Abstract

Transcranial direct current stimulation (tDCS) of the human motor cortex induces changes in excitability within cortical and spinal circuits that occur during and after the stimulation. Recently, transcutaneous spinal direct current stimulation (tsDCS) has been shown to modulate spinal conduction properties, as assessed by somatosensory-evoked potentials, and transynaptic properties of the spinal neurons, as tested by postactivation depression of the H reflex or by the RIII nociceptive component of the flexion reflex in the lower limb. To further explore tsDCS-induced plastic changes in spinal excitability, we examined, in a double-blind crossover randomized study, the stimulus-response curves of the soleus H reflex before, during, at current offset and 15 min after anodal, cathodal, and sham tsDCS delivered at the Th11 level (2.5 mA, 15 min, 0.071 mA/cm(2), 0.064 C/cm(2)) in 17 healthy subjects. Anodal tsDCS induced a progressive leftward shift of the recruitment curve of the soleus H reflex during the stimulation; the effects persisted for at least 15 min after current offset. In contrast, both cathodal and sham tsDCS had no significant effects. This exploratory study provides further evidence for the use of tsDCS as an expedient, noninvasive tool to induce long-lasting plastic changes in spinal circuitry. Increased spinal excitability after anodal tsDCS may have potential for spinal neuromodulation in patients with central nervous system lesions.

Links

Publisher Full Text

Authors

Lamy JC, Ho C, Badel A, Arrigo RT, Boakye M

Institution

Stanford Neural Plasticity Laboratory, Palo Alto Veterans Health Care System and Department of Neurosurgery, Stanford University School of Medicine, Stanford, California, USA. jeancharles.lamy@gmail.com

Source

Journal of neurophysiology 108:3 2012 Aug 1 pg 906-14

MeSH

Adult
Evoked Potentials, Motor
Evoked Potentials, Somatosensory
Female
H-Reflex
Humans
Male
Muscle, Skeletal
Recruitment, Neurophysiological
Transcutaneous Electric Nerve Stimulation
Young Adult

Pub Type(s)

Journal Article
Randomized Controlled Trial
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

22623482