The importance of accurately representing electrode position in transcranial direct current stimulation computational models

Indahlastari, Aprinda; Dunn, Ayden L.; Pedersen, Samantha; Kraft, Jessica N.; Someya, Shizu; Albizu, Alejandro; Woods, Adam J.

doi:10.1016/j.brs.2023.05.010

Cited by 4 publications

(11 citation statements)

References 10 publications

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“…Our data confirmed substantial deviations from intended montages under routine, yet highly standardized experimental conditions. Deviations were more pronounced for IFG montages (>1 cm in ventral/posterior directions), thereby exceeding recommendations for negligible placement errors for conventional montages (Indahlastari et al, 2023). Notably, the margin for errors is likely smaller for focal set-ups due to their higher regional precision.…”

Section: Discussionmentioning

confidence: 84%

“…Deviations of electrodes from intended positions may be a central factor underlying variability of tDCS effects in experimental and computational studies (Indahlastari et al, 2023; Woods et al, 2015). Our data confirmed substantial deviations from intended montages under routine, yet highly standardized experimental conditions.…”

Section: Discussionmentioning

confidence: 99%

“…We cannot quantify how representative the degree of positioning errors in our study are. Indeed, such errors have largely been neglected in experimental and computational tDCS studies and positioning accuracy has rarely been investigated (Antonenko et al, 2019b; Indahlastari et al, 2023; Seibt et al, 2015). Similar to our own study, the majority of previous tDCS studies employed 10-20 EEG scalp coordinates for targeting (Thair et al, 2017), an approach with limited anatomical precision (De Witte et al, 2018).…”

Section: Limitationsmentioning

confidence: 99%

“…For example, a recent computational modeling study (Woods et al, 2015) demonstrated that 5% drift of large conventional rubber electrodes from their initial positions, equaling 1-1.5 cm on an average head, significantly altered the distribution of the electric field. Comparison of current flow simulations for “actual” electrode positions (derived from magnetic resonance imaging, MRI) with “virtual” electrodes representing “planned” montages, revealed less pronounced current flow in the latter (Indahlastari et al, 2023). Therefore, it was suggested that computational models of tDCS-induced current flow could be improved by accurately representing actual electrode positions (Opitz et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

“…However, the vast majority of previous tDCS studies did not administer the stimulation during fMRI (Ekhtiari et al, 2022; Ghobadi-Azbari et al, 2021) and the location of electrodes relative to intended target brain regions remained unknown. With few exceptions (Antonenko et al, 2019b; Indahlastari et al, 2023; Woods et al, 2015), actual electrode positions have also not been considered in computational studies (Hunold et al, 2023). Therefore, electrode positioning errors may explain some of the mixed results in experimental tDCS studies and computational studies investigating associations between current dose and behavioral, neurophysiological and neurochemical outcomes (Hunold et al, 2023).…”

Section: Introductionmentioning

confidence: 99%

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Electrode positioning errors reduce current dose for focal tDCS set-ups: Evidence from individualized electric field mapping

Niemann,

Riemann,

Hubert

et al. 2024

Preprint

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ObjectiveElectrode positioning errors contribute to variability of transcranial direct current stimulation (tDCS) effects. We investigated the impact of electrode positioning errors on current flow for tDCS set-ups with different focality.MethodsDeviations from planned electrode positions were determined using data acquired in an experimental study (N=240 datasets) that administered conventional and focal tDCS during magnetic resonance imaging (MRI). Comparison of individualized electric field modeling for planned and empirically derived “actual” electrode positions was conducted to quantify the impact of positioning errors on the electric field dose in target regions for tDCS.ResultsPlanned electrode positions resulted in higher current dose in the target regions for focal compared to conventional montages (7-12%). Deviations from planned positions significantly reduced current flow in the target regions, selectively for focal set-ups (26-30%). Dose reductions were significantly larger for focal compared to conventional set-ups (29-43%).ConclusionsPrecise positioning is crucial when using focal tDCS set-ups to avoid significant reductions of current dose in the intended target regions.SignificanceOur results highlight the urgent need to routinely implement methods for improving electrode positioning, minimization of electrode drift, verification of electrode positions before and/or after tDCS and also to consider positioning errors when investigating dose-response relationships, especially for focal set-ups.

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Section: Discussionmentioning

confidence: 84%

Section: Discussionmentioning

confidence: 99%

Section: Limitationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electrode positioning errors reduce current dose for focal tDCS set-ups: Evidence from individualized electric field mapping

Niemann,

Riemann,

Hubert

et al. 2024

Preprint

View full text Add to dashboard Cite

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Electrode positioning errors reduce current dose for focal tDCS set-ups: Evidence from individualized electric field mapping

Niemann,

Riemann,

Hubert

et al. 2024

Clinical Neurophysiology

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Impact of electrode selection on modeling tDCS in the aging brain

Indahlastari,

Dunn,

Pedersen

et al. 2023

Front. Hum. Neurosci.

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BackgroundPerson-specific computational models can estimate transcranial direct current stimulation (tDCS) current dose delivered to the brain and predict treatment response. Artificially created electrode models derived from virtual 10–20 EEG measurements are typically included in these models as current injection and removal sites. The present study directly compares current flow models generated via artificially placed electrodes (“artificial” electrode models) against those generated using real electrodes acquired from structural MRI scans (“real” electrode models) of older adults.MethodsA total of 16 individualized head models were derived from cognitively healthy older adults (mean age = 71.8 years) who participated in an in-scanner tDCS study with an F3-F4 montage. Visible tDCS electrodes captured within the MRI scans were segmented to create the “real” electrode model. In contrast, the “artificial” electrodes were generated in ROAST. Percentage differences in current density were computed in selected regions of interest (ROIs) as examples of stimulation targets within an F3-F4 montage.Main resultsWe found significant inverse correlations (p < 0.001) between median current density values and brain atrophy in both electrode pipelines with slightly larger correlations found in the artificial pipeline. The percent difference (PD) of the electrode distances between the two models predicted the median current density values computed in the ROIs, gray, and white matter, with significant correlation between electrode distance PDs and current density. The correlation between PD of the contact areas and the computed median current densities in the brain was found to be non-significant.ConclusionsThis study demonstrates potential discrepancies in generated current density models using real versus artificial electrode placement when applying tDCS to an older adult cohort. Our findings strongly suggest that future tDCS clinical work should consider closely monitoring and rigorously documenting electrode location during stimulation to model tDCS montages as closely as possible to actual placement. Detailed physical electrode location data may provide more precise information and thus produce more robust tDCS modeling results.

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The importance of accurately representing electrode position in transcranial direct current stimulation computational models

Cited by 4 publications

References 10 publications

Electrode positioning errors reduce current dose for focal tDCS set-ups: Evidence from individualized electric field mapping

Electrode positioning errors reduce current dose for focal tDCS set-ups: Evidence from individualized electric field mapping

Electrode positioning errors reduce current dose for focal tDCS set-ups: Evidence from individualized electric field mapping

Impact of electrode selection on modeling tDCS in the aging brain

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