Electrical Stimulation of Cortical Motor Output

描述（由申请人提供）：Graziano等人（2002a）最近证明，与正常运动的持续时间相匹配，对皮层运动区域进行长时间（500 ms）的重复性颅内微刺激（RL-ICMS），会产生自然的手臂运动，最终手位于个人空间的不同部位，这取决于受刺激的皮层亚区。三个子区域被确定为产生不同特征的运动。初级运动皮层（M1）的RL-ICMS诱发了以手位于猴胸前中央空间结束的运动，并形成了适合操作物体的各种手指姿势。另据报道，刺激引起的肌电图活动模式依赖于手臂姿势，并可根据初始姿势从兴奋到抑制转换。这些发现被认为与手到达相同的最终位置是一致的，与最初的起始位置无关。最近，Graziano等人（2004）报道，刺激诱发的输出效应也高度依赖于关节角度。这些结果是显著的，并提出了一个新的观点额叶运动功能。RL-ICMS被认为是参与自然的、有目的的运动的功能性神经基质。在这个应用中，我们将使用刺激触发的肌电图平均，并将重点放在M1皮层上，以研究RL-ICMS的一些发现，并测试对观察到的发现的可能的替代解释。提出了严格测试的四个具体目标：1)肌电图反应在多大程度上依赖于肢体姿势和关节角度；2)RL-ICMS观察到的自然反应可以通过每个关节的特定肌肉组的持续、强直协同激活来解释，这些肌肉组只是达到最终的平衡位置；3) RL-ICMS激活肌肉的程度可以根据M1肌肉图的详细知识和通过与ICMS相关的这些肌肉表征传播兴奋的模式来解释。

DESCRIPTION (provided by applicant): Graziano et al. (2002a) recently demonstrated that applying repetitive intracranial microstimulation (RL-ICMS) to cortical motor areas for long durations (500 ms), matching the duration of normal movements, produces natural appearing arm movements ending with the hand positioned in different parts of extrapersonal space, depending on the cortical subregion stimulated. Three subregions were identified as producing movements with different characteristics. RL-ICMS of primary motor cortex (M1) evoked movements ending with the hand positioned in central space immediately in front of the monkey's chest and the formation of various postures of the digits appropriate for object manipulation. It was also reported that the pattern of EMG activity from stimulation was arm posture dependent and could switch from excitation to inhibition depending on initial posture. These findings were viewed as consistent with the hand reaching the same final position independent of the initial starting position. More recently, Graziano et al. (2004), reported that stimulus evoked output effects were also highly joint angle dependent. These results are remarkable and suggest a novel view of frontal lobe motor function. RL-ICMS was viewed as engaging functional neural substrates for natural, purposeful movements. In this application we will use stimulus triggered averaging of EMG and focus on M1 cortex to investigate some of the findings from RL-ICMS and to test possible alternative explanations for the findings observed. Four specific aims are proposed to rigorously test: 1) the extent to which EMG responses are limb posture and joint angle dependent, 2) the possibility that natural appearing responses observed with RL-ICMS can be explained by sustained, tonic coactivation of a particular set of muscles at each joint that simply achieve a final equilibrium position, and 3) the extent to which muscles activated with RL-ICMS can be explained based on detailed knowledge of M1 muscle maps and the pattern of spread of excitation through these muscle representations associated with ICMS.