Mapping by microstimulation of overlapping projections from area 4 to motor units of the baboon’s hand
Mapping by microstimulation of overlapping projections from area 4 to motor units of the baboon’s hand
复制标题
通过微刺激从区域 4 到狒狒手部运动单位的重叠投影进行映射
DOI：
--
复制
发表时间：
1975
期刊：
影响因子：
--
通讯作者：
T. Powell
中科院分区：
文献类型：
--
作者：
P. Andersen;P. J. Hagan;C. G. Phillips;T. Powell
众所周知，狒狒手部运动单元对皮层刺激的优先可及性取决于锥体神经元群的存在，锥体神经元群单突触地投射到适当的脊髓运动神经元。对这种蚁群结构的完整描述将包括其皮质区域的大小、形状和定位；它能在目标运动神经元中引起的最大单突触去极化量；区域内纹理（输出细胞的密度）的局部变化；以及其领土与其他殖民地所占领领土之间的重叠程度（如果有的话）。系统的皮质内探查用刺激微阴极激发组织球体，其半径，在不同的电流强度下，可以估计在可接受的精度范围内。这样的球体相对于一个菌落的大小来说是很小的，并且可以包含不超过其锥体细胞的一小部分。将这些球体组合在一起，揭示了菌落的大小、形状和质地，以及投射到特定手部肌肉（第一背骨间肌、屈肌和短掌内收肌、指共伸肌）运动神经元池的菌落聚集。它们位于第4区埋在中央沟吻侧壁的那部分。这种聚集体占据了6.0 mm × 5.5 mm的皮质区域。微刺激提供了它们重叠的关键证据。因此，“离散”和“镶嵌”这两个词在描述狒狒皮质运动神经元输出的细粒度结构时没有位置。为了使一个群体中的每个细胞同时放电，必须采用表面刺激。最大输出只能通过目标运动神经元的胞内记录来测量。
It is known that the preferential accessibility of motor units of the baboon’s hand to cortical stimulation depends on the existence of colonies of pyramidal neurons which project monosynaptically to the appropriate spinal motoneurons. A complete description of the architecture of such a colony would include the size, shape and localization of its cortical territory; the maximum quantity of monosynaptic depolarization it can evoke in its target motoneuron; local variations of texture (density of output cells) within the territory; and extent of overlap, if any, between its territory and the territories occupied by other colonies. Systematic intracortical exploration with a stimulating microcathode excites spheres of tissue whose radii, at different current strengths, can be estimated within acceptable limits of accuracy. Such spheres are small in relation to the size of a colony, and can contain no more than a fraction of its pyramidal cells. Piecing these spheres together reveals the size, shape and texture of colonies and of the aggregations of colonies projecting to the motoneuron pools of particular hand muscles (1st dorsal interosseus, flexor and adductor pollicis brevis, extensor digitorum communis).They are localized in that part of area 4 that lies buried in the rostral wall of the central sulcus. Such aggregations occupy cortical territories measuring as much as 6.0 mm × 5.5 mm. Microstimulation provides critical evidence that they overlap. The words ‘discrete’ and ‘mosaic’ therefore have no place in the description of the fine-grained structure of cortico-motoneuronal output in the baboon. To discharge every cell in a colony simultaneously it is necessary to employ surface stimulation. Maximum output can be measured only by intracellular recording from the target motoneuron.