Controlling an identical movement with position or force feedback results in different neural activation and motor behavior. This protocol describes how to investigate behavioral changes by looking at neuromuscular fatigue and how to evaluate motor cortical (inhibitory) activity using subthreshold TMS with respect to the interpretation of augmented feedback.
During motor behaviour, humans interact with the environment by for example manipulating objects and this is only possible because sensory feedback is constantly integrated into the central nervous system and these sensory inputs need to be weighted in order meet the task specific goals. Additional feedback presented as augmented feedback was shown to have an impact on motor control and motor learning. A number of studies investigated whether force or position feedback has an influence on motor control and neural activation. However, as in the previous studies the presentation of the force and position feedback was always identical, a recent study assessed whether not only the content but also the interpretation of the feedback has an influence on the time to fatigue of a sustained submaximal contraction and the (inhibitory) activity of the primary motor cortex using subthreshold transcranial magnetic stimulation. This paper describes one possible way to investigate the influence of the interpretation of feedback on motor behaviour by investigating the time to fatigue of submaximal sustained contractions together with the neuromuscular adaptations that can be investigated using surface EMG. Furthermore, the current protocol also describes how motor cortical (inhibitory) activity can be investigated using subthreshold TMS, a method known to act solely on the cortical level. The results show that when participants interpret the feedback as position feedback, they display a significantly shorter time to fatigue of a submaximal sustained contraction. Furthermore, subjects also displayed an increased inhibitory activity of the primary cortex when they believed to receive position feedback compared when they believed to receive force feedback. Accordingly, the results show that interpretation of feedback results in differences on a behavioural level (time to fatigue) that is also reflected in interpretation-specific differences in the amount of inhibitory M1 activity.
感官反馈是执行动作的关键。日常活动在没有本体1的几乎不可能的。此外,运动学习是由本体集成2个或皮肤感觉3的影响。健康人与完整感觉能够加权从各种感觉源所产生的感觉输入,以满足具体情况的需要4。这种感觉使称重人类具有精度高,即使感官信息的某些方面是不可靠的,甚至没有执行艰难的任务( 例如 ,在黑暗中行走或闭眼)。
此外,各种证据表明,可增强(或附加的)反馈进一步提高电动机控制和/或运动学习。增强反馈提供通过其可以添加到任务固有(感觉)从感官产生的反馈外部源的其他信息系统5,6。特别是增强反馈的电机控制和学习内容的影响是极大的兴趣,在最近几年。其中一个问题解决了人类如何控制力量和位置7,8。警方初步调查认定使用任一位置或强制加载符合反馈和分歧,持续次最大收缩疲劳时间差异( 例如,9-12)。当受试者提供力反馈,时间持续收缩乏力比较时提供位置反馈给显著更长的时间。观察到各种不同的肌肉和肢体位置和若干神经肌肉机制同样的现象,包括马达单元招募更大的速率和位置控制的收缩(综述13)中在H反射面积更大的减少。然而,在这些研究中,不仅在视觉反馈,而且物理Ç肌肉收缩的特性( 即 ,测量装置的合规性)的改变。因此,我们最近进行的一项研究不改变规定,但只增加反馈,并提供了证据的持续收缩亚最大过程中提供武力和单独位置反馈可能会导致初级运动皮层(M1)内的抑制活性的差异。这是使用已知在皮质水平14,即低于阈值的经颅磁刺激(subTMS)纯粹充当刺激技术所示。不像阈上TMS,由subTMS诱发的反应,不会被脊柱α-运动神经元和兴奋性兴奋性神经元和/或皮质细胞15-17的兴奋性,但仅通过抑制皮质内神经元的兴奋调制。这种刺激技术背后的假设机理是,它是在强度施加低于阈值,以唤起一个运动诱发电位(MEP)。它表明在具有这种类型的刺激不产生任何下行活动宫颈水平植入电极的患者,但是它主要激活初级运动皮质14,18,19内抑制性。抑制性的本激活导致正在进行的EMG活动的降低,并且可以通过相对于无刺激在试验中获得的EMG活动肌电抑制量进行定量。在这方面,我们发现,受试者在他们与试验中,力反馈提供了20相比接收到的位置反馈试验显示显著更大的抑制活性。此外,我们还发现,不仅不同的反馈方式(力与位置控制),而且反馈的诠释呈现会 对行为和神经生理学数据非常类似的效果。更具体地,当我们让参与者接收position反馈(即使它是力反馈),他们也不仅表现更短的时间疲劳,也抑制M1活动21的水平提高。使用其中总是提供相同的反馈,但用约其内容不同的信息的方法具有的优点是,任务的限制, 即,反馈的介绍,反馈的增益,或负载的顺应性是条件,以便之间相同在性能和神经活动的差异是清楚的相关中的反馈的不同解释,并且不通过不同的测试条件下偏置。因此,目前的研究调查一个的不同的解释,并且在同一反馈是否影响持续次最大收缩的持续时间,进而对主运动皮层的抑制活性的激活产生影响。
如果追加反馈的解释影响时间持续次最大收缩疲劳和初级运动皮层的神经处理本研究探讨。结果表明,只要参与者解释反馈位置反馈(相对于力反馈),时间疲劳是显著较短,运动皮层(所引起的subTMS肌电抑制量来衡量)的抑制活性越大。作为任务没有条件之间变化,目前的研究结果表明在根据反馈的源的解释力和位置的控制策略的差异。如定时28或反馈而本研究的频率29,30集中?…
The authors have nothing to disclose.
The authors have no acknowledgements.
torquemeter | LCB 130, ME-Mebsysteme, Neuendorf, Germany | Part of robotic device built for force and position recordings | |
potentiometer | type 120574, Megatron, Putzbrunn, Germany | Part of robotic device built for force and position recordings | |
EMG electrodes | Blue sensor P, Ambu, Bad Nauheim, Germany | ||
TMS coil | Magstim | ||
TMS machine | Magstim Company Ltd., Whitland, UK | ||
Recording software | Labview-Based | custom written software |