Human visual motion areas determined individually by magnetoencephalography and 3D magnetic resonance imaging

We used magnetoencephalography to study inter-individual locational differe nce in the extrastriate region which responds to visual motion. Magnetic re sponses to visual motion onset from the right temporo-occipital area were r ecorded from 12 subjects. All the subjects had clear responses to apparent or random dot coherent motion. The origins of these responses was investiga ted by use of the single equivalent current dipole model. The nearest scalp to the origin also was identified for each subject, which may be useful in transcranial stimulation studies. Although the magnetic responses of all t he subjects should have the same functional properties; be related to neura l activities synchronized exclusively to the onset of motion, the estimated origins varied greatly among the subjects. The location of origin could be classified as one of three types: temporo-occipital, occipital, or parieta l, according to the sulcal anatomy investigated in the individual's three-d imensional magnetic resonance image. Temporo-occipital types were found for seven subjects, and anatomically the regions were around human MT/V5. Two subjects had the occipital type, with regions posterior to the anatomical M T/V5 and corresponding to V3A anatomically. The other three subjects had or igins classified as the parietal type dorso-rostral to the anatomical MT/V5 , with regions around the posterior end of the superior temporal sulcus. Al though all these cortical regions appear to be related to the neural proces s of visual motion, whether they correspond functionally to the same names or migrated MT/V5 must now be determined. Hum. Brain Mapping 11: 33-45, 200 0. (C) 2000 Wiley-Liss, Inc.