Functional roles of cerebrocerebellar communication system in prism adaptation of reaching

在我们的大脑中，从视觉空间到运动空间的坐标转换是实现手臂到达目标的必要条件。由于发现腹侧运动前皮层和小脑在感觉运动整合和棱镜适应中起着重要作用，本研究探讨了脑小脑通讯系统在运动执行和学习中的作用。首先，将少量的神经解剖示踪剂（生物素化右旋糖酐胺，BDA）注射到猴子的PMv中，发现标记的神经元密集分布在运动丘脑的X区，而运动丘脑是反映视觉空间的运动相关活动最频繁的神经元。其次，在每次试验的准备阶段，在执行手腕伸展和弯曲任务的猴子中，从电生理学上识别了投射到皮层运动区域（包括PMv）的丘脑神经元，该任务的运动方向是由听觉线索指示的，然后是三种感觉信号（视觉、听觉或触觉）中的一种来启动运动。在皮层运动区，神经元记录了两种主要的任务相关活动：(1)运动相关活动，在运动开始前立即发生阶段性变化；(2)设置相关活动，在指令信号出现后的整个准备期间持续变化。大多数活动都有手腕运动方向的偏好。相比之下，没有记录到信号相关的神经元活动和模态特定运动相关的活动，尽管这些活动在皮质运动区经常观察到。结果表明，从小脑到皮层运动区的投射系统在运动参数的确定和运动启动中起重要作用，但对坐标转换所必需的感觉运动转换的作用较小。少

Transformation of coordinates from visual to motor space in our brain is essential to achieve target-reaching by arm. Since it was found that the ventral premotor cortex(PMv) as well as cerebellum plays an important role in the sensorimotor integration and prism adaptation, it was investigated in this study how the cerebrocerebellar communication system contribute to the motor execution and learning. First, when a small amount of neuroanatomical tracer(Biotinylated Dextran Amine,BDA) was injected in to the PMv of monkeys where neurons with movement-related activity reflecting visual space were most frequently recorded, it was found that labeled neurons were densely located in area X of the motor thalamus. Second, thalamic neurons projecting to the cortical motor areas including the PMv were identified electrophysiologically in monkeys performing a wrist extension and flexion task in which the movement direction was instructed by auditory cues during the preparation period in each trial … More , followed by one of the three type of sensory signals(visual, auditory, or tactile) to initiate the movement. Two major task-related activities were recorded from the neurons, as found in the cortical motor areas : (1)movement-related activity with phasic changes immediately before movement onset and (2)set-related activity, a sustained change of activity throughout the preparation period after the instruction signal was presented. A majority of the activities were found to have preference for wrist movement directions. By contrast, no signal-related neuronal activity and modality specific movement-related activity were recorded, although such activities were frequently observed in the cortical motor areas. The results suggest that the projection system from the cerebellum to the cortical motor areas plays important roles in determination of movement-parameters and movement initiation, but contribute much less to sensorimotor conversion which is necessary for transformation of coordinates. Less