Nakata Hiroki, Namba Mari, Kakigi Ryusuke, Shibasaki Manabu
Department of Health Sciences, Faculty of Human Life and Environment, Nara Women's University, Nara, Japan.
Graduate School of Humanities and Sciences, Nara Women's University, Nara, Japan; and.
Am J Physiol Regul Integr Comp Physiol. 2017 Jun 1;312(6):R996-R1003. doi: 10.1152/ajpregu.00039.2017. Epub 2017 Apr 12.
We herein investigated the effects of face/head and whole body cooling during passive heat stress on human somatosensory processing recorded by somatosensory-evoked potentials (SEPs) at C4' and Fz electrodes. Fourteen healthy subjects received a median nerve stimulation at the left wrist. SEPs were recorded at normothermic baseline (Rest), when esophageal temperature had increased by ~1.2°C (heat stress: HS) during passive heating, face/head cooling during passive heating (face/head cooling: FHC), and after HS (whole body cooling: WBC). The latencies and amplitudes of P14, N20, P25, N35, P45, and N60 at C4' and P14, N18, P22, and N30 at Fz were evaluated. Latency indicated speed of the subcortical and cortical somatosensory processing, while amplitude reflected the strength of neural activity. Blood flow in the internal and common carotid arteries (ICA and CCA, respectively) and psychological comfort were recorded in each session. Increases in esophageal temperature due to HS significantly decreased the amplitude of N60, psychological comfort, and ICA blood flow in the HS session, and also shortened the latencies of SEPs (all, < 0.05). While esophageal temperature remained elevated, FHC recovered the peak amplitude of N60, psychological comfort, and ICA blood flow toward preheat baseline levels as well as WBC. However, the latencies of SEPs did not recover in the FHC and WBC sessions. These results suggest that impaired neural activity in cortical somatosensory processing during passive HS was recovered by FHC, whereas conduction velocity in the ascending somatosensory input was accelerated by increases in body temperature.
我们在此研究了被动热应激期间面部/头部和全身冷却对通过C4'和Fz电极记录的体感诱发电位（SEP）所反映的人体体感加工的影响。14名健康受试者接受了左腕正中神经刺激。在正常体温基线（静息）、被动加热期间食管温度升高约1.2°C时（热应激：HS）、被动加热期间面部/头部冷却（面部/头部冷却：FHC）以及热应激后（全身冷却：WBC）记录SEP。评估了C4'处P14、N20、P25、N35、P45和N60以及Fz处P14、N18、P22和N30的潜伏期和波幅。潜伏期表示皮质下和皮质体感加工的速度，而波幅反映神经活动的强度。每次记录颈内动脉和颈总动脉（分别为ICA和CCA）的血流以及心理舒适度。热应激导致的食管温度升高在热应激期间显著降低了N60的波幅、心理舒适度和ICA血流量，并且还缩短了SEP的潜伏期（均P<0.05）。在食管温度仍升高时，面部/头部冷却使N60的峰值波幅、心理舒适度和ICA血流量恢复到预热基线水平，全身冷却也是如此。然而，在面部/头部冷却和全身冷却期间SEP的潜伏期并未恢复。这些结果表明，被动热应激期间皮质体感加工中受损的神经活动通过面部/头部冷却得以恢复，而体感传入的传导速度则因体温升高而加快。
