DaSilva AF received funding support from CTSA high-tech funding grant, University of Michigan to complete this review. Volz MS is funded by a grant scholarship from Stiftung Charit&eacute;.

<ol>
	<li>Fregni, F., Pascual-Leone, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Technology+insight:+noninvasive+brain+stimulation+in+neurology-perspectives+on+the+therapeutic+potential+of+rTMS+and+tDCS.">Technology insight: noninvasive brain stimulation in neurology-perspectives on the therapeutic potential of rTMS and tDCS.</a> Nat Clin Pract Neurol. 3 (7), 383-383 (2007).</li><li>Wagner, T., Valero-Cabre, A., Pascual-Leone, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Noninvasive+human+brain+stimulation.">Noninvasive human brain stimulation.</a> Annu Rev Biomed Eng. 9, 527-527 (2007).</li><li>Fregni, F., Freedman, S., Pascual-Leone, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+advances+in+the+treatment+of+chronic+pain+with+non-invasive+brain+stimulation+techniques.">Recent advances in the treatment of chronic pain with non-invasive brain stimulation techniques.</a> Lancet Neurol. 6 (2), 188-188 (2007).</li><li>Lefaucheur, J. P., Antal, A., Ahdab, R., Ciampi de Andra, D., Fregni, F., Khedr, E. M., Nitsche, M., Paulus, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+use+of+repetitive+transcranial+magnetic+stimulation+(rTMS)+and+transcranial+direct+current+stimulation+(tDCS)+to+relieve+pain.">The use of repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) to relieve pain.</a> Brain Stimul. 1 (4), 337-337 (2008).</li><li>Antal, A., Paulus, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcranial+magnetic+and+direct+current+stimulation+in+the+therapy+of+pain.">Transcranial magnetic and direct current stimulation in the therapy of pain.</a> Schmerz Apr. 24 (2), 161-161 (2010).</li><li>Nitsche, M. A., Paulus, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Excitability+changes+induced+in+the+human+motor+cortex+by+weak+transcranial+direct+current+stimulation.">Excitability changes induced in the human motor cortex by weak transcranial direct current stimulation.</a> J Physiol. 527 (Pt 3), 633-633 (2000).</li><li>Nitsche, M. A., Cohen, L. G., Wassermann, E. M., Priori, A., Lang, N., Antal, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcranial+direct+current+stimulation:+state+of+the+art.">Transcranial direct current stimulation: state of the art.</a> Brain Stimul. 11, 642-642 (2008).</li><li>Merrill, D. R., Bikson, M., Jefferys, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrical+stimulation+of+excitable+tissue:+design+of+efficacious+and+safe+protocols.">Electrical stimulation of excitable tissue: design of efficacious and safe protocols.</a> J Neurosci Methods. 141 (2), 171-171 (2005).</li><li>Boggio, P. S., Khoury, L. P., Martins, D. C., Martins, O. E., de Macedo, E. C., Fregni, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Temporal+cortex+direct+current+stimulation+enhances+performance+on+a+visual+recognition+memory+task+in+Alzheimer+disease.">Temporal cortex direct current stimulation enhances performance on a visual recognition memory task in Alzheimer disease.</a> J Neurol Neurosurg Psychiatry. 80 (4), 444-444 (2009).</li><li>Fregni, F., Boggio, P. S., Nitsche, M., Bermpohl, F., Antal, A., Feredoes, E., Marcolin, M. A., Rigonatti, S. P., Silva, M. T., Paulus, W., Pascual-Leone, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anodal+transcranial+direct+current+stimulation+of+prefrontal+cortex+enhances+working+memory.">Anodal transcranial direct current stimulation of prefrontal cortex enhances working memory.</a> Exp Brain Res. 166 (1), 23-23 (2005).</li><li>Dundas, J. E., Thickbroom, G. W., Mastaglia, F. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Perception+of+comfort+during+transcranial+DC+stimulation:+effect+of+NaCl+solution+concentration+applied+to+sponge+electrodes.">Perception of comfort during transcranial DC stimulation: effect of NaCl solution concentration applied to sponge electrodes.</a> Clin Neurophysiol. 118 (5), 1166-1166 (2007).</li><li>Minhas, P., Datta, A., Bikson, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cutaneous+perception+during+tDCS:+Role+of+electrode+shape+and+sponge+salinity.">Cutaneous perception during tDCS: Role of electrode shape and sponge salinity.</a> Clin Neurophysiol. 11, (2010).</li><li>Antal, A., Terney, D., Poreisz, C., Paulus, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Towards+unravelling+task-related+modulations+of+neuroplastic+changes+induced+in+the+human+motor+cortex.">Towards unravelling task-related modulations of neuroplastic changes induced in the human motor cortex.