Reward-related limbic memory and stimulation of the cannabinoid system: An upgrade in value attribution?
J Psychopharmacol. 2017-09-07; 32(2): 204-214
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While a lot is known about the mechanisms promoting aversive learning, the impact
of rewarding factors on memory has received comparatively less attention. This
research investigates reward-related explicit memory in male rats, by taking
advantage of the emotional-object recognition test. This is based on the prior
association, during conditioned learning, between a rewarding experience (the
encounter with a receptive female rat) and an object; afterwards rat
discrimination and recognition of the ’emotional object’ is recorded in the
presence of a novel object, as a measure of positive limbic memory formation.
Since endocannabinoids are critical for processing reward and motivation, the
consequences of the stimulation of cannabinoid signalling are also assessed by
the administration of WIN 55,212-2 at pre- and post-conditioning time. Our
results show that rats encode the association between object and rewarding
experience, form positive limbic memory of the emotional object, and retrieve
this information in the face of novelty. Stimulation of the cannabinoid system at
pre-conditioning time is able to strengthen reward-related explicit memory in the
presence of novelty, whereas post-conditioning activation increases approach
behaviour to novel stimuli. The assessment of limbic memory by the
emotional-object recognition test can help unveiling the addictive and
confounding properties of psychotropic drugs.