Ultra-high field parallel imaging of the superior parietal lobule during mental maze solving.
We used ultra-high field (7 T) fMRI and parallel imaging to scan the superior parietal lobule (SPL) of human subjects as they mentally traversed a maze path in one of four directions (up, down, left, right). A counterbalanced design for maze presentation and a quasi-isotropic voxel (1.46 x 1.46 x 2 mm thick) collection were implemented. Fifty-one percent of single voxels in the SPL were tuned to the direction of the maze path. Tuned voxels were distributed throughout the SPL, bilaterally. A nearest neighbor analysis revealed a "honeycomb" arrangement such that voxels tuned to a particular direction tended to occur in clusters. Three-dimensional (3D) directional clusters were identified in SPL as oriented centroids traversing the cortical depth. There were 13 same-direction clusters per hemisphere containing 22 voxels per cluster, on the average; the mean nearest-neighbor, same-direction intercluster distance was 9.4 mm. These results provide a much finer detail of the directional tuning in SPL, as compared to those obtained previously at 4 T (Gourtzelidis et al. Exp Brain Res 165:273-282, 2005). The more accurate estimates of quantitative clustering parameters in 3D brain space in this study were made possible by the higher signal-to-noise and contrast-to-noise ratios afforded by the higher magnetic field of 7 T as well as the quasi-isotropic design of voxel data collection.
Jerde
Trenton A
TA
Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, Minneapolis, MN 55455, USA.
Lewis
Scott M
SM
Goerke
Ute
U
Gourtzelidis
Pavlos
P
Tzagarakis
Charidimos
C
Lynch
Joshua
J
Moeller
Steen
S
Van de Moortele
Pierre-François
PF
Adriany
Gregor
G
Trangle
Jeran
J
Uğurbil
Kâmil
K
Georgopoulos
Apostolos P
AP
D000328:Adult; D000704:Analysis of Variance; D001931:Brain Mapping; D016000:Cluster Analysis; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D018782:Maze Learning / Q000502:physiology*; D008606:Mental Processes / Q000502:physiology*; D010100:Oxygen / Q000097:blood; D010296:Parietal Lobe / Q000098:blood supply* / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D012044:Regression Analysis
D010100:Oxygen