</a> Eur J Neurosci. 26 (9), 2687-2687 (2007).</li><li>Datta, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gyri-precise+head+model+of+transcranial+direct+current+stimulation:+improved+spatial+focality+using+a+ring+electrode+versus+conventional+rectangular+pad.">Gyri-precise head model of transcranial direct current stimulation: improved spatial focality using a ring electrode versus conventional rectangular pad.</a> Brain Stimul. 2 (4), 201-201 (2009).</li><li>Minhas, P., Bansal, V., Patel, J., Ho, J. S., Diaz, J., Datta, A., Bikson, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrodes+for+high-definition+transcutaneous+DC+stimulation+for+applications+in+drug+delivery+and+electrotherapy,+including+tDCS.">Electrodes for high-definition transcutaneous DC stimulation for applications in drug delivery and electrotherapy, including tDCS.</a> J Neurosci Methods. 190 (2), (2010).</li><li>Brunoni, A. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Systematic+Review+on+Reporting+and+Assessment+of+Adverse+Effects+associated+with+Transcranial+Direct+Current+Stimulation.">A Systematic Review on Reporting and Assessment of Adverse Effects associated with Transcranial Direct Current Stimulation.</a> Int J Neuropsychopharmacol. , (2011).</li><li>Wagner, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcranial+direct+current+stimulation:+a+computer-based+human+model+study.">Transcranial direct current stimulation: a computer-based human model study.</a> Neuroimage. 35 (3), 1113-1113 (2007).</li><li>Nitsche, M. A., Doemkes, S., Karaköse, T., Antal, A., Liebetanz, D., Lang, N., Tergau, F., Paulus, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shaping+the+effects+of+transcranial+direct+current+stimulation+of+the+human+motor+cortex.">Shaping the effects of transcranial direct current stimulation of the human motor cortex.</a> J Neurophysiol. 97 (4), 3109-3109 (2007).</li><li>Wagner, T., Fregni, F., Fecteau, S., Grodzinsky, A., Zahn, M., Pascual-Leone, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcranial+direct+current+stimulation:+a+computer-based+human+model+study.">Transcranial direct current stimulation: a computer-based human model study.</a> Neuroimage. 35 (3), 1113-1113 (2007).</li><li>Boggio, P. S., Rigonatti, S. P., Ribeiro, R. B., Myczkowski, M. L., Nitsche, M. A., Pascual-Leone, A., Fregni, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+randomized,+double-blind+clinical+trial+on+the+efficacy+of+cortical+direct+current+stimulation+for+the+treatment+of+major+depression.">A randomized, double-blind clinical trial on the efficacy of cortical direct current stimulation for the treatment of major depression.</a> Int J Neuropsychopharmacol. 11 (2), 249-249 (2008).</li><li>Williams, J. A., Pascual-Leone, A., Fregni, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interhemispheric+modulation+induced+by+cortical+stimulation+and+motor+training.">Interhemispheric modulation induced by cortical stimulation and motor training.</a> Phys Ther. 90 (3), 398-398 (2010).</li><li>Lang, N., Nitsche, M. A., Rothwel, J. C., Williams, J. A., Lemon, R. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+transcranial+direct+current+stimulation+over+the+human+motor+cortex+on+corticospinal+and+transcallosal+excitability.">Effects of transcranial direct current stimulation over the human motor cortex on corticospinal and transcallosal excitability.</a> Exp Brain Res. 156 (4), 439-439 (2004).</li><li>Bikson, M., Datta, A., Rahman, A., Scaturro, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrode+montages+for+tDCS+and+weak+transcranial+electrical+stimulation:+role+of+"return"+electrode's+position+and+size.">Electrode montages for tDCS and weak transcranial electrical stimulation: role of "return" electrode's position and size.</a> Clin Neurophysiol. 121 (12), (1976).</li><li>Bikson, M., Fregni, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcranial+direct+current+stimulation+in+patients+with+skull+defects+and+skull+plates:+high-resolution+computational+FEM+study+of+factors+altering+cortical+current+flow.">Transcranial direct current stimulation in patients with skull defects and skull plates: high-resolution computational FEM study of factors altering cortical current flow.</a> Neuroimage. 52 (4), 1268-1268 (2010).</li><li>Datta, A., Baker, J. M., Bikson, M., Fridriksson, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Individualized+model+predicts+brain+current+flow+during+transcranial+direct-current+stimulation+treatment+in+responsive+stroke+patient.">Individualized model predicts brain current flow during transcranial direct-current stimulation treatment in responsive stroke patient.