Anodal transcranial pulsed current stimulation: A novel technique to enhance corticospinal excitability

Objective: We aimed to compare the effects of anodal-transcranial pulsed current stimulation (a-tPCS) with conventional anodal transcranial direct current stimulation (a-tDCS) on corticospinal excitability (CSE) in healthy individuals. Methods: CSE of the dominant primary motor cortex of the resting right extensor carpi radialis muscle was assessed before, immediately, 10, 20 and 30 min after application of four experimental conditions: (1) a-tDCS, (2) a-tPCS with short inter-pulse interval (a-tPCS(SIPI), 50 ms), (3) a-tPCS with long inter-pulse interval (a-tPCS(LIPI)., 650 ms) and (4) sham a-tPCS. The total charges were kept constant in all experimental conditions except sham condition. The outcome measure in this study was motor evoked potentials. Results: Only a-tDCS and a-tPCS(SIPI) (P < 0.05) induced significant increases in CSE, lasted for at least 30 min. Post-hoc tests indicated that this increase was larger in a-tPCS(SIPI) (P < 0.05). There were no significant changes following application of a-tPCS(LIPI) and sham a-tPCS. All participants tolerated the applied currents in all experimental conditions very well. Conclusions: Compared to a-tDCS, a-tPCS(SIPI) is a better technique for enhancement of CSE. There were no sham effects for application of a-tPCS. However, unlike a-tDCS which modifies neuronal excitability by tonic depolarization of the resting membrane potential, a-tPCS modifies neuronal excitability by a combination of tonic and phasic effects. Significance: a-tPCS could be considered as a promising neuromodulatory tool in basic neuroscience and as a therapeutic technique in neurorehabilitation. (C) 2013 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.