Transcranial Direct Current Stimulation (tDCS)

Overview

Transcranial direct current stimulation (tDCS) represents a neuromodulation technique that delivers a weak direct electrical current to the brain, and can be used to treat brain injuries, strokes, and other neural conditions. TDCS can be optimized and individualized through anatomic and patient-specific computational models that can simulate electric field distribution and current flow. Simpleware was used to develop Finite Element models of the human head, which have been used to create patient-specific therapy protocols for tDCS. These models have been used to optimize and individualize treatment of neurological conditions, enabling a better understanding of how tDCS can be safely applied.

Characteristics:

  • 3D FE models from MRI
  • Processing of segmented image data
  • Integration of CAD models with image data
  • Generation of an analysis ready volume mesh
  • Simulation of tDCS in COMSOL Multiphysics®

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Thanks to

Department of Biomedical Engineering, The City College of New York, CUNY and Soterix Medical, Inc
Marom Bikson • Abhishek Datta • Felipe Fregni • Jacek Dmochowski • Ole Seibt

Image Processing

MRI data scans of a healthy human head were obtained using a 3-T scanner. Researchers used in-house segmentation algorithms to define masks for skin, fat, skull, cerebral spinal fluid, gray and white matter. Image data was imported into ScanIP to enhance segmentation and demarcate tissue compartment boundaries. The Simpleware +CAD Module was also used to integrate electrodes, anodes, cathodes and sponge models into segmented image data.

Mesh Generation

The Simpleware +FE Module was used to convert segmented image data into a 3D volume mesh consisting of seven segmented tissue masks and an imported electrode montage. An adaptive +FE Free mesh algorithm was employed to reduce mesh elements without compromising computational accuracy. The exported mesh was high quality enough to remove the need for further smoothing prior to export.

Simulation

The head model was imported into COMSOL Multiphysics®, where electrostatic volume conductor physics were applied. Exterior boundaries and interior boundaries were defined, and anode placement was defined to take into account current flow. Material properties were also assigned to help simulate current distribution. The head model has subsequently been used as the basis for pre-treatment analysis of tDCS, enabling better patient protocols to be developed for areas such as skull defect and stroke treatment.