</a> Brain Stimulation. , (2011).</li><li>Palm, U., Keeser, D., Schiller, C., Fintescu, Z., Nitsche, M., Reisinger, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Padberg+Skin+lesions+after+treatment+with+transcranial+direct+current+stimulation+(tDCS).">Padberg Skin lesions after treatment with transcranial direct current stimulation (tDCS).</a> Brain Stimul. 1 (4), 386-386 (2008).</li><li>Datta, A., Elwassif, M., Bikson, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bio-heat+transfer+model+of+transcranial+DC+stimulation:+comparison+of+conventional+pad+versus+ring+electrode.">Bio-heat transfer model of transcranial DC stimulation: comparison of conventional pad versus ring electrode.</a> Conf Proc IEEE Eng Med Biol Soc. , 670-670 (2009).</li><li>Miranda, P. C., Faria, P., Hallett, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=What+does+the+ratio+of+injected+current+to+electrode+area+tell+us+about+current+density+in+the+brain+during+tDCS?.">What does the ratio of injected current to electrode area tell us about current density in the brain during tDCS?.</a> Clin Neurophysiol. 120 (6), 1183-1183 (2009).</li><li>Gandiga, P. C., Hummel, F. C., Cohen, L. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcranial+DC+stimulation+(tDCS):+a+tool+for+double-blind+sham-controlled+clinical+studies+in+brain+stimulation.">Transcranial DC stimulation (tDCS): a tool for double-blind sham-controlled clinical studies in brain stimulation.</a> Clin Neurophysiol. 117 (4), 845-845 (2006).</li><li>Antal, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparatively+weak+after-effects+of+transcranial+alternating+current+stimulation+(tACS)+on+cortical+excitability+in+humans.">Comparatively weak after-effects of transcranial alternating current stimulation (tACS) on cortical excitability in humans.</a> Brain Stimul. 1 (2), 97-97 (2008).</li><li>Terney, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Increasing+human+brain+excitability+by+transcranial+high-frequency+random+noise+stimulation.">Increasing human brain excitability by transcranial high-frequency random noise stimulation.</a> J Neurosci Methods. 28 (52), 14147-14147 (2008).</li><li>Fregni, F., Boggio, P. S., Mansur, C. G., Wagner, T., Ferreira, M. J., Lima, M. C., Rigonatti, S. P., Marcolin, M. A., Freedman, S. D., Nitsche, M. A., Pascual-Leone, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcranial+direct+current+stimulation+of+the+unaffected+hemisphere+in+stroke+patients.">Transcranial direct current stimulation of the unaffected hemisphere in stroke patients.</a> Neuroreport. 16 (14), 1551-1551 (2005).</li><li>Antal, A., Terney, D., K hnl, S., Paulus, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anodal+transcranial+direct+current+stimulation+of+the+motor+cortex+ameliorates+chronic+pain+and+reduces+short+intracortical+inhibition.">Anodal transcranial direct current stimulation of the motor cortex ameliorates chronic pain and reduces short intracortical inhibition.</a> J Pain Symptom Manage. 39 (5), (2010).</li><li>Fregni, F., Gimenes, R., Valle, A. C., Ferreira, M. J., Rocha, R. R., Natalle, L., Bravo, R., Rigonatti, S. P., Freedman, S. D., Nitsche, M. A., Pascual-Leone, A., Boggio, P. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+randomized,+sham-controlled,+proof+of+principle+study+of+transcranial+direct+current+stimulation+for+the+treatment+of+pain+in+fibromyalgia.">A randomized, sham-controlled, proof of principle study of transcranial direct current stimulation for the treatment of pain in fibromyalgia.</a> Arthritis Rheum. 54 (12), (2006).</li><li>Boggio, P. S., Zaghi, S., Lopes, M., Fregni, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modulatory+effects+of+anodal+transcranial+direct+current+stimulation+on+perception+and+pain+thresholds+in+healthy+volunteers.">Modulatory effects of anodal transcranial direct current stimulation on perception and pain thresholds in healthy volunteers.</a> Eur J Neurol. 15 (10), 1124-1124 (2008).</li><li>Fregni, F., Liguori, P., Fecteau, S., Nitsche, M. A., Pascual-Leone, A., Boggio, P. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cortical+stimulation+of+the+prefrontal+cortex+with+transcranial+direct+current+stimulation+reduces+cue-provoked+smoking+craving:+a+randomized,+sham-controlled+study.">Cortical stimulation of the prefrontal cortex with transcranial direct current stimulation reduces cue-provoked smoking craving: a randomized, sham-controlled study.</a> J Clin Psychiatry. 69 (1), 32-32 (2006).</li></ol>

