Capaday Charles
Brain and Movement Laboratory, Department of Bioengineering, McGill University, Montreal, QC, Canada.
Department of Health and Human Physiology, The University of Iowa, Iowa City, IA, United States.
Front Comput Neurosci. 2022 Aug 11;16:851485. doi: 10.3389/fncom.2022.851485. eCollection 2022.
The effects of intracortical microstimulation (ICMS) parameters on the evoked electromyographic (EMG) responses and resulting limb movement were investigated. In ketamine-anesthetized cats, paw movement kinematics in 3D and EMG activity from 8 to 12 forelimb muscles evoked by ICMS applied to the forelimb area of the cat motor cortex (MCx) were recorded. The EMG responses evoked by ICMS were also compared to those evoked by focal ictal bursts induced by the iontophoretic ejection of the GABA receptor antagonist bicuculline methochloride (BIC) at the same cortical point. The effects of different initial limb starting positions on movement trajectories resulting from long-duration ICMS were also studied. The ICMS duration did not affect the evoked muscle activation pattern (MAP). Short (50 ms) and long (500 ms) stimulus trains activated the same muscles in the same proportions. MAPs could, however, be modified by gradually increasing the stimulus intensity. MAPs evoked by focal ictal bursts were also highly correlated with those obtained by ICMS at the same cortical point. Varying the initial position of the forelimb did not change the MAPs evoked from a cortical point. Consequently, the evoked movements reached nearly the same final end point and posture, with variability. However, the movement trajectories were quite different depending on the initial limb configuration and starting position of the paw. The evoked movement trajectory was most natural when the forelimb lay pendant ~ perpendicular to the ground (i.e., in equilibrium with the gravitational force). From other starting positions, the movements did not appear natural. These observations demonstrate that while the output of the cortical point evokes a seemingly coordinated limb movement from a rest position, it does not specify a particular movement direction or a controlled trajectory from other initial positions.
研究了皮层内微刺激（ICMS）参数对诱发肌电图（EMG）反应及由此产生的肢体运动的影响。在氯胺酮麻醉的猫中，记录了应用于猫运动皮层（MCx）前肢区域的ICMS诱发的三维爪部运动运动学以及8至12块前肢肌肉的EMG活动。还将ICMS诱发的EMG反应与在同一皮层点通过离子电渗法注射GABA受体拮抗剂氯化甲基荷包牡丹碱（BIC）诱发的局灶性发作性爆发所诱发的反应进行了比较。还研究了不同的初始肢体起始位置对长时间ICMS产生的运动轨迹的影响。ICMS持续时间不影响诱发的肌肉激活模式（MAP）。短（50毫秒）和长（500毫秒）刺激序列以相同比例激活相同的肌肉。然而，MAP可以通过逐渐增加刺激强度来改变。局灶性发作性爆发诱发的MAP也与在同一皮层点通过ICMS获得的MAP高度相关。改变前肢的初始位置不会改变从皮层点诱发的MAP。因此，诱发的运动几乎达到相同的最终终点和姿势，但存在变异性。然而，运动轨迹根据爪的初始肢体构型和起始位置而有很大不同。当前肢垂悬 ~ 垂直于地面（即，与重力平衡）时，诱发的运动轨迹最自然。从其他起始位置开始，运动看起来不自然。这些观察结果表明，虽然皮层点的输出从静止位置诱发看似协调的肢体运动，但它并未指定特定的运动方向或从其他初始位置的受控轨迹。
