Mathew I B Debenham1, Hogun J Kang1, Stephen S Cheung2, Brian H Dalton3. 1. Sensorimotor Physiology and Integrative Neuromechanics Lab, Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia Okanagan, Kelowna, BC, Canada. 2. Department of Kinesiology, Brock University, St. Catharines, ON, Canada. 3. Sensorimotor Physiology and Integrative Neuromechanics Lab, Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia Okanagan, Kelowna, BC, Canada. brian.dalton@ubc.ca.
Abstract
PURPOSE: Foot sole cooling increases vestibular-evoked balance responses, but less is known about foot dorsum temperature alterations. The purpose was to determine whether decreasing cutaneous receptor sensitivity via foot dorsum cooling modulates the vestibular control of balance. METHODS: Eighteen participants (9 males; 9 females) stood quietly on a force plate with feet together, eyes closed, and head rotated leftward during 4, 90-s trials (2 control; 2 cooled) of continuous electrical vestibular stimulation (EVS). Icepacks placed on the dorsum of both feet for 15 min induced cooling and remained throughout the EVS trials. Monofilament testing was performed at multiple locations before and after cooling to determine tactile detection thresholds. T-type thermocouples monitored skin temperature over the tibialis anterior, soleus, foot dorsum and arch of the right leg. Vestibular-evoked balance responses were characterized using time (cumulant density) and frequency (coherence and gain) domain analyses to determine the relationship between the EVS input and motor output (anteroposterior force-AP force; right medial gastrocnemius electromyography-MG EMG). RESULTS: Skin temperature of the foot dorsum and arch decreased ~ 70 and 15%, respectively during cooling (p < 0.05), but was unaltered at other locations (p ≥ 0.10). Detection thresholds for the foot dorsum increased following cooling (p < 0.05). Surprisingly, cooling reduced EVS-AP force and EVS-MG EMG coherence and gain at multiple frequencies, and peak-to-peak amplitude compared to control (p < 0.05). CONCLUSION: Our results indicate that vestibular-driven balance responses are reduced following foot dorsum cooling, likely owing to alterations in cutaneous mechanoreceptor sensitivity and subsequent alterations in the transformation of vestibular cues for balance control.
PURPOSE: Foot sole cooling increases vestibular-evoked balance responses, but less is known about foot dorsum temperature alterations. The purpose was to determine whether decreasing cutaneous receptor sensitivity via foot dorsum cooling modulates the vestibular control of balance. METHODS: Eighteen participants (9 males; 9 females) stood quietly on a force plate with feet together, eyes closed, and head rotated leftward during 4, 90-s trials (2 control; 2 cooled) of continuous electrical vestibular stimulation (EVS). Icepacks placed on the dorsum of both feet for 15 min induced cooling and remained throughout the EVS trials. Monofilament testing was performed at multiple locations before and after cooling to determine tactile detection thresholds. T-type thermocouples monitored skin temperature over the tibialis anterior, soleus, foot dorsum and arch of the right leg. Vestibular-evoked balance responses were characterized using time (cumulant density) and frequency (coherence and gain) domain analyses to determine the relationship between the EVS input and motor output (anteroposterior force-AP force; right medial gastrocnemius electromyography-MG EMG). RESULTS: Skin temperature of the foot dorsum and arch decreased ~ 70 and 15%, respectively during cooling (p < 0.05), but was unaltered at other locations (p ≥ 0.10). Detection thresholds for the foot dorsum increased following cooling (p < 0.05). Surprisingly, cooling reduced EVS-AP force and EVS-MG EMG coherence and gain at multiple frequencies, and peak-to-peak amplitude compared to control (p < 0.05). CONCLUSION: Our results indicate that vestibular-driven balance responses are reduced following foot dorsum cooling, likely owing to alterations in cutaneous mechanoreceptor sensitivity and subsequent alterations in the transformation of vestibular cues for balance control.
Authors: Christopher J Dakin; Billy L Luu; Kees van den Doel; John Timothy Inglis; Jean-Sébastien Blouin Journal: J Neurophysiol Date: 2009-12-23 Impact factor: 2.714
Authors: Brian H Dalton; Jean-Sébastien Blouin; Matti D Allen; Charles L Rice; J Timothy Inglis Journal: Exp Gerontol Date: 2014-10-14 Impact factor: 4.032