Mouchnino Laurence, Lhomond Olivia, Morant Clément, Chavet Pascale
Aix-Marseille Université, CNRS, Laboratoire de Neurosciences Cognitives, FR 3CMarseille, France.
Aix-Marseille Université, CNRS, Institut des Sciences du MouvementMarseille, France.
Front Hum Neurosci. 2017 May 10;11:220. doi: 10.3389/fnhum.2017.00220. eCollection 2017.
It is well established that somatosensory inputs to the cortex undergo an early and a later stage of processing. The later has been shown to be enhanced when the earlier transmission decreased. In this framework, mechanical factors such as the mechanical stress to which sensors are subjected when wearing a loaded vest are associated with a decrease in sensory transmission. This decrease is in turn associated with an increase in the late sensory processes originating from cortical areas. We hypothesized that unweighting the plantar sole should lead to a facilitation of the sensory transmission. To test this hypothesis, we recorded cortical somatosensory evoked potentials (SEPs) of individuals following cutaneous stimulation (by mean of an electrical stimulation of the foot sole) in different conditions of unweighting when standing still with eyes closed. To this end, the effective bodyweight (BW) was reduced from 100% BW to 40% BW. Contrary to what was expected, we found an attenuation of sensory information when the BW was unweighted to 41% which was not compensated by an increase of the late SEP component. Overall these results suggested that the attenuation of sensory transmission observed in 40 BW condition was not solely due to the absence of forces acting on the sole of the feet but rather to the current relevance of the afferent signals related to the balance constraints of the task.
众所周知，躯体感觉输入到皮层会经历早期和后期处理阶段。研究表明，当早期传输减少时，后期处理会增强。在此框架下，机械因素，如穿着负重背心时传感器所承受的机械应力，与感觉传输的减少有关。这种减少反过来又与源自皮层区域的后期感觉过程的增加有关。我们假设减轻足底重量应会促进感觉传输。为了验证这一假设，我们记录了个体在闭眼静止站立的不同失重条件下，经皮肤刺激（通过电刺激足底）后的皮层体感诱发电位（SEP）。为此，有效体重（BW）从100%BW降至40%BW。与预期相反，我们发现当体重减轻到41%时，感觉信息衰减，且后期SEP成分增加并未对此进行补偿。总体而言，这些结果表明，在40%BW条件下观察到的感觉传输衰减并非仅仅是由于作用于脚底的力缺失，而是与任务平衡约束相关的传入信号的当前相关性有关。
