Topographical brain electrical activity mapping on an IBM-compatible personal computer.

A new system for computing brain electrical activity maps on a standard IBM-compatible computer has been developed. The EEG is recorded using a CED1401 intelligent laboratory interface and stored in the computer; colour coded maps are generated using software developed in Turbo PASCAL and displayed on the EGA graphics screen. An acceptable computation time of 1.2 s for a 64 x 64 map displayed as a 128 x 128 pixel image has been achieved by incorporating assembly language routines and a maths coprocessor. The system may be readily upgraded as improved hardware becomes available and further software can be added. In addition to triggering auditory, visual and somatosensory stimulators, it provides the potential for the generation of complex stimuli for cognitive experiments by means of mass RAM and digital-to-analogue converters.