Human somatosensory cortical finger representation as studied by combined neuromagnetic and neuroelectric measurements.

We studied somatotopy of human hand somatosensory cortex using evoked responses recorded on magnetoencephalogram (MEG) and scalp-electroencephalogram (EEG) in conjunction with dipole modeling. We found a somatotopic arrangement of cortical digit representations with a sensory sequence from lateral inferior to medial superior in the anatomical order thumb, index finger, middle finger, ring finger, and little finger. MEG alone was able to reproduce this sensory sequence more accurately than scalp-EEG alone. However, the combined information provided by both techniques improved localization accuracy even further. As MEG and scalp-EEG are complementary and confirmatory techniques, this combined approach was useful to get more complete information on the functional organization of human hand somatosensory cortex.