- Prolate1 -

3-d EEG Potential Field Interpolation on a Prolate Spheroid

Prolate1 is an ongoing experimental software application for Power Macintosh computers which can read and display time-varying EEG electric field potential on the surface of a prolate spheroid. A prolate spheroid of variable eccentricity is used to provide a more accurate model of the geometry of the human head than is possible with a simple sphere.

Time-series EEG data from multiple sensors located at arbitrary positions on a spheroid are read into the program and used to interpolate values of the field at other, arbitrary, lattice points contained on the spheroid. These interpolated values are then used to color surface patches of the spheroid, and to create a dynamic color animation of the field in 3-d as it changes over time.

The 3-d images produced by the Prolate1 program can be freely rotated and zoomed in real-time with the mouse or keyboard. Individual frames of an animation of the potential field can be generated and displayed in real-time from the time-series sensor data.

The image above shows the following aspects of the Prolate1 software, from left to right, top to bottom:

  1. A wireframe representation of the spheroid.
  2. The lattice points of the spheroid color-coded to show association with elements of the sensor triangulation.
  3. One frame of an animation of real EEG data.
  4. Another frame of an animation of real EEG data.
  5. A filled triangulation on the spheroid.
  6. One frame of an animation of test EEG data (with a monochromatic color map).

Here is an image from the current version of the software (v1.100) which can show 1d animations of data superimposed on the 3d display, and can perform spectral analysis of data using multi-record windowed Fast Fourier Transforms. This composite image shows a single frame of time-series data, the magnitude of the spectrum at a single frequency, and the phase of the spectrum at that frequency. Click on the image for a full-size JPEG:

Here is an image showing a spectrum magnitude at a single frequency, and spectrum cascade plots for two of the sensors. Click on the image for a full-size JPEG:

This software was developed in cooperation between Sky Coyote and Oak Ridge National Laboratory (Dr. Thomas L. Ferrell). It is available free of charge for non-commercial use only.

Prolate1 links:

©Copyright Sky Coyote and Dr. Thomas L. Ferrell, 1998-2002.