant lever-pressing responses, the conditioned motivational properties of environmental cues are unaltered by treatment with the same D2 receptor antagonist.

Keywords: Haloperidol, dopamine, D2 receptors, incentive motivation, rat, lever pressing, stimulus control