Reward-related limbic memory and stimulation of the cannabinoid system: An upgrade in value attribution?

Abstract

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.

In utero Δ9-tetrahydrocannabinol exposure confers vulnerability towards cognitive impairments and alcohol drinking in the adolescent offspring: Is there a role for neuropeptide Y?

“…Furthermore, since dysfunctions of the synaptic triad amongst glutamate, GABA and DA in the mesocorticolimbic regions have long been implicated in the underlying pathogenesis of alcohol use disorders (Cannizzaro et al, 2019;Spiga et al, 2014), it is reasonable to suggest that the augmented operant behaviour for alcohol observed in this study can result from prenatal THCinduced aberrant plasticity in specific areas of the brain that are functionally associated with reward, motivation and salience attribution (Brancato et al, 2014(Brancato et al, , 2018bCannizzaro et al, 2019).…”

“…Consistently, prenatal exposure to cannabinoids induces subtle yet persisting changes in cognitive functions that emerge when cognitive abilities require emotional integration (Bara et al, 2018; Mereu et al, 2003; Morena et al, 2015). Indeed, whereas activation of CB1 receptors within the mPFC strongly potentiates normally non-salient emotional memory formation (Brancato et al, 2018b; Laviolette and Grace, 2006; Tan et al, 2014), THC administration alters facial recognition (Hindocha et al, 2015), decreases, in the Amy, blood oxygen level–dependent response to threatening faces (Phan et al, 2008) and preferentially impairs memory for emotional events in humans (Ballard et al, 2013). The mechanisms by which CB1 transmission regulates emotional memory formation are not entirely understood, but a single systemic stimulation of the cannabinoid transmission by the CB1 agonist WIN 55, 212-2 decreases limbic memory in the same Emotional Object Recognition task in adult rats (Brancato et al, 2016).…”

Basal Forebrain Mediates Motivational Recruitment of Attention by Reward-Associated Cues

“…We recently found that disrupting OFC function abolished control of discrimination accuracy by signaled reward probability in our task ( Ward et al, 2015b ; Hall-McMaster et al, 2017 ) similarly to what we found here. Finally, other signaling pathways in the BF-prefrontal circuit, such as the endocannabinoid system, have recently been identified as important in BF modulation of cortical activity and in the processing of reward-driven motivational salience ( Llorente-Ovejero et al, 2017 ; Brancato et al, 2018 ). Clearly, further work that delineates the specific neural populations and timecourse of neural activity involved in SPSA performance is needed in order to clarify the specific role of cholinergic and non-cholinergic BF projections neurons and other circuitry in the effects seen here.…”

The Endocannabinoid System and Cannabidiol's Promise for the Treatment of Substance Use Disorder

“…The limbic system, in particular the amygdala and hippocampus, by supporting the formation of associative memory, promotes positive and negative reinforcement of rewards including those of substances of abuse (58). Indeed, animal models demonstrate memory performance to not only be dependent on emotional processes, but may be modulated by augmentation of ECS signaling (59–62). Phytocannabinoids, such as THC and CBD for example have been found to modulate brain activity level across limbic regions during emotional processing tasks (63, 64).…”