Waters R S, Samulack D D, Dykes R W, McKinley P A
Department of Anatomy and Neurobiology, College of Medicine, University of Tennessee-Memphis 38163.
Somatosens Mot Res. 1990;7(4):485-514. doi: 10.3109/08990229009144721.
(1) The fine details of the motor organization of the forelimb, face, and tongue representation of the baboon (Papio h. anubis) primary motor cortex were studied in four adult animals, using intracortical microstimulation (ICMS). (2) A total of 293 electrode penetrations were made. ICMS was delivered to 10,052 sites, and of these, 6,186 sites were verified to have been located within the grey matter. Motor effects were evoked from 30% of these sites. (3) The baboon motor cortex is confined, in large part, to the cortical tissue lying along the anterior bank of the central sulcus. When the electrode penetrations were confined to the precentral gyrus, few sites were capable of evoking movement when stimulated by currents of 40 microA or less. (4) The details of the motor maps varied among the four animals; nonetheless, a general topographic organization existed, with the tongue musculature being represented most laterally, followed by a medial progression of the face, digits, wrist, forearm, and shoulder. Within the representation of a given body part, the muscles were organized as a mosaic, wherein the same muscle was multiply represented. (5) A zone of unresponsive cortex was observed to lie consistently between the face and forelimb representation in all four animals. Repeated electrode penetrations within the unresponsive zone failed to elicit muscle contractions even with stimulating currents as high as 80 microA. (6) Our results suggest that the baboon motor cortex is topographically organized; however, embedded within this overall pattern lies a fine-grained mosaic incorporating multiple representations of the same muscle.
(1) 利用皮质内微刺激（ICMS）技术，对4只成年狒狒（埃及狒狒）初级运动皮层中前肢、面部和舌部代表区的精细运动组织细节进行了研究。(2) 总共进行了293次电极穿刺。向10052个位点施加了ICMS，其中6186个位点被证实位于灰质内。从这些位点中的30%诱发了运动效应。(3) 狒狒的运动皮层在很大程度上局限于沿中央沟前缘的皮质组织。当电极穿刺局限于中央前回时，用40微安或更小的电流刺激时，很少有位点能诱发运动。(4) 这四只动物的运动图谱细节各不相同；尽管如此，仍存在一种一般的拓扑组织，舌部肌肉组织在最外侧代表，随后是面部、手指、手腕、前臂和肩部向内侧依次排列。在给定身体部位的代表区内，肌肉呈镶嵌式组织，同一肌肉有多处代表。(5) 在所有四只动物中，均观察到在面部和前肢代表区之间始终存在一个无反应皮质区。即使使用高达80微安的刺激电流，在无反应区内重复进行电极穿刺也未能诱发肌肉收缩。(6) 我们的结果表明，狒狒的运动皮层是按拓扑方式组织的；然而，在这一整体模式中嵌入了一个精细的镶嵌式结构，其中包含同一肌肉的多个代表区。
