Keyser Johannes, Medendorp W Pieter, Selen Luc P J
Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands.
J Neurophysiol. 2017 Jul 1;118(1):84-92. doi: 10.1152/jn.00112.2017. Epub 2017 Mar 29.
When reaching for an earth-fixed object during self-rotation, the motor system should appropriately integrate vestibular signals and sensory predictions to compensate for the intervening motion and its induced inertial forces. While it is well established that this integration occurs rapidly, it is unknown whether vestibular feedback is specifically processed dependent on the behavioral goal. Here, we studied whether vestibular signals evoke fixed responses with the aim to preserve the hand trajectory in space or are processed more flexibly, correcting trajectories only in task-relevant spatial dimensions. We used galvanic vestibular stimulation to perturb reaching movements toward a narrow or a wide target. Results show that the same vestibular stimulation led to smaller trajectory corrections to the wide than the narrow target. We interpret this reduced compensation as a task-dependent modulation of vestibular feedback responses, tuned to minimally intervene with the task-irrelevant dimension of the reach. These task-dependent vestibular feedback corrections are in accordance with a central prediction of optimal feedback control theory and mirror the sophistication seen in feedback responses to mechanical and visual perturbations of the upper limb. Correcting limb movements for external perturbations is a hallmark of flexible sensorimotor behavior. While visual and mechanical perturbations are corrected in a task-dependent manner, it is unclear whether a vestibular perturbation, naturally arising when the body moves, is selectively processed in reach control. We show, using galvanic vestibular stimulation, that reach corrections to vestibular perturbations are task dependent, consistent with a prediction of optimal feedback control theory.
在自我旋转过程中伸手去够一个固定在地面的物体时，运动系统应适当地整合前庭信号和感觉预测，以补偿中间的运动及其产生的惯性力。虽然已经明确这种整合会迅速发生，但尚不清楚前庭反馈是否会根据行为目标进行特异性处理。在这里，我们研究了前庭信号是否会引发固定反应以在空间中保持手部轨迹，或者是否会更灵活地处理，仅在与任务相关的空间维度上校正轨迹。我们使用电流前庭刺激来干扰朝向窄目标或宽目标的伸手动作。结果表明，相同的前庭刺激对宽目标的轨迹校正比对窄目标的小。我们将这种减少的补偿解释为前庭反馈反应的任务依赖性调制，调整为最小程度地干预伸手动作中与任务无关的维度。这些任务依赖性前庭反馈校正符合最优反馈控制理论的核心预测，并且反映了在上肢机械和视觉扰动的反馈反应中所看到的复杂性。针对外部扰动校正肢体运动是灵活的感觉运动行为的一个标志。虽然视觉和机械扰动是以任务依赖的方式校正的，但尚不清楚身体移动时自然产生的前庭扰动在伸手控制中是否会被选择性处理。我们使用电流前庭刺激表明，对前庭扰动的伸手校正依赖于任务，这与最优反馈控制理论的预测一致。
