A pre-clinical study showing how dopaminergic drugs administered during pre-exposure can impair or facilitate latent inhibition.
BACKGROUND
It has been suggested that, in classical conditioning, dopamine (DA) codes for (a) attention to the conditioned stimulus (CS) or (b) the intensity of the unconditioned stimulus.


OBJECTIVE
To clarify the role of DA in pre-clinical classical conditioning studies.


METHODS
An existing model of classical conditioning presented by Schmajuk, Lam, and Gray (J Exp Psychol Anim Behav Process 22:321-349, 1996) suggests that DA cells in the ventral midbrain area code for the attentionally modulated internal representation of the CS. It is assumed that this representation is increased by dopaminergic agonists and decreased by dopaminergic antagonists. Computer simulations with the model describe the effect of nicotine and haloperidol on latent inhibition.


RESULTS
Simulations replicate experimental results demonstrating that both nicotine and haloperidol affect latent inhibition when administered during the pre-exposure phase. In addition, the model reproduces data showing that administration of nicotine or haloperidol results in the impairment or facilitation of latent inhibition depending on the duration of CS or the number of CSs.


CONCLUSIONS
The model demonstrates that pre-clinical experimental results, including cell activity and pharmacological data, are consistent with an attentional role for DA in classical conditioning.
Schmajuk
N A
NA
Department of Psychological and Brain Sciences, Duke University, Durham, NC 27708, USA.
Gray
J A
JA
Larrauri
J A
JA
D003198:Computer Simulation; D003214:Conditioning, Classical / Q000187:drug effects / Q000502:physiology; D018491:Dopamine Agonists / Q000008:administration & dosage* / Q000493:pharmacokinetics; D004334:Drug Administration Schedule; D004353:Drug Evaluation, Preclinical / Q000379:methods* / Q000639:trends; D006220:Haloperidol / Q000494:pharmacology; D006801:Humans; D007266:Inhibition, Psychological; D008959:Models, Neurological; D009538:Nicotine / Q000494:pharmacology; D011600:Psychopharmacology / Q000379:methods / Q000639:trends; D013997:Time Factors
D018491:Dopamine Agonists; D009538:Nicotine; D006220:Haloperidol