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What does the ratio of injected current to electrode area tell us about current density in the brain during tDCS?

2009-06Journal article Open access
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dc.contributor.authorMiranda, Pedro Cavaleiro
dc.contributor.authorFaria, Paula
dc.contributor.authorHallett, Mark
dc.contributor.authorPascoal-Faria, Paula
dc.date.accessioned2025-04-23T16:49:23Z
dc.date.available2025-04-23T16:49:23Z
dc.date.issued2009-06
dc.description.abstractObjective: To examine the relationship between the ratio of injected current to electrode area (I/A) and the current density at a fixed target point in the brain under the electrode during transcranial direct current stimulation (tDCS). Methods: Numerical methods were used to calculate the current density distribution in a standard spherical head model as well as in a homogeneous cylindrical conductor. Results: The calculations using the cylindrical model showed that, for the same I/A ratio, the current density at a fixed depth under the electrode was lower for the smaller of the two electrodes. Using the spherical model, the current density at a fixed target point in the brain under the electrode was found to be a non-linear function of the I/A ratio. For smaller electrodes, more current than predicted by the I/A ratio was required to achieve a predetermined current density in the brain. Conclusions: A non-linear relationship exists between the injected current, the electrode area and the current density at a fixed target point in the brain, which can be described in terms of a montage-specific I-A curve. Significance: I-A curves calculated using realistic head models or obtained experimentally should be used when adjusting the current for different electrode sizes or when comparing the effect of different current-electrode area combinations.eng
dc.description.sponsorshipThis work was supported in part by the NIH Intramural Pro gram, USA and by the Foundation for Science and Technology (FCT), Portugal. Paula Faria gratefully acknowledges the support of FCT under Grant SFRH/BD/29020/2006.
dc.identifier.citationPedro Cavaleiro Miranda, Paula Faria, Mark Hallett, What does the ratio of injected current to electrode area tell us about current density in the brain during tDCS?, Clinical Neurophysiology, Volume 120, Issue 6, 2009, Pages 1183-1187, ISSN 1388-2457, https://doi.org/10.1016/j.clinph.2009.03.023.
dc.identifier.doi10.1016/j.clinph.2009.03.023
dc.identifier.eissn1872-8952
dc.identifier.issn1388-2457
dc.identifier.urihttp://hdl.handle.net/10400.8/12834
dc.language.isoeng
dc.peerreviewedyes
dc.publisherElsevier
dc.relationSFRH/BD/29020/2006
dc.relation.hasversionhttps://www.sciencedirect.com/science/article/pii/S1388245709003046?via%3Dihub
dc.relation.ispartofClinical Neurophysiology
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/
dc.subjectStimulation
dc.subjectElectric
dc.subjectCurrent density
dc.subjectDirect current
dc.subjectPolarization
dc.subjectTranscranial
dc.subjecttDCS
dc.titleWhat does the ratio of injected current to electrode area tell us about current density in the brain during tDCS?eng
dc.typejournal article
dspace.entity.typePublication
oaire.citation.endPage1187
oaire.citation.issue6
oaire.citation.startPage1183
oaire.citation.titleClinical Neurophysiology
oaire.citation.volume120
oaire.versionhttp://purl.org/coar/version/c_970fb48d4fbd8a85
person.familyNamePascoal-Faria
person.givenNamePaula
person.identifier.ciencia-idE01D-874A-4145
person.identifier.orcid0000-0003-1474-9496
relation.isAuthorOfPublicationebb27133-d9ce-4f58-a4ca-f75a786bbc2e
relation.isAuthorOfPublication.latestForDiscoveryebb27133-d9ce-4f58-a4ca-f75a786bbc2e

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Objective: To examine the relationship between the ratio of injected current to electrode area (I/A) and the current density at a fixed target point in the brain under the electrode during transcranial direct current stimulation (tDCS). Methods: Numerical methods were used to calculate the current density distribution in a standard spherical head model as well as in a homogeneous cylindrical conductor. Results: The calculations using the cylindrical model showed that, for the same I/A ratio, the current density at a fixed depth under the electrode was lower for the smaller of the two electrodes. Using the spherical model, the current density at a fixed target point in the brain under the electrode was found to be a non-linear function of the I/A ratio. For smaller electrodes, more current than predicted by the I/A ratio was required to achieve a predetermined current density in the brain. Conclusions: A non-linear relationship exists between the injected current, the electrode area and the current density at a fixed target point in the brain, which can be described in terms of a montage-specific I-A curve. Significance: I-A curves calculated using realistic head models or obtained experimentally should be used when adjusting the current for different electrode sizes or when comparing the effect of different current-electrode area combinations.
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