Evaluation of the electric field in the brain during transcranial direct current stimulation: A sensitivity analysis.

Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference · 2016 · Unclear · Insufficient evidence

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UnclearInsufficient evidencePaper 2890

Study snapshot

PublicationAnnual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference · 2016

Study typeengineering

Reported directionUnclear

Evidence ratingInsufficient

Abstract

The use of computational modeling studies accounts currently for the best approach to predict the electric field (E-field) distribution in transcranial direct current stimulation. As with any model, the values attributed to the physical properties, namely the electrical conductivity of the tissues, affect the predicted E-field distribution. A wide range of values for the conductivity of most tissues is reported in the literature. In this work, we used the finite element method to compute the E-field induced in a realistic human head model for two electrode montages targeting the left dorso-lateral prefrontal cortex (DLPFC). A systematic analysis of the effect of different isotropic conductivity profiles on the E-field distribution was performed for the standard bipolar 7×5 cm2 electrodes configuration and also for an optimized multielectrode montage. Average values of the E-field's magnitude, normal and tangential components were calculated in the target region in the left DLPFC. Results show that the field decreases with increasing scalp, cerebrospinal fluid (CSF) and grey matter (GM) conductivities, while the opposite is observed for the skull and white matter conductivities. The tissues whose conductivity most affects the E-field in the cortex are the scalp and the CSF, followed by the GM and the skull. Uncertainties in the conductivity of individual tissues may affect electric field values by up to about 80%.

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AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typeengineering

Effect directionunclear

PopulationNot supplied

Sample sizeNot supplied

ExposureNot supplied

Evidence strengthInsufficientConfidence: 78% · Peer reviewed: yes

Main findings

Finite element modeling in a realistic human head model (two electrode montages targeting left DLPFC) found that predicted cortical E-field decreases with increasing scalp, CSF, and grey matter conductivities, while it increases with higher skull and white matter conductivities. The scalp and CSF conductivities had the largest influence on cortical E-field, and uncertainty in individual tissue conductivity could change E-field values by up to ~80%.

Outcomes measured

Modeled electric field (E-field) distribution in the brain/cortex during tDCS
Sensitivity of E-field magnitude and normal/tangential components in left DLPFC to tissue conductivity assumptions

Limitations

Computational modeling study; results depend on model assumptions and input tissue conductivity values
Only isotropic conductivity profiles were analyzed
Findings are about predicted E-field sensitivity, not direct health or clinical outcomes

View raw extracted JSON

{
  "study_type": "engineering",
  "exposure": {
    "band": null,
    "source": "transcranial direct current stimulation (tDCS)",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": null,
  "sample_size": null,
  "outcomes": [
    "Modeled electric field (E-field) distribution in the brain/cortex during tDCS",
    "Sensitivity of E-field magnitude and normal/tangential components in left DLPFC to tissue conductivity assumptions"
  ],
  "main_findings": "Finite element modeling in a realistic human head model (two electrode montages targeting left DLPFC) found that predicted cortical E-field decreases with increasing scalp, CSF, and grey matter conductivities, while it increases with higher skull and white matter conductivities. The scalp and CSF conductivities had the largest influence on cortical E-field, and uncertainty in individual tissue conductivity could change E-field values by up to ~80%.",
  "effect_direction": "unclear",
  "limitations": [
    "Computational modeling study; results depend on model assumptions and input tissue conductivity values",
    "Only isotropic conductivity profiles were analyzed",
    "Findings are about predicted E-field sensitivity, not direct health or clinical outcomes"
  ],
  "evidence_strength": "insufficient",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "tDCS",
    "transcranial direct current stimulation",
    "finite element method",
    "electric field",
    "head model",
    "tissue conductivity",
    "sensitivity analysis",
    "DLPFC",
    "electrode montage",
    "multielectrode montage"
  ],
  "suggested_hubs": [
    {
      "slug": "other",
      "weight": 0.3,
      "reason": "Engineering/computational modeling of electric fields during tDCS; not a typical environmental EMF exposure category."
    }
  ]
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1109/embc.2016.7591062
PubMed: 28268672

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