The striatum plays critical roles in visually-guided decision-making and receives dense axonal projections from midbrain dopamine neurons. However, the roles of striatal dopamine in visual decision-making are poorly understood. We trained male and female mice to perform a visual decision task with asymmetric reward payoff, and we recorded the activity of dopamine axons innervating striatum. Dopamine axons in the dorsomedial striatum (DMS) responded to contralateral visual stimuli and contralateral rewarded actions. Neural responses to contralateral stimuli could not be explained by orienting behavior such as eye movements. Moreover, these contralateral stimulus responses persisted in sessions where the animals were instructed to not move to obtain reward, further indicating that these signals are stimulus-related. Lastly, we show that DMS dopamine signals were qualitatively different from dopamine signals in the ventral striatum (VS), which responded to both ipsilateral and contralateral stimuli, conforming to canonical prediction error signaling under sensory uncertainty. Thus, during visual decisions, DMS dopamine encodes visual stimuli and rewarded actions in a lateralized fashion, and could facilitate associations between specific visual stimuli and actions.

SIGNIFICANCE STATEMENT While the striatum is central to goal-directed behavior, the precise roles of its rich dopaminergic innervation in perceptual decision-making are poorly understood. We found that in a visual decision task, dopamine axons in the dorsomedial striatum (DMS) signaled stimuli presented contralaterally to the recorded hemisphere, as well as the onset of rewarded actions. Stimulus-evoked signals persisted in a no-movement task variant. We distinguish the patterns of these signals from those in the ventral striatum (VS). Our results contribute to the characterization of region-specific dopaminergic signaling in the striatum and highlight a role in stimulus-action association learning.

纹状体在视觉引导决策中发挥着关键作用，并接收来自中脑多巴胺神经元的密集轴突投射。然而，人们对纹状体多巴胺在视觉决策中的作用知之甚少。我们训练雄性和雌性小鼠执行具有不对称奖励回报的视觉决策任务，并记录了支配纹状体的多巴胺轴突的活动。背内侧纹状体（DMS）中的多巴胺轴突对对侧视觉刺激和对侧奖励动作做出反应。对对侧刺激的神经反应无法通过眼球运动等定向行为来解释。此外，这些对侧刺激反应在动物被指示不要移动以获得奖励的过程中持续存在，进一步表明这些信号与刺激相关。最后，我们表明 DMS 多巴胺信号与腹侧纹状体（VS）中的多巴胺信号有质的不同，后者对同侧和对侧刺激都有反应，符合感觉不确定性下的典型预测误差信号。因此，在视觉决策过程中，DMS 多巴胺以侧化方式编码视觉刺激和奖励行为，并且可以促进特定视觉刺激和行为之间的关联。

意义陈述虽然纹状体是目标导向行为的核心，但其丰富的多巴胺能神经支配在知觉决策中的确切作用却知之甚少。我们发现，在视觉决策任务中，背内侧纹状体（DMS）中的多巴胺轴突向记录的半球对侧发出刺激信号，以及奖励动作的开始。刺激诱发的信号在无运动任务变体中持续存在。我们将这些信号的模式与腹侧纹状体（VS）中的信号模式区分开来。我们的结果有助于纹状体中区域特异性多巴胺能信号的表征，并强调刺激-动作关联学习中的作用。