Data collected by a transcranial brain function measuring/stimulating method is accurately projected and displayed onto a brain surface. If there is no three-dimensional head image, data is projected and displayed onto the brain surface of a standard brain. The head surface coordinates are transformed to the brain surface coordinates of the brain surface underlying the head surface by, e.g., a minimum distance search method. The coordinates of a projected point on the brain surface of the head surface and the probability distribution are determined for a standard brain normalized with data on subjects.
Method for transforming head surface coordinates to brain surface coordinates and transcranial brain function measuring method using the transformation data