The City University of New York holds patents on brain stimulation, on which Marom Bikson is an inventor. Marom Bikson is a co-founder of Soterix Medical Inc.

Critical Steps:
Aspects to be checked prior to starting procedure:
<ul>
<li>First of all, patients should be screened for whether there are any contraindications for tDCS - these contraindications may be application specific. This includes questions such as presence of severe or frequent headache, chronic skin disorder, or adverse reactions to a previous tDCS treatment. If he or she has any metal in the head or had a serious brain injury, the anatomical changes may modify current flow23,24. History of seizure, pregnancy and history of a stroke are usually not strict contraindications - and indeed, might be inclusion criteria in some clinical trials.</li> 
<li>Check for any lesions on the scalp- additionally subjects should be specifically interviewed and inspected for the existence of skin diseases. If there are any lesions, tDCS procedure should be avoided or, if appropriate, ensured that stimulation will not be conducted directly over or across the lesion. Stimulation of a different site can be considered. It is reported that repeated daily tDCS causes clinically significant skin irritation under the electrodes in some patients7. There is evidence of tDCS induced lesions according to skin integrity. For instance, it has been shown extensive redness and brown crusty intracutaneous changes with irregular round shapes due to tDC stimulation at an intensity of 2 mA for a period of 2 weeks including five sessions each week25. If tDCS is strongly indicated or has to be conducted, it is possible to take into consideration to stimulate with a lower intensity such as 0.5- 1.0 mA, but it is not guaranteed that this will prevent skin irritations or lesions. Thus, the condition of the skin under the electrodes should be inspected before and after tDCS7.</li>
<li>Check connectors of cables for electrolysis. Use another pair if evident. It is recommended to check the cables after approximately two months of use.</li>
</ul>
During both- active or sham- tDCS always ask whether subject still feels comfortable and is able to continue procedure.
Possible modifications:
<ul>
<li>There are many varieties of electrode positioning7 (Table 2).</li>
<li>There are many varieties of electrode sizes26 (Figure 7). For a given applied current, electrode size influences the current density18 and influences the focality of brain modulation (Figure 8). Clinical studies have suggest the smaller the size of the electrode the larger the current density26, however modelling studies suggest that the relationship between electrode size and area of brain modulation may be more complex27. Furthermore, the effects of small electrodes can differ qualitatively due to differential shunting of current in the scalp, and greater edge effect relative to the overall electrode area7. There were drastically superior levels of shunting for small electrode sizes reported than for the larger electrode schemes19.</li> 
<li>High-Definition tDCS (HD-tDCS) is a technology that improves spatial focality but requires special hardware and procedural controls15.</li> 
<li>The electrode montage (electrode position and size) along with the applied current determine the generated electrical field strength in the brain which, in turn, determines the efficacy of tDCS. The use of just electrode current density, defined by the ratio between the current strength and the electrode size, has been proposed to normalize clinical outcomes &#x2013; but modelling studies suggest this may only apply over a limited range and that overall electrode montage design determines outcome. Generally, increasing current intensity (or current density) for any given montage result in stronger effects. It is important to note that the current density at the skin surface is much higher than that in the brain19 (Figure 9).</li>
<li>The position of the "return" ("reference") electrode may influence the overall current flow pattern through the brain, and thus even influence brain modulation under the active electrodes22. Thus the potion of both electrodes should be considered.</li>
<li>The duration of the stimulation depends on the aim of the experimental approach. An increase of duration of the stimulation is associated with the occurrence and a longer duration of after-effects3,4. However at least one study reported a reversal of effects directions when stimulation duration was increased, suggesting that more intensity does not necessarily translate into a more robust clinical outcome. Though tDCS within published parameters is considered safe and well tolerated, the potential for undesired side-effects increases with increasing intensity (time, duration, or repetition rate/number).</li>
<li>Orientation of the electric field: defined by the electrodes positions and polarity. Cathodal stimulation typically decreases cortical excitability, whereas anodal stimulation typically increases the cortical excitability2,3.</li> 
<li>Placebo: For sham-tDCS the same protocol above is used. However, the current will be applied for 30 seconds. This is one of the advantages of tDCS compared to other non-invasive brain stimulation methods. Since the arising sensations resulted from active-tDCS tend to occur only at early stages of application, this sham method makes it difficult for the patient to distinguish the placebo from active tDCS application. This initial and brief stimulation is a reliable method of placebo28.</li>
<li>Note that the technique can also be applied when using other transcranial electric therapies such as tACS29 or tRNS30.</li> 
</ul>
Rationale for using tDCS in chronic pain:
The fact that multiple therapeutic pharmacological modalities provide only modest relief for chronic pain patients raises the possibility that the cause for the persistence of this debilitating disorder may lie within plastic changes in pain related neural networks. Interestingly, modulation of cortical activity can be achieved non-invasively by tDCS, as described earlier, which has been reported to produce lasting therapeutic effects in chronic pain due to changes in cortical plasticity.
Clinical effect of tDCS in chronic pain:
It has been shown that tDCS applied to the motor cortex changes the local cortical excitability (Figure 6)6. More precisely, anodal stimulation results in an increase of neuronal excitability, whereas cathodal stimulation has opposite results6. Indeed, anodal tDCS application over M1 leads to a greater improvement in visual analogue scale (VAS) pain ratings than sham tDCS. This therapeutic effect on pain following M1 stimulation, although transient, was reproduced in several groups of patients with neuropathic pain syndromes like trigeminal neuralgia, poststroke pain syndrome31, back pain and fibromyalgia32. Interestingly, clinical trials in neuropathic pain, due to spinal cord injury, stimulation of the motor cortex by tDCS showed pain improvement and cumulative analgesic effect that lasted two weeks after the stimulation. There is also evidence of its analgesic effect in fibromyalgia patients33 that is still significant after three weeks of follow-up for anodal tDCS of the M1 compared with sham stimulation, and as well as stimulation of the DLPFC33. Although the effects of anodal tDCS over DLFPC for pain improvement have not been explored extensively, it was shown it can be used to modulate pain thresholds in healthy subjects34. Nevertheless, stimulation of this brain area is a reliable technique for enhancing working memory 10, increasing performance on memory tasks in Alzheimer disease9 and reducing cue-provoked smoking craving significantly35 for instance; therefore it is also conceivable that this might be a useful strategy to modulate affective-emotional cognitive networks associated with pain processing in patients with chronic pain.

