title: Retinotopic mapping of the human visual cortex at a magnetic field strength of 7T.
abstract: OBJECTIVE
  fMRI-based retinotopic mapping data obtained at a magnetic field strength of 7T are evaluated and compared to 3T acquisitions.
  
  
  METHODS
  With established techniques retinotopic mapping data were obtained in four subjects for 25 slices parallel to the calcarine sulcus at 7 and 3T for three voxel sizes (2.5(3), 1.4(3), and 1.1(3)mm(3)) and in two subjects for 49 slices at 7T for 2.5(3)mm(3) voxels. The data were projected to the flattened representation of T1 weighted images acquired at 3T.
  
  
  RESULTS
  The 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 7T, 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.
  
  
  CONCLUSIONS
  Retinotopic mapping at 7T aids a detailed description of the visual areas. Here, recent findings of multiple stimulus-driven retinotopic maps along the intraparietal sulcus are supported.
  
  
  CONCLUSIONS
  Retinotopic mapping at 7T opens the possibility to detail our understanding of the cortical visual field representations in general and of their plasticity in visual system pathologies.
authors.affiliation: Visual Processing Laboratory, Department of Ophthalmology, Otto-von-Guericke University Magdeburg, Leipziger Strasse 44, 39120 Magdeburg, Germany. michael.hoffmann@med.ovgu.de
authors.forename: Michael B
authors.initials: MB
authors.lastname: Hoffmann
authors.forename: Jörg
authors.initials: J
authors.lastname: Stadler
authors.forename: Martin
authors.initials: M
authors.lastname: Kanowski
authors.forename: Oliver
authors.initials: O
authors.lastname: Speck
mesh_terms: D000328:Adult; D001931:Brain Mapping; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D010100:Oxygen / Q000097:blood; D010364:Pattern Recognition, Visual; D010775:Photic Stimulation / Q000379:methods; D011930:Reaction Time; D012160:Retina / Q000502:physiology*; D014793:Visual Cortex / Q000098:blood supply / Q000502:physiology*; D014794:Visual Fields; D014795:Visual Pathways / Q000098:blood supply / Q000502:physiology; D055815:Young Adult
chemical_list: D010100:Oxygen