Ultra-high field parallel imaging of the superior parietal lobule during mental maze solving.

Journal article

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.

Authors: Jerde, T; Lewis, S; Goerke, U; Gourtzelidis, P; Tzagarakis, C

• Publication status: Published
• Journal: Experimental brain research
• Volume: 187
• Issue: 4
• Pages: 551-561
• Publication date: 2008-06-01
• DOI: 10.1007/s00221-008-1318-8
• EISSN: 1432-1106
• ISSN: 0014-4819
• Language: English
• Keywords: Magnetic Resonance Imaging; Female; Humans; Cluster Analysis; Parietal Lobe; Brain Mapping; Photic Stimulation; Regression Analysis; Maze Learning; Adult; Male; Oxygen; Image Processing, Computer-Assisted; Analysis of Variance; Mental Processes