Figure 2

An example of coregistration of MEG and electrophysiological signals. Amira software was used to digitally reconstruct and "reslice" both MRI and histological sections, such that the locations of MEG signal sources and electrophysiological recording data could be identified with precision. A, C, E, Sagittal, horizontal, and coronal views, respectively, obtained using MRI in Case 24056. The yellow dot indicates the signal source identified using MEG. Blue, magenta, and green lines in panels A and B indicate planes of section shown in panels C-H. B, D, F: Sagittal, horizontal, and coronal views, respectively, that were digitally reconstructed from block face images obtained during histological sectioning of the brain. G: Horizontal view of the brain in Case 24056, digitally reconstructed from MRI data. Note that this plane of section matches the plane of section used for histological sectioning shown in panel H. H: Block face image of the brain taken during histological sectioning. The white box in panel H indicates the location of the photomicrograph shown in I. Arrowheads in panels B, D, F, and H indicate a single electrode track from recordings in the same location as the signal source identified using MEG. I: Digital photomicrograph of the section adjacent to the block face image shown in panel H, reacted for cytochrome oxidase. Asterisks indicate penetrations at which the receptive fields shown in panel J were obtained. The receptive fields at recordings in this location were identical for both MEG and electrophysiological recordings. The location of this penetration corresponds to the signal source identified using MEG. Digitally "resectioning" the MEG and histological data allowed us to match these data sets with high fidelity. Banding pattern in panels B, D, and F is due to lighting variations during photography of individual block face images.