TAP

TAP optimizes transcranial magnetic stimulation (TMS) coil placement and stimulation intensity using individualized MRI/fMRI-derived head models and electric field (E-field) simulations to maximize the E-field within a specified brain region of interest (ROI).

Key Features:

• Individualized Optimization: Uses MRI/fMRI-derived data and individualized head models, accounting for hair thickness and practical coil-positioning constraints to maximize the E-field at the target ROI.
• Integration with SimNIBS 3.2: Implements coil-placement optimization and E-field simulation using SimNIBS 3.2.
• Custom MATLAB Implementation: Implemented as custom MATLAB code for the optimization and data-processing steps.
• E-field Computation and Intensity Setting: Computes the E-field at the target site and facilitates selection of TMS device intensity settings to achieve desired E-field strengths.
• Neuronavigation Support: Prepares optimized coil placement data for use in neuronavigation systems and enables comparison of recorded coil placements to optimized positions.
• Accuracy Evaluation: Processes neuronavigation recordings post-experiment to quantify deviations in coil location and orientation; in a reported study across three repetitive TMS sessions in five subjects, deviations reached up to 2 mm in location and 2° in orientation, corresponding to an approximate 8% median decrease in target E-field magnitude.

Scientific Applications:

• Navigated TMS planning: Planning of coil placement and stimulation intensity for navigated TMS using MRI/fMRI-guided ROIs and E-field metrics.
• TMS intervention evaluation: Quantitative assessment of coil placement accuracy and delivered E-field using neuronavigation recordings.
• fMRI-guided neuromodulation research: Integration with fMRI-derived targets to improve reproducibility and targeting precision in neuroimaging and neuromodulation studies.

Methodology:

Custom MATLAB code uses MRI/fMRI-derived individualized head models, accounts for hair thickness and coil-positioning constraints, performs E-field simulation and optimization via SimNIBS 3.2, computes target E-fields to set device intensity, prepares data for neuronavigation, and post-processes neuronavigation recordings to assess location and orientation deviations.