A 15-minute session of direct current stimulation does not produce lasting changes in axonal excitability - 13/06/19

Doi : 10.1016/j.neucli.2019.05.067

André Caetano ^a,^b, Mariana Pereira ^a, Mamede de Carvalho ^a,^c,^⁎
^a Institute of Physiology, Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
^b Department of Neurology, Hospital de Egas Moniz, Centro Hospitalar de Lisboa Ocidental, Lisbon, Portugal
^c Department of Neurosciences and Mental Health, Hospital de Santa Maria, Centro Hospitalar Universitario de Lisboa-Norte, Lisbon, Portugal

^⁎Corresponding author at: Institute of Physiology, Faculty of Medicine, University of Lisbon, avenue Professor Egas-Moniz, 1649-028 Lisboa, Portugal.Institute of Physiology, Faculty of Medicine, University of Lisbonavenue Professor Egas-MonizLisboa1649-028Portugal

En prensa. Pruebas corregidas por el autor. Disponible en línea desde el Thursday 13 June 2019
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Summary

Objective

To assess the applicability and lasting effects on axonal membrane excitability of transcutaneous peripheral nerve direct current stimulation (pDCS).

Methods

We included 15 healthy subjects. pDCS was performed with the active electrode placed over the left forearm and the reference electrode on the back of the hand. We used 5×5cm rubber electrodes and the current applied was 2.5mA during 15minutes. Three pDCS sessions were performed on the same day with a 20-minute interval between them: first a sham stimulation, followed by cathodal and anodal stimulations in random order. Motor nerve excitability measurements were performed immediately after each pDCS session using the TRONDNF nerve excitability protocol of the QTRAC program.

Results

The protocol was completed and well tolerated in all subjects. There were no consistent significant differences in excitability measurements between the three sessions.

Conclusions

No consistent long-lasting effects were noted on peripheral nerve excitability beyond the period of application of pDCS. We showed that a 15-minute session of DCS is not able to produce lasting changes in axonal excitability, supporting the hypothesis that the functional and clinical impact of DCS protocols applied to the central nervous system is related to long-term synaptic changes rather sustained local changes in axonal rest membrane potential.

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Keywords : Anodal/cathodal current, Direct current stimulation, Nerve excitability, Threshold tracking