Organization of reward and movement signals in the basal ganglia and cerebellum

The basal ganglia and the cerebellum are major subcortical structures in the motor system. The basal ganglia have been cast as the reward center of the motor system, whereas the cerebellum is thought to be involved in adjusting sensorimotor parameters. Recent findings of reward signals in the cerebellum have challenged this dichotomous view. To compare the basal ganglia and the cerebellum directly, we recorded from oculomotor regions in both structures from the same monkeys. We partitioned the trial-by-trial variability of the neurons into reward and eye-movement signals to compare the coding across structures. Reward expectation and movement signals were the most pronounced in the output structure of the basal ganglia, intermediate in the cerebellum, and the smallest in the input structure of the basal ganglia. These findings suggest that reward and movement information is sharpened through the basal ganglia, resulting in a higher signal-to-noise ratio than in the cerebellum.

基底神经节（basal ganglia）与小脑（cerebellum）是运动系统中的主要皮层下结构。传统观点认为，基底神经节是运动系统的奖赏中枢，而小脑则负责调节感觉运动参数。近期在小脑中发现的奖赏信号，对这一二分认知提出了挑战。为直接对比基底神经节与小脑的功能差异，我们从同一批猕猴的两种结构的动眼脑区中进行了神经记录。我们将神经元的逐试次变异分解为奖赏信号与眼动信号，以比较二者的编码特征。结果显示，奖赏预期与运动信号在基底神经节的输出结构中最为显著，在小脑中处于中等水平，而在基底神经节的输入结构中最弱。上述发现表明，奖赏与运动信息会在基底神经节中得到精细化处理，最终获得比小脑中更高的信噪比。