Figure 3.

Spreading suppression of cortical activation during migraine aura. (A) A drawing showing the progression over 20 min of the scintillations and the visual field defect affecting the left hemifield, as described by the patient (P.R.). The fixation point appears as a small white cross. The red line shows the overall direction of progression of the visual percept. The front of the scintillation at different times within the aura is indicated by a white line. (B) A reconstruction of the same patient's brain (P.R.), based on anatomical MR data. The posterior medial aspect of occipital lobe is shown in an inflated cortex format. In this format, the cortical sulci and gyri appear in darker and lighter gray, respectively, on a computationally inflated surface. MR signal changes over time are shown to the right. Each time course was recorded from one in a sequence of voxels that were sampled along the calcarine sulcus, in the primary visual cortex (V1), from the posterior pole to more anterior location, as indicated by arrowheads. A similar BOLD response was found within all of the extrastriate areas, differing only in the time of onset of the MR perturbation The MR perturbations developed earlier in the foveal representation, compared with more eccentric representations of retinotopic visual cortex. This finding was consistent with the progression of the aura from central to peripheral eccentricities in the corresponding visual field (A and C). (C) The MR maps of retinotopic eccentricity from this same subject, acquired during interictal scans. As shown in the logo in the upper left, voxels that show retinotopically specific activation in the fovea are coded in red (centered at 1.5° eccentricity). Parafoveal eccentricities are shown in blue, and more peripheral eccentricities are shown in green (centered at 3.8° and 10.3°, respectively).