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 30min after application of four experimental conditions: (1) a-tDCS, (2) a-tPCS with short inter-pulse interval (a-tPCSSIPI, 50ms), (3) a-tPCS with long inter-pulse interval (a-tPCSLIPI., 650ms) 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-tPCSSIPI (P<0.05) induced significant increases in CSE, lasted for at least 30min. Post-hoc tests indicated that this increase was larger in a-tPCSSIPI (P<0.05). There were no significant changes following application of a-tPCSLIPI and sham a-tPCS. All participants tolerated the applied currents in all experimental conditions very well. CONCLUSIONS Compared to a-tDCS, a-tPCSSIPI 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.

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