Reliability and laterality of the soleus H-reflex following galvanic vestibular stimulation in healthy individuals

Relationships between changes in lateral vestibulospinal tract excitability and postural control by dynamic balance intervention in healthy individuals: A preliminary study

“…No significant interaction was observed between group and time for GVSH [ F (1, 26) = 0.666, p = 0.442], COP area [ F (1, 26) = 3.50, p = 0.073], COP velocity [ F (1, 26) = 0.888, p = 0.355], x axis α [ F (1, 26) = 0.930, p = 0.3439], or y axis α [ F (1, 26) = 0.030, p = 0.865] nor was there a significant main effect of group [GVSH: F (1, 26) = 0.102, p = 0.752; COP area: F (1, 26) = 0.095, p = 0.760; COP velocity: F (1, 26) = 0.258, p = 0.620; x axis α : F (1, 26) = 0.023, p = 0.881; y axis α : F (1,26) = 2.982, p = 0.096] or time [GVSH: F (1, 26) = 0.036, p = 0.851; COP area: F (1, 26) = 0.736, p = 0.399; COP velocity: F (1, 26) = 2.786, p = 0.107; x axis α : F (1, 26) = 0.021, p = 0.887; y axis α : F (1, 26) = 1.555, p = 0.224], as illustrated in Figure 3 . However, 47.1% (8/17) of subjects in the dynamic balance group and 0% (0/11) in the control group displayed a change in GVSH greater than 11%, the MDC established in a previous study ( Nakamura et al, 2021 ).…”

“…Second, GVSH was measured only with the right foot in the prone position. Although it has been reported that there is no difference in GVSH between right and left in healthy participants ( Nakamura et al, 2021 ), it is known that there is a relationship between the left and right ratio and the static standing position, and adaptation to the intervention may differ between the left and right. In addition, to examine the relationship with posture control, it is possible that the measurement in the sitting position ( Tanaka et al, 2021 ), an antigravity limb position, is more sensitive for observing the changes.…”

“…The peak-to-peak amplitudes of the H-reflex were computed offline. The GVSH was calculated using the following formula: (conditoned H reflex ampulitued [mV] ÷ unconditoned H reflex ampulitued [ mV ]−1)×100%) ( Lowrey and Bent, 2009 ; Nakamura et al, 2021 ). The change rate of the H-reflex by the GVS reflected LVST excitability ( Horak et al, 1992 ).…”

“…The facilitation ratio of the H-reflex of the soleus muscle, as conditioned by cathode GVS (GVSH), serves as a reflection of LVST excitability. We have previously validated the optimal GVS stimulus intensity for the measurement of GVSH ( Okada et al, 2018 ) and demonstrated that the method exhibits high test-retest reliability, with a minimum detectable change (MDC) in GVSH of 11.0% ( Nakamura et al, 2021 ). Furthermore, we have observed that GVSH increases in antigravity postures, providing evidence of LVST function ( Tanaka et al, 2021 ).…”

Vestibulo-Ocular Reflex Is Modulated by Noisy Galvanic Vestibular Stimulation

“…The stimulation conditions of nGVS were not known to the participants or assessors for vHIT. Before examination, we tested inducing body sway to the anodal side ( 22 ) by a 2.5-mA square wave pulse (spGVS) ( 23 , 24 ) with 200 ms duration ( 25 , 26 ) while participants maintained upright standing with their head facing forward ( 26 ), eyes closed, and feet together ( 25 , 27 ). This test was conducted to determine whether they were responders to GVS, as per previously conducted methodology ( 19 ).…”