Guggenberger Robert, Raco Valerio, Gharabaghi Alireza
Institute for Neuromodulation and Neurotechnology, Department of Neurosurgery and Neurotechnology, University of Tüebingen, Tüebingen, Germany.
Front Bioeng Biotechnol. 2020 Oct 2;8:523866. doi: 10.3389/fbioe.2020.523866. eCollection 2020.
Afferent somatosensory information plays a crucial role in modulating efferent motor output. A better understanding of this sensorimotor interplay may inform the design of neurorehabilitation interfaces. Current neurotechnological approaches that address motor restoration after trauma or stroke combine motor imagery (MI) and contingent somatosensory feedback, e.g., via peripheral stimulation, to induce corticospinal reorganization. These interventions may, however, change the motor output already at the spinal level dependent on alterations of the afferent input. Neuromuscular electrical stimulation (NMES) was combined with measurements of wrist deflection using a kinematic glove during either MI or rest. We investigated 360 NMES bursts to the right forearm of 12 healthy subjects at two frequencies (30 and 100 Hz) in random order. For each frequency, stimulation was assessed at nine intensities. Measuring the induced wrist deflection across different intensities allowed us to estimate the input-output curve (IOC) of the spinal motor output. MI decreased the slope of the IOC independent of the stimulation frequency. NMES with 100 Hz vs. 30 Hz decreased the threshold of the IOC. Human-machine interfaces for neurorehabilitation that combine MI and NMES need to consider bidirectional communication and may utilize the gain modulation of spinal circuitries by applying low-intensity, high-frequency stimulation.
传入体感信息在调节传出运动输出中起着关键作用。更好地理解这种感觉运动相互作用可能会为神经康复接口的设计提供信息。当前用于创伤或中风后运动恢复的神经技术方法结合了运动想象（MI）和偶然的体感反馈，例如通过外周刺激，以诱导皮质脊髓重组。然而，这些干预可能会根据传入输入的改变，在脊髓水平就改变运动输出。在运动想象或休息期间，将神经肌肉电刺激（NMES）与使用运动手套测量手腕偏转相结合。我们以随机顺序对12名健康受试者的右前臂进行了360次NMES脉冲刺激，频率为两个（30和100赫兹）。对于每个频率，在九种强度下评估刺激。测量不同强度下诱发的手腕偏转使我们能够估计脊髓运动输出的输入-输出曲线（IOC）。运动想象降低了输入-输出曲线的斜率，与刺激频率无关。100赫兹与30赫兹相比的神经肌肉电刺激降低了输入-输出曲线的阈值。结合运动想象和神经肌肉电刺激的神经康复人机接口需要考虑双向通信，并且可以通过应用低强度、高频刺激来利用脊髓回路的增益调制。
