DOI: 10.34945/f5m88z
title: H-reflex modulation from sensory conditioning in non injured female and male human participants

description: STUDY PURPOSE: Sensory signals travelling into the spinal cord, and the control of those sensory signals, are essential for human movement. For many years it was believed that sensory signals, specifically action potentials travelling along Ia afferents, were suppressed by GABAA receptor mediated primary afferent depolarization (PAD). Recent findings in animals and humans show a faciliatory role for PAD in Ia afferent conduction, putting into question previous reports showing that conditioning inputs that putatively evoke PAD suppress subsequent H-reflex (Ia – motoneuron) activations. In this dataset, and the accompanying paper, we present data used to examine the control of sensory signals by GABAergic inputs along the Ia-motoneuron pathway in humans. DATA COLLECTED: Our sample compromised of 28 adult (age 20-58 years) human participants (11 male). Thirteen of the participants also participated in the related study (dataset 811), subject IDs match for overlapping participants. The Ia – motoneuron pathway was measured by percutaneously stimulating the tibial nerve in the popliteal fossa to activate a soleus H-reflex. The peak-peak amplitude of the soleus H-reflex was measured before (test) and after (cond) a conditioning stimulation to putatively activate GABAergic networks in the spinal cord and primary afferent depolarization (PAD) in the test (soleus) Ia afferents. Specifically, mechanical vibration of the tibialis anterior tendon at the ankle (3 pulses, 10 Hz) or percutaneous stimulation of the common fibular nerve (CFN; 1.0 or 1.5 x motor threshold, 200 Hz, 10 ms; near the fibular head on the ipsilateral leg) was applied at an interstimulus interval (ISI) before evoking the soleus H-reflex. The ISI (ISI_Vib; ISI_CFN) and average percent change of the peak-peak amplitude of the conditioned soleus H-reflex at various interstimulus intervals for each participant is presented in the data set (Vib_Hreflex; CFN_1.0xMT_Hreflex; CFN_1.5xMT_Hreflex; CFN_facilitation_Hreflex). Soleus single motor units and ongoing EMG were measured in response to the conditioning stimulation (vibration or CFN stimulation) applied alone to isolate the postsynaptic effects of the conditioning stimulation on the soleus motoneurons. Specifically, the average firing rate of the soleus single motor units (taken from the peristimulus frequencygram [PSF]; PSF_Vib; PSF_CFN_1.0xMT; PSF_CFN_1.5xMT) or amplitude of the ongoing EMG (EMG_Vib; EMG_CFN_1.0xMT; EMG_CFN_1.5xMT) over many trials was averaged into 10 ms bins (Time_of_bin_Vib; Time_of_bin_CFN) for each participant. The average early (100-300 ms after the CFN stimulation) soleus motor unit firing rate was also measured for each participant (Early_MU_area). The number of units fired per 10 ms bin from the PSF were also measured using a peristimulus time histogram (PSTH; PSTH_Vib; PSTH_CFN_1.0xMT; PSTH_CFN_1.5xMT). As a measure of post-activation depression, rate dependent depression (RDD) of the soleus H-reflex was compared to the longer CFN conditioning trials by repetitively activating (stimulating the tibial nerve in the popliteal fossa) the same soleus H-reflex at the same interstimulus intervals (500-2500ms). The average percent change of the soleus H-reflex in response to repetitive activation (by comparing the first H-reflex in a trial to the average of the next 7 H-reflexes) is presented in the data set (RDD_percent_change) for each ISI (ISI_CFN). This data is also presented showing the percent change of the soleus H-reflex in response to repetitive activations (RDD_2500_change_Hreflex; RDD_2000_change_Hreflex; RDD_1500_change_Hreflex; RDD_1000_change_Hreflex; RDD_500_change_Hreflex) and CFN conditioning stimulation (CFN_2500_change_Hreflex; CFN_2000_change_Hreflex; CFN_1500_change_Hreflex; CFN_1000_change_Hreflex; CFN_500_change_Hreflex) at each ISI (500-2500 ms) and for each H-reflex number in a trial (Hreflex_number). DATA USAGE NOTES: