Transcranial Pulsed Current Stimulation (tPCS)

In neurological disorders, changes in neuronal activities affect the brain – the critical control center of the human body – and can result in undesirable symptoms such as motor dysfunctions, irregular muscle tone, abnormal facial expression, cognitive and mental deficits, endocrine disorders, sleep disorders and digestive problems etc. Transcranial pulsed current stimulation (“tPCS”) is a type of non-invasive brain stimulation that delivers a low intensity, pulsed current to the cortex via surface electrodes attached to the scalp [1] to modulate the excitability [2]. tPCS is safe, well tolerated and has minimal side effects. The low intensity current delivered by tPCS is between 0.1mA to 2mA, about 800 times weaker than conventional Electroconvulsive therapy used in treating neuropsychiatry diseases.

The working mechanism of tPCS

The working mechanism of tPCS has been suggested to involve the induction of static and dynamic current components to modulate transmembrane neuronal potentials [2,3] which can influence the “Excitability/Inhibitory balance” of brain areas and regulate homeostasis in complex internal systems [4]. Research has shown that tPCS can influence functional connectivity of brain circuits [5] and interhemispheric coherence [6] between the brain hemispheres by entraining or desynchronizing endogenous oscillatory activity via rhythmic and stochastic resonance mechanism[7,8,9], leading to better performance of specific brain functions. For example, in upper motoneuron disorders, tPCS has been observed to increase corticospinal excitability [1,3] and may offer a possible mechanism to strengthen residual neural networks in the preserved brain regions that have taken over functions of the injured areas. Additionally, tPCS effects has also been reported in subcortical brain structures [10] such as the brain stem, the thalamus and the hypothalamus via modulation of cortical-subcortical pathways eg. cortico-thalamo-cerebellum loop and may therefore significantly impact the neurophysiology of diseases where the affected brain region is not near the cortical surface. Transcranial electrical stimulation is generally safe to be used in adult population under appropriate dosage [11] and even for pediatric population [12].

References:

[1] Jaberzadeh, S., Bastani, A., and Zoghi, M. (2014). Anodal transcranial pulsed current stimulation: a novel technique to enhance corticospinal excitability. Clin. Neurophysiol. 125, 344–351. doi: 10.1016/j.clinph.2013.08.025

[2] Nitsche, M.A.; Paulus,W. Excitability changes induced in the human motor cortex by weak transcranial direct current stimulation. J. Physiol. 2000, 527, 633–639.

[3] Jaberzadeh, S., Bastani, A., Zoghi, M., Morgan, P., and Fitzgerald, P. B. (2015). Anodal transcranial pulsed current stimulation: the effects of pulse duration on corticospinal excitability. Plos One 10: e131779. doi: 10.1371/journal.pone.0131779

[4] Deco, G., Ponce-Alvarez, A., Hagmann, P., Romani, G. L., Mantini, D., & Corbetta, M. (2014). How local excitation-inhibition ratio impacts the whole brain dynamics. The Journal of neuroscience : the official journal of the Society for Neuroscience, 34(23), 7886–7898.

[5] Sours, C., Alon, G., Roys, S., & Gullapalli, R. P. (2014). Modulation of resting state functional connectivity of the motor network by transcranial pulsed current stimulation. Brain connectivity, 4(3), 157–165.

[6] Morales-Quezada, L., Saavedra, L. C., Rozisky, J., Hadlington, L., and Fregni, F. (2014). Intensity-dependent effects of transcranial pulsed current stimulation on interhemispheric connectivity: a high-resolution qEEG, sham-controlled study. Neuroreport 25, 1054–1058. doi: 10.1097/WNR.0000000000000228

[7] Dissanayaka, T., Zoghi, M., Hill, A. T., Farrell, M., Egan, G., & Jaberzadeh, S. (2020). The Effect of Transcranial Pulsed Current Stimulation at 4 and 75 Hz on Electroencephalography Theta and High Gamma Band Power: A Pilot Study. Brain connectivity, 10(9),520–531.

[8] Schütt M, Claussen JC. Desynchronizing effect of high-frequency stimulation in a generic cortical network model. Cogn Neurodyn. 2012;6(4):343-351. doi:10.1007/s11571-012-9199-8

[9] Vasquez, A. C., Thibaut, A., Morales-Quezada, L., Leite, J., and Fregni, F. (2017). Patterns of brain oscillations across different electrode montages in transcranial pulsed current stimulation. Neuroreport 28, 421–425. doi: 10.1097/WNR.0000000000000772

[10] Datta A, Dmochowski JP, Guleyupoglu B, Bikson M, Fregni F. Cranial electrotherapy stimulation and transcranial pulsed current stimulation: a computer based high-resolution modeling study. Neuroimage. 2013 Jan 15 ;65:280-7. doi: 10.1016/j.neuroimage.2012.09.062. Epub 2012 Oct 5. PMID: 23041337.

[11] Antal A, Alekseichuk I, Bikson M, Brockmöller J, Brunoni AR, Chen R, Cohen LG, Dowthwaite G, Ellrich J, Flöel A, Fregni F, George MS, Hamilton R, Haueisen J, Herrmann CS, Hummel FC, Lefaucheur JP, Liebetanz D, Loo CK, McCaig CD, Miniussi C, Miranda PC, Moliadze V, Nitsche MA, Nowak R, Padberg F, Pascual-Leone A, Poppendieck W, Priori A, Rossi S, Rossini PM, Rothwell J, Rueger MA, Ruffini G, Schellhorn K, Siebner HR, Ugawa Y, Wexler A, Ziemann U, Hallett M, Paulus W. Low intensity transcranial electric stimulation: Safety, ethical, legal regulatory and application guidelines. Clin Neurophysiol. 2017 Sep;128(9):1774-1809. doi: 10.1016/j.clinph.2017.06.001. Epub 2017 Jun 19. PMID: 28709880; PMCID: PMC5985830.

[12] Krishnan C, Santos L, Peterson MD, Ehinger M. Safety of noninvasive brain stimulation in children and adolescents. Brain Stimul. 2015 Jan-Feb;8(1):76-87. doi: 10.1016/j.brs.2014.10.012. Epub 2014 Oct 28. PMID: 25499471; PMCID: PMC4459719.

Transcranial Pulsed Current Stimulation (tPCS)