Computer simulation of interpolating techniques for generating a realtime EEG potential contour display

This study is concerned with evaluating the feasibility of using hardware adaptable interpolation techniques for approximating the EEG potential field extending over the human scalp. The criteria require that the technique be realizable by analog components and that the approximations be as reliable as that achieved from Bilinear interpolation. A successful interpolation routine would allow the construction of an analog device capable of receiving voltage signals from electrodes and producing a real-time gray-scale contour map of the EEG potential field on a video display screen. A device of this type would be particularly useful in the area of biofeedback research.

A computer program was written to simulate the activity of several interpolation techniques. . Voltage data presented to the program consisted of specific test pattern data and real EEG data records. A TV monitor was used to display the resulting contour maps which were photographed to permit direct image comparisons among the several techniques.

The results show that the Inverse-square radius weighting technique produces images similar to that of the Bilinear, but it contains some undesirable features. The use of a smearing technique substantially reduced these features. The success of the combined Inverse-square and smearing technique and their adaptability to analog components suggest their use in constructing a realtime EEG potential contour display device.