electrode positioning and montage in transcranial direct current stimulation

Transcranial direct current stimulation (tDCS) is a technique that has been intensively investigated in the past decade as this method offers a non-invasive and safe alternative to change cortical excitability2. The effects of one session of tDCS can last for several minutes, and its effects depend on polarity of stimulation, such as that cathodal stimulation induces a decrease in cortical excitability, and anodal stimulation induces an increase in cortical excitability that may last beyond the duration of stimulation6. These effects have been explored in cognitive neuroscience and also clinically in a variety of neuropsychiatric disorders &#x2013; especially when applied over several consecutive sessions4. One area that has been attracting attention of neuroscientists and clinicians is the use of tDCS for modulation of pain-related neural networks3,5. Modulation of two main cortical areas in pain research has been explored: primary motor cortex and dorsolateral prefrontal cortex7. Due to the critical role of electrode montage, in this article, we show different alternatives for electrode placement for tDCS clinical trials on pain; discussing advantages and disadvantages of each method of stimulation.

Watch this Scientific Journal Video about Electrode Positioning and Montage in Transcranial Direct Current Stimulation at JoVE.com

Electrode Positioning and Montage in Transcranial Direct Current Stimulation

Transcranial direct current stimulation (tDCS) is an established technique to modulate cortical excitability1,2. It has been used as an investigative tool in neuroscience due to its effects on cortical plasticity, easy operation, and safe profile. One area that tDCS has been showing encouraging results is pain alleviation 3-5.

Transcranial direct current stimulation (tDCS) is a technique that has been intensively investigated in the past decade as this method offers a ...

electrode-positioning-montage-transcranial-direct-current

Research

JoVE Journal

Neuroscience

261.2K visualizações.  University of Michigan. Estimulação transcraniana por corrente (ETCC) é uma técnica estabelecida para modular a excitabilidade cortical 1,2. Ela tem sido usada como uma ferramenta de investigação em neurociência, devido aos seus efeitos sobre a plasticidade cortical, de fácil operação e perfil de segurança. Uma área que ETCC vem mostrando resultados animadores é alívio da dor 05/03.