Testing the effect of DA receptor blockers in their absence

Testing the effect of DA receptor blockers in their absence 

One way to overcome the confounding influence of performance impairment in studies of the effect of DA receptor blockers on motivated behavior consists in testing for the action of these drugs in their absence (Beninger, 1989 Ettenberg, 1989). 

These observations could be explained either by an impairment of instrumental response-reinforcement (haloperidol impairs the ability of the reinforcer to strengthen extinguished act-outcome relationships or S-R associations) or of Pavlovian stimulus-reinforcement (haloperidol impairs the ability of the reinforcer to strengthen the incentive properties of the goal box). 

Notwithstanding the above caveats, we favor the interpretation of the effects of neuroleptics in the paradigm of Ettenberg and colleagues as due to an impairment of Pavlovian incentive learning rather than of response reinforcement. These studies also indicate that, once acquired by Pavlovian learning, the expression of the incentive properties of stimuli are resistant to neuroleptics. 

Both the response-energizing and the preparatory roles of DA can be regarded as aspects of an incentive view of the function of DA. Thus, activation of DA transmission by incentive stimuli predictive of reward availability might facilitate the sustained emission of instrumental responses and of appetitive behaviors of search and approach. 

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