Electrical Stimulation of Cortical Motor Output

描述(申请人提供)：Graziano等人。(2002a)最近证明，对皮质运动区进行长时间(500ms)的重复颅内微刺激(RL-ICMS)，与正常运动的持续时间相匹配，可以产生自然的手臂动作，最终将手放置在人外空间的不同部分，具体取决于刺激的皮质分区。三个亚区被确定为具有不同特征的生产运动。初级运动皮质(M1)的RL-ICMS诱发的运动结束于手直接位于猴子胸前的中央空间，并形成适合物体操作的手指的各种姿势。也有报道称，刺激产生的肌电活动模式依赖于手臂姿势，并且可以根据初始姿势从兴奋切换到抑制。这些发现被认为与手到达相同的最终位置是一致的，而与初始开始位置无关。最近，Graziano等人。(2004)，报道了刺激诱发的输出效应也高度依赖于关节角度。这些结果是值得注意的，并提出了额叶运动功能的新观点。RL-ICMS被认为是进行自然、有目的运动的功能性神经基质。在这项应用中，我们将使用刺激触发的肌电平均值，并将重点放在M1皮质上，以调查RL-ICMS的一些发现，并测试对观察到的发现的可能替代解释。提出了四个具体目标来严格测试：1)肌电反应在多大程度上依赖于肢体姿势和关节角度；2)用RL-ICMS观察到的自然出现的反应可以通过每个关节上一组仅达到最终平衡位置的特定肌肉的持续、紧张性共同激活来解释的可能性；以及3)用RL-ICMS激活的肌肉可以在多大程度上基于对M1肌肉地图的详细了解以及通过这些与ICMS相关的肌肉表示来解释兴奋的传播模式。

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.