Novel-object place conditioning: behavioral and dopaminergic processes in expression of novelty reward.
In a choice situation, rats given repeated access to novel objects in one of two distinct environments display an increase in preference for the novelty-paired environment. The experiments in this present report extend the generality of this effect to new procedures. Further, this shift in preference depends on object novelty; no systematic shift in preference was observed if the environment was paired with a familiar object. Experiments in the present report also provided evidence against non-associative accounts that rely on mechanisms that leave the paired environment more novel than the unpaired environment (e.g. object interaction interfering with environmental familiarization). Consistent with a conditioning account is the loss of place conditioning when access time with the novel objects was shortened from 10 min to 5 or 2.5 min. Interestingly, although a decrease in time with objects prevented place conditioning, these groups showed a novelty-conditioned increase in activity. Finally, treatment with the dopamine D(1) antagonist SCH-23390 (0.03 mg/kg) or the dopamine D(2)/D(3) antagonist eticlopride (0.1 mg/kg) before the post-conditioning preference test blocked expression of the novel-object place conditioning. Taken together, these experiments establish that the increased preference produced by object-environment pairings reflects a conditioned association between environmental cues and the appetitive effects of receiving access to novel stimuli.
Bevins
Rick A
RA
Department of Psychology, University of Nebraska-Lincoln, Lincoln, NE 68588-0308, USA. rbevins1@unl.edu
Besheer
Joyce
J
Palmatier
Matthew I
MI
Jensen
Heather C
HC
Pickett
Katherine S
KS
Eurek
Sarah
S
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology*; D001552:Benzazepines / Q000494:pharmacology; D003216:Conditioning, Operant / Q000187:drug effects / Q000502:physiology*; D003463:Cues; D004298:Dopamine / Q000502:physiology*; D018492:Dopamine Antagonists / Q000494:pharmacology; D004777:Environment; D005793:Generalization, Psychological; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D017447:Receptors, Dopamine D1 / Q000187:drug effects; D017448:Receptors, Dopamine D2 / Q000187:drug effects; D050637:Receptors, Dopamine D3; D012201:Reward; D012457:Salicylamides / Q000494:pharmacology
D001552:Benzazepines; D018492:Dopamine Antagonists; C493595:Drd3 protein, rat; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D050637:Receptors, Dopamine D3; D012457:Salicylamides; C045989:eticlopride; D004298:Dopamine