Department of Physiology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, People's Republic of China.
Cerebellum. 2013 Jun;12(3):322-4. doi: 10.1007/s12311-012-0438-7.
Vestibular information arising from rotational head movement and that from translational head movement are detected respectively by the semicircular canal and otolith organ in the inner ear. Spatiotemporal cues are in turn processed by the vestibulo-olivo-cerebellar pathway for sensorimotor coordination, but the role of the inferior olive (IO) in this pathway remains unclear. To address whether rotational and translational movements are differentially represented in the IO, we studied the distribution pattern of IO neurons recruited into the circuitry following selective activation of receptor hair cells of the horizontal semicircular canal or the utricle in adult rats. Neurons in the beta nucleus of IO (IOβ) and dorso-medial cell column of IO were responsive to horizontal translation, but not rotation. Notably, otolith-related neurons were observable largely in the rostral IOβ. In contrast, the subnucleus A of IO (IOA), subnucleus C of IO (IOC), and dorsal cap of Kooy (IOK) were responsive to horizontal rotation, but not translation. In the IOA, these canal-related neurons were clustered in the medial portion of the subnucleus. In the IOC, canal-related neurons were skewed towards the rostral half. In the IOK, canal-related neurons were found throughout the subnucleus. These indicate that the distributions of canal- and otolith-related neurons encoding horizontal motions are clearly segregated in the IO. These discrete IO subnuclei therefore provide a topographic map for temporal and adaptive operations of sensorimotor coordination and spatial reference.
前庭信息分别由内耳的半规管和耳石器官检测到，这些信息来源于头部旋转和平移运动。时空线索依次由前庭橄榄小脑径路处理，用于感觉运动协调，但下橄榄核（IO）在该径路中的作用尚不清楚。为了确定 IO 中是否存在旋转和平移运动的差异表示，我们研究了在成年大鼠中选择性激活水平半规管或耳石的受体毛细胞后，IO 电路中募集的 IO 神经元的分布模式。IOβ核和 IO 背内侧细胞柱中的神经元对水平平移有反应，但对旋转没有反应。值得注意的是，与耳石相关的神经元主要存在于 IOβ的前颅部。相比之下，IO 的 A 亚核（IOA）、IO 的 C 亚核（IOC）和 Kooy 的背帽（IOK）对水平旋转有反应，但对平移没有反应。在 IOA 中，这些与管相关的神经元聚集在亚核的内侧部分。在 IOC 中，与管相关的神经元偏向于前半部分。在 IOK 中，与管相关的神经元分布在整个亚核中。这些表明，编码水平运动的管和耳石相关神经元的分布在 IO 中明显分离。因此，这些离散的 IO 亚核为感觉运动协调和空间参考的时间和适应性操作提供了一个拓扑图。
