Dopaminergic involvement in latent inhibition
It has been suggested (e.g., Gray, Feldon, Rawlins, Hemsley, & Smith, 1991; Weiner, 1990) that indirect DA agonists increase, and DA receptor antagonists decrease, attention to the preexposed CS, respectively impairing or facilitating LI. This attentional view was challenged by Killcross, Dickinson, and Robbins (1994a, b) who reported that the diminishing effects of amphetamine on LI could be reversed by reducing, and the enhancing effects of α-flupenthixol on LI could be averted by increasing, the intensity of the US used in conditioning. According to Killcross et al, these results would suggest that the abolition of LI by amphetamine and the enhancement of LI by haloperidol and α-flupenthixol is not mediated by changes in attentional processes, but rather by changes in the consequences of reinforcers. In turn, this notion of DA action was challenged by Ruob, Elsner, Weiner, and Feldon (1997) who reported that diminishing effects of amphetamine and enhancing effects of haloperidol on LI could also be averted by manipulating the characteristics of the CS, and by Ruob, Weiner, and Feldon (1998) who demonstrated that the enhancing effects of haloperidol can be precluded by decreasing the intensity of the US.
KeywordsLatent Inhibition Suppression Ratio Lever Press Conditioning Trial Amphetamine Administration
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