Dopamine dependency for acquisition and performance of Pavlovian conditioned response

Abstract

During Pavlovian conditioning, pairing of a neutral conditioned stimulus (CS) with a reward leads to conditioned reward-approach responses (CRs) that are elicited by presentation of the CS. CR behaviors can be sign tracking, in which animals engage the CS, or goal tracking, in which animals go to the reward location. We investigated CR behaviors in mice with only ∼5% of normal dopamine in the striatum using a Pavlovian conditioning paradigm. These mice had severely impaired acquisition of the CR, which was ameliorated by pharmacological restoration of dopamine synthesis with L-dopa. Surprisingly, after they had learned the CR, its expression decayed only gradually in following sessions that were conducted without L-dopa treatment. To assess specific contributions of dopamine signaling in the dorsal or ventral striatum, we performed virus-mediated restoration of dopamine synthesis in completely dopamine-deficient (DD) mice. Mice with dopamine signaling only in the dorsal striatum did not acquire a CR, whereas mice with dopamine signaling only in in the ventral striatum acquired a CR. The CR in mice with dopamine signaling only in the dorsal striatum was restored by subjecting the mice to instrumental training in which they had to interact with the CS to obtain rewards. We conclude that dopamine is essential for learning and performance of CR behavior that is predominantly goal tracking. Furthermore, although dopamine signaling in the ventral striatum is sufficient to support a CR, dopamine signaling only in the dorsal striatum can also support a CR under certain circumstances.

Stimulation of dopamine D 1 receptor improves learning capacity in cooperating cleaner fish

“…Recently, Darvas et al [70] found that animals are capable of associative learning with as little as 30% of baseline DA levels. Additionally, DA blockade may only impair associative learning in animals with a tendency to learn through a form of stimulus-reward learning where DA-mediated incentive salience is attributed to reward cues [10,71,72], but not of those forms that instead rely on the predictive value of such reward cues [70]. Here, none of the administered antagonists (D 1 and D 2 ) delayed the cleaners' learning ability in either of the two tasks, probably because DA signalling did not decrease to a degree where it would compromise the acquisition of a basal conditioned response.…”

Effects of the modern food environment on striatal function, cognition and regulation of ingestive behavior

“…Food cues acquire reinforcing properties via Pavlovian conditioning [7], in which a once neutral cue is associated with nutrient ingestion. Once this association is formed, food cues gain access to reward [8] and homeostatic circuits [9], thereby acquiring the ability to elicit reflexive responses such as cephalic phase responses [10], food seeking [11], and craving [6].…”

Relative contributions of severe dopaminergic neuron ablation and dopamine depletion to cognitive impairment

“…In the first model (DAT:TH-KO), DA synthesis is abolished through genetic inactivation of the tyrosine hydroxylase ( Th ) gene in all DA-transporter (DAT) expressing neurons, which make up the majority of midbrain DA neurons (Darvas et al, 2014b; Henschen et al, 2013). Importantly, in this model DA neurons are still present and otherwise intact.…”