Hikosaka O, Takikawa Y, Kawagoe R
Department of Physiology, Juntendo University, School of Medicine, Tokyo, Japan.
Physiol Rev. 2000 Jul;80(3):953-78. doi: 10.1152/physrev.2000.80.3.953.
In addition to their well-known role in skeletal movements, the basal ganglia control saccadic eye movements (saccades) by means of their connection to the superior colliculus (SC). The SC receives convergent inputs from cerebral cortical areas and the basal ganglia. To make a saccade to an object purposefully, appropriate signals must be selected out of the cortical inputs, in which the basal ganglia play a crucial role. This is done by the sustained inhibitory input from the substantia nigra pars reticulata (SNr) to the SC. This inhibition can be removed by another inhibition from the caudate nucleus (CD) to the SNr, which results in a disinhibition of the SC. The basal ganglia have another mechanism, involving the external segment of the globus pallidus and the subthalamic nucleus, with which the SNr-SC inhibition can further be enhanced. The sensorimotor signals carried by the basal ganglia neurons are strongly modulated depending on the behavioral context, which reflects working memory, expectation, and attention. Expectation of reward is a critical determinant in that the saccade that has been rewarded is facilitated subsequently. The interaction between cortical and dopaminergic inputs to CD neurons may underlie the behavioral adaptation toward purposeful saccades.
除了在骨骼运动中发挥众所周知的作用外，基底神经节还通过与上丘（SC）的连接来控制眼球的扫视运动（眼跳）。上丘接收来自大脑皮层区域和基底神经节的汇聚输入。为了有目的地向一个物体进行眼跳，必须从皮层输入中选择合适的信号，而基底神经节在这方面起着关键作用。这是通过黑质网状部（SNr）对上丘的持续抑制性输入来实现的。这种抑制可以通过尾状核（CD）对黑质网状部的另一种抑制作用来消除，从而导致对上丘的去抑制。基底神经节还有另一种机制，涉及苍白球外侧段和底丘脑核，通过该机制可以进一步增强黑质网状部 - 上丘的抑制作用。基底神经节神经元携带的感觉运动信号会根据行为背景受到强烈调节，这反映了工作记忆、期望和注意力。对奖励的期望是一个关键决定因素，因为得到奖励的眼跳随后会得到促进。皮层和多巴胺能输入对尾状核神经元的相互作用可能是朝向有目的眼跳的行为适应的基础。
