Richardson Andrew G, Lassi-Tucci Glenda, Padoa-Schioppa Camillo, Bizzi Emilio
Division of Health Sciences and Technology, Massachusetts Institute of Technology, 43 Vassar Street, Cambridge, MA 02139, USA.
J Neurophysiol. 2008 Mar;99(3):1253-66. doi: 10.1152/jn.01096.2007. Epub 2008 Jan 23.
Neurons in the cingulate motor areas (CMA) have been shown to be involved in many aspects of sensorimotor behavior, although their role in motor learning has received less attention. Here, we recorded single-cell activity in the CMA of monkeys while they adapted reaching movements to different dynamic environments. Specifically, we analyzed CMA activity during normal reaching to visual targets and during reaching in the presence of an applied velocity-dependent force field. We found that the cingulate neuronal activity was modulated during each phase of the task and in response to the applied forces. The neurons' involvement in the visuomotor transformation was influenced by their rostrocaudal location in the cingulate sulcus. Rostral CMA (CMAr) neurons were modulated by the visual instruction to a greater extent than caudal CMA (CMAc) neurons. In contrast, CMAc neurons had a greater amount of phasic and directionally tuned activity during movement than CMAr cells. Furthermore, compared with CMAr cells, the movement-related activity of CMAc cells was more frequently modulated by the applied force fields. The magnitude of the force-field-related neuronal response scaled with the amount of perturbation in each reaching direction. However, contrary to previous results from other cortical motor areas, force-field adaptation was not correlated with a shift in directional tuning of the CMA population. Based on these results, we suggest that although the CMA is clearly sensitive to applied forces, it is less involved in generating anticipatory responses to predictable forces than other cortical motor areas.
扣带回运动区（CMA）的神经元已被证明参与感觉运动行为的许多方面，尽管它们在运动学习中的作用较少受到关注。在这里，我们记录了猴子在将伸手动作适应不同动态环境时CMA中的单细胞活动。具体而言，我们分析了正常伸手够视觉目标时以及在存在施加的速度依赖性力场的情况下伸手时的CMA活动。我们发现，扣带回神经元活动在任务的每个阶段以及对施加的力的反应中都受到调制。神经元对视觉运动转换的参与受其在扣带回沟中的前后位置影响。与尾侧CMA（CMAc）神经元相比，吻侧CMA（CMAr）神经元在更大程度上受到视觉指令的调制。相反，CMAc神经元在运动过程中的相位性和方向调谐活动比CMAr细胞更多。此外，与CMAr细胞相比，CMAc细胞的运动相关活动更频繁地受到施加的力场的调制。力场相关神经元反应的大小与每个伸手方向上的扰动程度成比例。然而，与其他皮质运动区先前的结果相反，力场适应与CMA群体方向调谐的变化无关。基于这些结果，我们认为，尽管CMA对施加的力明显敏感，但与其他皮质运动区相比，它在产生对可预测力的预期反应方面的参与较少。
