Suppression of interference and artifacts by the Signal Space Separation Method.

Multichannel measurement with hundreds of channels oversamples a curl-free vector field, like the magnetic field in a volume free of sources. This is based on the constraint caused by the Laplace's equation for the magnetic scalar potential; outside of the source volume the signals are spatially band limited. A functional solution of Laplace's equation enables one to separate the signals arising from the sphere enclosing the interesting sources, e.

Neuromagnetic somatosensory responses to natural moving tactile stimulation.

Objective: To explore the somatosensory cortical responses to natural moving tactile stimulation in adult subjects using magnetoencephalography.

Methods: We measured cortical somatosensory magnetic evoked fields (SEFs) to moving tactile stimuli by a brush over the right thumb once every 1.5 s in seven subjects.