Weiss D S, Keller A
Department of Anatomy and Cell Biology, Uniformed Services, University of Health Sciences, Bethesda, Maryland 20814.
Cereb Cortex. 1994 Mar-Apr;4(2):205-14. doi: 10.1093/cercor/4.2.205.
The organization of intrinsic connections in rat motor cortex was studied by combining microstimulation and tract-tracing techniques. Maps of forelimb and vibrissal movements were constructed from the distribution of cortical sites from which movements were evoked in response to intracortical microstimulation. Then, a single injection of a fluorescent dextran was placed into either a vibrissal or a wrist representation zone, or into a region bordering these zones, resulting in anterograde labeling of long intrinsic, horizontal axons. Following injection into the vibrissal area, axons were largely restricted to the whisker representation zone and to the border region with the forelimb representation. Injections into a wrist zone labeled projections largely restricted to the forelimb area and to the border with the vibrissal area. Injections into a border region labeled dense projections throughout most of the forelimb and vibrissal areas. These findings indicate that intrinsic axon collaterals in the motor cortex form specific and extensive connections among representation zones related to movements of the same body part. These connections may be involved in the coordination of activity in different representation zones for the execution of complex movement patterns. The projection of axon collaterals into border regions may be the anatomical substrate for the rapid reorganization of motor cortical maps that occurs following various experimental manipulations.
通过结合微刺激和示踪技术，对大鼠运动皮层的内在连接组织进行了研究。根据皮层部位的分布构建了前肢和触须运动图谱，这些部位在响应皮层内微刺激时会诱发运动。然后，将单次注射的荧光葡聚糖注入触须或腕部代表区，或注入与这些区域相邻的区域，从而对长的内在水平轴突进行顺行标记。注入触须区域后，轴突主要局限于触须代表区以及与前肢代表区的边界区域。注入腕部区域的标记投射主要局限于前肢区域以及与触须区域的边界。注入边界区域的标记在大部分前肢和触须区域形成密集投射。这些发现表明，运动皮层中的内在轴突侧支在与同一身体部位运动相关的代表区之间形成了特定且广泛的连接。这些连接可能参与了不同代表区活动的协调，以执行复杂的运动模式。轴突侧支投射到边界区域可能是各种实验操作后运动皮层图谱快速重组的解剖学基础。
