Retinotopic mapping of the human visual cortex at a magnetic field strength of 7 T

ObjectivefMRI-based retinotopic mapping data obtained at a magnetic field strength of 7 T are evaluated and compared to 3 T acquisitions.MethodsWith established techniques retinotopic mapping data were obtained in four subjects for 25 slices parallel to the calcarine sulcus at 7 and 3 T for three voxel sizes (2.53, 1.43, and 1.13 mm3) and in two subjects for 49 slices at 7 T for 2.53 mm3 voxels. The data were projected to the flattened representation of T1 weighted images acquired at 3 T.ResultsThe obtained retinotopic maps allowed for the identification of visual areas in the occipito-parietal cortex. The mean coherence increased with magnetic field strength and with voxel size. At 7 T, the occipital cortex could be sampled with high sensitivity in a short single session at high resolution. Alternatively, at lower resolution simultaneous mapping of a great expanse of occipito-parietal cortex was possible.ConclusionRetinotopic mapping at 7 T aids a detailed description of the visual areas. Here, recent findings of multiple stimulus-driven retinotopic maps along the intraparietal sulcus are supported.SignificanceRetinotopic mapping at 7 T opens the possibility to detail our understanding of the cortical visual field representations in general and of their plasticity in visual system pathologies.