Role of Dopamine in the Primate Caudate Nucleus in Reward Modulation of Saccades

Abstract

Expected reward impacts behavior and neuronal activity in brain areas involved in sensorimotor processes. However, where and how reward signals affect sensorimotor signals is unclear. Here, we show evidence that reward-dependent modulation of behavior depends on normal dopamine transmission in the striatum. Monkeys performed a visually guided saccade task in which expected reward gain was different depending on the position of the target. Saccadic reaction times were reliably shorter on large-reward trials than on smallreward trials. When position-reward contingency was switched, the reaction time difference changed rapidly. Injecting dopamine D 1 antagonist into the caudate significantly attenuated the reward-dependent saccadic reaction time changes. Conversely, injecting D 2 antagonist into the same region enhanced the reward-dependent changes. These results suggest that reward-dependent changes in saccadic eye movements depend partly on dopaminergic modulation of neuronal activity in the caudate nucleus.

Functional Connectivity of the Striatum Links Motivation to Action Control in Humans

“…This interfacing function of the caudate parallels findings from a number of primate studies that have underlined the role of the caudate in transforming motivational information into eyemovement signals (Sato and Hikosaka, 2002;Hikosaka et al, 2006;Nakamura and Hikosaka, 2006). Many caudate neurons fire not only before the onset of an expected saccade target, but also in preparatory responding to signals that predict reward.…”

How motivation and reward learning modulate selective attention

“…To sum up, dopamine modulation of midbrain neurons (striatum/caudate nucleus) may signal the difference between expected and actual reward, and then influence various brain systems involved in attention and motivation as well as decisionmaking (Hikosaka, 2007;Nakamura and Hikosaka, 2006;Pessiglione et al, 2006;Yamamoto et al, 2013). Stable and flexible representations of values encoded in the caudate nucleus might be transmitted to the superior colliculi via different parts of the substantia nigra, in order to bias sensorimotor behaviors toward rewarded information.…”

Activation of Nigral and Pallidal Dopamine D1-Like Receptors Modulates Basal Ganglia Outflow in Monkeys

“…The lack of effect of the D1LR antagonist in the SNr, measured during behavioral "idling," as in our study, may not reflect the true behavioral importance of the neuromodulator. It remains to be seen whether locally injected dopamine receptor antagonists would interfere with behavioral performance or influence neuronal spiking during the performance of tasks, as was shown for D1LR antagonist injections into striatum and frontal cortex (Nakamura and Hikosaka 2006;Williams and Goldman-Rakic 1995).…”