Objective: To elucidate the role of dopamine in computing reward prediction error signals in the basal ganglia

Background: Phasic discharges of midbrain dopamine neurons are correlated with reward prediction error (RPE). Dopamine neurons send diffuse projections and hence broadcast RPE signals to diverse areas of the brain. However, signals necessary to compute RPE converge in dopaminoceptive regions of the brain, suggesting these brain areas might compute RPE independent of dopaminergic RPE signals

Method: To test whether RPE-related striatal neural activity is dependent upon dopaminergic neuronal activity, we examined effects of dopamine depletion on RPE-related striatal neural activity during a probabilistic Pavlovian conditioning task. We depleted ~80% of dorsal striatal dopaminergic terminals unilaterally using 6-hydroxydopamine, and its functional consequence was confirmed by amphetamine-induced ipsiversive rotation behavior

Results: Seven rats were trained in a probabilistic Pavlovian conditioning task. Dopamine depeletion was acquired with injection of 6-OHDA. Unilateral dorsal striatal dopamine depletion significantly increased reaction time in the probabilistic Pavlovian conditioning task. However, RPE-related striatal neural signals were not mitigated by dopamine depletion

Conclusion: Our results support the view that RPE is computed locally in the dorsal striatum independent of dopaminergic inputs.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/dopamine-depletion-does-not-mitigate-striatal-reward-prediction-error-signals/