EEG Dipole Simulator & Anatomical Demo

A lightweight, interactive web-based tool designed to build an intuitive understanding of EEG forward modeling. This simulation visualizes how a neural source (modeled as a current dipole) generates electrical potentials across the scalp, bridging the gap between underlying brain activity and the waveforms seen on an EEG monitor.

It features a Zero-Dependency architecture, contained entirely within a single HTML file for easy sharing and offline use.

Run Demo at https://dbrang.github.io/EEG-Dipole-Demo/

🎯 Purpose

Understanding EEG requires grasping the "Inverse Problem" (guessing the source from the scalp) and the "Forward Problem" (calculating the scalp potential from a known source). This tool visualizes the Forward Problem in real-time, helping students and researchers understand:

• Dipole Orientation: The difference between Radial and Tangential sources.
• Volume Conduction: How the skull and scalp attenuate and smear electrical fields.
• Montage Geometry: The relationship between a coronal slice (T3-C3-Cz-C4-T4) and the full 10-20 scalp topomap.
• Reference Issues: How switching to an "Average Reference" changes the observed potentials.

✨ Key Features

• Dual-View Visualization:
  • Coronal View (Left): A cross-sectional anatomical view showing the brain, skull, and scalp layers. It highlights the "Coronal Chain" of electrodes (T3, C3, Cz, C4, T4).
  • Scalp Topomap (Right): A classic 2D heatmap (interpolation) of the voltage distribution across a standard 10-20 electrode montage.
• Interactive Physics:
  • Move the Source: Drag the dipole X/Y position to see how depth affects signal strength and spread.
  • Rotate Orientation: Adjust the dipole angle to simulate radial vs. tangential activity.
  • Adjust Strength: Change the dipole moment to see signal-to-noise impacts.
• Real-Time Rendering:
  • Instantaneous calculation of potential fields.
  • Dynamic plotting of electric field lines (streamlines).
• Customization:
  • Toggle Average Reference calculation.
  • Show/Hide electrode labels.
  • Auto-rotate animation mode.

🚀 Quick Start

There is no build process, no npm install, and no server required.

1. Download the eeg_dipole_demo_anatomical_v11.html file.
2. Open the file in any modern web browser (Chrome, Firefox, Safari, Edge).
3. Interact with the sliders on the right panel to simulate brain activity.

🛠️ Technical Details

• Stack: Vanilla JavaScript, HTML5 Canvas.
• Dependencies: None.
• Math:
  • The simulation approximates a multi-shell spherical head model.
  • Potentials are calculated using the inverse-square law modified for conductive layers (Brain $\to$ Skull $\to$ Scalp).
  • Topographic mapping utilizes Inverse Distance Weighting (IDW) for smooth heatmap interpolation between electrode sites.

🎮 Controls Guide

Control	Function
Source X / Y	Moves the dipole location within the coronal slice.
Orientation	Rotates the dipole (0° = Up/Radial, 90° = Right/Tangential).
Moment	Increases or decreases the simulated current strength.
Field Lines	Toggles the visualization of current flow lines in the coronal view.
Avg Ref	Re-calculates potentials by subtracting the mean of all electrodes (Common Average Reference).
Auto-Rotate	Automatically spins the dipole to demonstrate changing field polarities.

📄 License

Distributed under the MIT License. See LICENSE for more information.

---

Developed for educational purposes in Neuroscience and Signal Processing.