Standardization of H-reflex analyses

Brinkworth, Russell S. A.; Tuncer, Meltem; Tucker, Kylie; Jaberzadeh, Shapour; Türker, Kemal S.

doi:10.1016/j.jneumeth.2006.11.020

Cited by 49 publications

(38 citation statements)

References 35 publications

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“…To account for physiological differences between motor axons across subjects (Brinkworth, Tuncer, Tucker, Jaberzadeh, & Türker, 2007), all stimulation intensities were normalized to the minimum stimulus intensity required to obtain an M-wave (M-wave threshold; MT). The H-reflex was also plotted against the M-wave (% of the M max ) in order to establish whether a shift to the right was present in the H-reflex/M-wave recruitment curves.…”

Section: Discussionmentioning

confidence: 99%

Soleus H-Reflex Gain, Threshold, and Amplitude as Function of Body Posture and Load in Spinal Cord Intact and Injured Subjects

Knikou¹,

Angeli²,

Ferreira³

et al. 2009

International Journal of Neuroscience

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In this study, we established parameters of the soleus H-reflex excitability in response to changes of posture and load in 8 chronic spinal cord injured (SCI) and 10 spinal-intact subjects. The soleus H-reflex recruitment curve was established in all subjects while they were supine, seated, and standing on a stable treadmill. During standing, body weight support (BWS) was provided via an upper body harness and ranged in SCI subjects from 20%-50% and in spinal-intact subjects was set at 0% and 50%. Stimuli corresponding to the H-threshold (H(th)), maximal H-reflex amplitude (H(max)), and 50% of H(max) as well as the reflex gain were estimated based on a sigmoid function of the ascending limb of the soleus H-reflex recruitment curve. The soleus H-reflex gain, H(max) amplitude, and stimuli corresponding to H(th), 50% of H(max), and H(max) were increased in SCI subjects regardless of the body position and loading. Further, the reflex gain was not modulated appropriately during conditions of weight bearing in SCI subjects. Impaired spinal reflex excitability in SCI subjects is accompanied by changes of the H-reflex recruitment curve parameters regardless of presence or absence of body loading.

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Section: Discussionmentioning

confidence: 99%

Soleus H-Reflex Gain, Threshold, and Amplitude as Function of Body Posture and Load in Spinal Cord Intact and Injured Subjects

Knikou¹,

Angeli²,

Ferreira³

et al. 2009

International Journal of Neuroscience

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“…The soleus H-reflex and M-wave sizes recorded at varying stimulation intensities were normalized to the associated M max to counteract for differences of muscle geometry across subjects (Pierrot-Deseilligny and Burke 2012). Then, a sigmoid fit to the full soleus M-wave recruitment curve was applied (Klimstra and Zehr 2008; Brinkworth et al 2007). The stimulation intensity value corresponding to 50 % of M max , derived from the sigmoid fit, was then used to normalize the stimulation intensities that the H-reflexes were evoked.…”

Section: Methodsmentioning

confidence: 99%

Locomotor training modifies soleus monosynaptic motoneuron responses in human spinal cord injury

2014

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The objective of this study was to assess changes in monosynaptic motoneuron responses to stimulation of Ia afferents after locomotor training in individuals with chronic spinal cord injury (SCI). We hypothesized that locomotor training modifies the amplitude of the soleus monosynaptic motoneuron responses in a body position-dependent manner. Fifteen individuals with chronic clinical motor complete or incomplete SCI received an average of 45 locomotor training sessions. The soleus H-reflex and M-wave recruitment curves were assembled using data collected in both the right and left legs, with subjects seated and standing, before and after training. The soleus H-reflexes and M-waves, measured as peak-to-peak amplitudes, were normalized to the maximal M-wave (Mmax). Stimulation intensities were normalized to 50 % Mmax stimulus intensity. A sigmoid function was also fitted to the normalized soleus H-reflexes on the ascending limb of the recruitment curve. After training, soleus H-reflex excitability was increased in both legs in AIS C subjects, and remained unchanged in AIS A-B and AIS D subjects during standing. When subjects were seated, soleus H-reflex excitability was decreased after training in many AIS C and D subjects. Changes in reflex excitability coincided with changes in stimulation intensities at H-threshold, 50 % maximal H-reflex, and at maximal H-reflex, while an interaction between leg side and AIS scale for the H-reflex slope was also found. Adaptations of the intrinsic properties of soleus motoneurons and Ia afferents, the excitability profile of the soleus motoneuron pool, oligosynaptic inputs, and corticospinal inputs may all contribute to these changes. The findings of this study demonstrate that locomotor training impacts the amplitude of the monosynaptic motoneuron responses based on the demands of the motor task in people with chronic SCI.

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“…The optimal stimulation intensity to induce the H-reflex response is determined individually [27]. A common practice is to establish an M-wave and H-wave recruitment curve for a proper investigation of the H-reflex [4,16].…”

Section: Stimulation Parametersmentioning

confidence: 99%