Arpin David J, Gehringer James E, Wilson Tony W, Kurz Max J
Department of Physical Therapy, Munroe-Meyer Institute, University of Nebraska Medical Center, Omaha, Nebraska.
Center for Magnetoencephalography, University of Nebraska Medical Center, Omaha, Nebraska; and.
J Neurophysiol. 2017 Oct 1;118(4):2052-2058. doi: 10.1152/jn.00260.2017. Epub 2017 Jul 19.
When identical stimuli are presented in rapid temporal succession, neural responses to the second stimulation are often weaker than those observed for the first. This phenomenon is termed sensory gating and is believed to be an adaptive feature that helps prevent higher-order cortical centers from being flooded with unnecessary information. Recently, sensory gating in the somatosensory system has been linked to deficits in tactile discrimination. Additionally, studies have linked poor tactile discrimination with impaired walking and balance in individuals with multiple sclerosis (MS). In this study, we examine the neural basis of somatosensory gating in patients with MS and healthy controls and assess the relationship between somatosensory gating and walking performance. We used magnetoencephalography to record neural responses to paired-pulse electrical stimulation applied to the right posterior tibial nerve. All participants also walked across a digital mat, which recorded their spatiotemporal gait kinematics. Our results showed the amplitude of the response to the second stimulation was sharply reduced only in controls, resulting in a significantly reduced somatosensory gating in the patients with MS. No group differences were observed in the amplitude of the response to the first stimulation nor the latency of the neural response to either the first or second stimulation. Interestingly, the altered somatosensory gating responses were correlated with aberrant spatiotemporal gait kinematics in the patients with MS. These results suggest that inhibitory GABA circuits may be altered in patients with MS, which impacts somatosensory gating and contributes to the motor performance deficits seen in these patients. We aimed to determine whether somatosensory gating in patients with multiple sclerosis (MS) differed compared with healthy controls and whether a relationship exists between somatosensory gating and walking performance. We found reduced somatosensory gating responses in patients with MS, and these altered somatosensory gating responses were correlated with the mobility impairments. These novel findings show that somatosensory gating is impaired in patients with MS and is related to the mobility impairments seen in these patients.
当相同的刺激在快速的时间序列中呈现时，对第二次刺激的神经反应通常比对第一次刺激观察到的反应更弱。这种现象被称为感觉门控，被认为是一种适应性特征，有助于防止高阶皮质中枢被不必要的信息淹没。最近，体感系统中的感觉门控与触觉辨别缺陷有关。此外，研究将触觉辨别能力差与多发性硬化症（MS）患者的行走和平衡受损联系起来。在本研究中，我们检查了MS患者和健康对照者体感门控的神经基础，并评估了体感门控与行走表现之间的关系。我们使用脑磁图记录对施加于右胫后神经的成对脉冲电刺激的神经反应。所有参与者还走过一个数字垫子，该垫子记录了他们的时空步态运动学。我们的结果表明，仅在对照组中，对第二次刺激的反应幅度急剧降低，导致MS患者的体感门控显著降低。在对第一次刺激的反应幅度以及对第一次或第二次刺激的神经反应潜伏期方面，未观察到组间差异。有趣的是，MS患者体感门控反应的改变与异常的时空步态运动学相关。这些结果表明，MS患者的抑制性GABA回路可能发生了改变，这影响了体感门控，并导致了这些患者出现运动表现缺陷。我们旨在确定多发性硬化症（MS）患者的体感门控与健康对照者相比是否不同，以及体感门控与行走表现之间是否存在关系。我们发现MS患者的体感门控反应降低，并且这些改变的体感门控反应与运动障碍相关。这些新发现表明，MS患者的体感门控受损，并且与这些患者出现的运动障碍有关。
