Multichannel PC-based data-acquisition system for high-resolution EEG

Describes a complete, high-performance data-acquisition system for high-resolution EEG. The system includes preamplified EEG electrodes, rigid helmets, differential instrumentation and software-controlled gain amplifiers, digitizing and control circuitry, and optical coupling to a 486 PC. Miniaturized preamplifiers mounted on individual electrodes reduce coupling to external electromagnetic fields and minimize signal distortion caused by increased and/or imbalanced electrode impedances. Electrodes are applied quickly and with minimal skin preparation, yet with high packing densities and repositioning consistent to about 1-3 mm in repeated applications. Extensive testing under realistic conditions demonstrates that the system provides superior electrical performance compared to currently available commercial systems.