Neurology Department, Centre Hospitalier Universitaire de Toulouse, Hôpital Purpan, Toulouse, France.
Institute of Biomedical Problems, Russian Academy of Sciences, Moscow, Russia.
PLoS One. 2018 Aug 22;13(8):e0201704. doi: 10.1371/journal.pone.0201704. eCollection 2018.
Dry immersion is a ground-based experiment simulating the effects of weightlessness, and it is a model of acute symmetrical bilateral deafferentation. This exploratory study aimed to investigate the effects of three days of dry immersion (DI) on sensory thresholds and the functioning of lemniscal pathways, assessed by somatosensory evoked potentials (SEPs).
Twelve healthy male volunteers (32+/-4.8 years) participated in the study. Sensory thresholds and SEPs of the tibial nerve of both limbs were recorded before (D-1) and on the third day of dry immersion (D3).
Sensory thresholds significantly decreased on D3 (-20.75 +/-21.7%; z = -2.54; p = 0.0109 on the right side and -22.18+/-17.28%; z = -3.059; p = 0.002 on the left side). The amplitude of P40 responses did not differ between D-1 and D3. Latencies of all central responses until P30 were shortened on D3 (N21 right:-0.57+/-0.31; z = -3.06; p = 0.002; N21 left -0.83+/-0.53; z = -2.94; p = 0.003; P30 right: -1.26+/-1.42; z = -3.059; p = 0.002; P30 left: -1.11+/-1.55; z = -2.27; p = 0.02).
Three days of dry immersion can induce hyperexcitability of lemniscal pathways.
This may be explained by a change in the expression of membrane channels and/or medullar plasticity and/or hypersensitization of peripheral sensory receptors induced by this acute deafferentation. Additional studies are needed to further elucidate the mechanisms.
干浸法是一种模拟失重效应的地面实验，是急性双侧对称性去传入的模型。本探索性研究旨在探讨干浸（DI）三天对感觉阈值和体感诱发电位（SEP）评估的薄束通路功能的影响。
12 名健康男性志愿者（32+/-4.8 岁）参与了这项研究。在干浸前一天（D-1）和干浸的第三天（D3），记录了双侧胫骨神经的感觉阈值和 SEP。
感觉阈值在 D3 时显著降低（右侧为-20.75 +/-21.7%，z = -2.54，p = 0.0109；左侧为-22.18+/-17.28%，z = -3.059，p = 0.002）。P40 反应的振幅在 D-1 和 D3 之间没有差异。所有中央反应的潜伏期直到 P30 在 D3 时缩短（右侧 N21：-0.57+/-0.31，z = -3.06，p = 0.002；左侧 N21：-0.83+/-0.53，z = -2.94，p = 0.003；右侧 P30：-1.26+/-1.42，z = -3.059，p = 0.002；左侧 P30：-1.11+/-1.55，z = -2.27，p = 0.02）。
三天的干浸可以引起薄束通路的过度兴奋。
这可能是由这种急性去传入引起的膜通道表达变化和/或髓质可塑性和/或外周感觉受体超敏反应解释的。需要进一步的研究来进一步阐明机制。
