Electrical Stimulation of Cortical Motor Output

描述（由申请人提供）：Graziano等人（2002 a）最近证明，对皮质运动区长时间（500 ms）施加重复颅内微刺激（RL-ICMS），与正常运动的持续时间相匹配，产生自然出现的手臂运动，最终手位于个人外空间的不同部分，取决于刺激的皮质亚区。三个次区域被确定为产生具有不同特点的运动。初级运动皮层（M1）的RL-ICMS诱发的运动结束于位于中央空间的手立即在猴子的胸部和形成的各种姿势的数字适合对象的操作。据报道，来自刺激的EMG活动模式依赖于手臂姿势，并且可以根据初始姿势从兴奋转换为抑制。这些发现被认为与手到达相同的最终位置（独立于初始起始位置）一致。最近，Graziano等人（2004年）报道刺激诱发的输出效应也高度依赖于关节角度。这些结果是显着的，并提出了一个新的观点额叶运动功能。RL-ICMS被视为参与自然，有目的的运动的功能性神经基质。在本应用中，我们将使用刺激触发的EMG平均值，并专注于M1皮层，以调查RL-ICMS的一些发现，并测试可能的替代解释所观察到的结果。提出了四个具体目标，以严格检验：1）EMG反应依赖于肢体姿势和关节角度的程度，2）用RL-ICMS观察到的自然出现的反应可以通过简单地实现最终平衡位置的每个关节处的一组特定肌肉的持续、紧张性共激活来解释的可能性，以及3）可以基于M1肌肉图的详细知识和通过与ICMS相关的这些肌肉表征的兴奋传播模式来解释用RL-ICMS激活的肌肉的程度。

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.