Changes in H-Reflex Recruitment After Trans-Spinal Direct Current Stimulation With Multiple Electrode Configurations.

Area of Science:

• Neuroscience
• Rehabilitation Medicine
• Biomedical Engineering

Background:

• Trans-spinal direct current stimulation (tsDCS) is an electro-modulatory technique explored for spinal cord injury rehabilitation.
• Previous research indicates lumbar tsDCS can yield significant modulatory effects on spinal networks.
• Understanding application-specific factors is crucial for advancing tsDCS in clinical settings.

Purpose of the Study:

• To investigate the influence of distinct electrode configurations in lumbar tsDCS on spinal excitability.
• To assess the impact of different polarities and electrode placements on neuromodulation.
• To explore potential correlations between BDNF genotype and tsDCS response.

Main Methods:

• Ten healthy subjects received tsDCS (2.5 mA, 15 min) with three electrode configurations: LSC-S, ED-Anodal, and ED-Cathodal, alongside a sham condition.
• Soleus H-reflex amplitude was measured pre-stimulation, during, and post-intervention.
• Subjects' BDNF genotypes were assessed to explore genetic influences on stimulation outcomes.

Main Results:

• The ED-Cathodal configuration significantly reduced H-reflex amplitude 30 minutes post-tsDCS compared to baseline.
• No significant post-intervention effects were observed with LSC-S or ED-Anodal configurations.
• BDNF genotype did not correlate with observed post-intervention effects on H-reflex amplitude.

Conclusions:

• Lumbar tsDCS, specifically the ED-Cathodal configuration, can induce spinal reflex depression, suggesting a potential mechanism for neuromodulation.
• The findings highlight the critical role of electrode configuration in tsDCS efficacy.
• Further research is needed to elucidate methodological and subject-specific factors influencing tsDCS outcomes for clinical application.