The high degree of intersubject structural variability in the human brain is an obstacle in combining data across subjects in functional neuroimaging experiments. A common method for aligning individual data is normalization into standard 3D stereotaxic space. Since the inherent geometry of the cortex is that of a 2D sheet, higher precision can potentially be achieved if the intersubject alignment is based on landmarks in this 2D space. To examine the potential advantage of surface-based alignment for localization of auditory cortex activation, and to obtain high-resolution maps of areas activated by speech sounds, fMRI data were analyzed from the left hemisphere of subjects tested with phoneme and tone discrimination tasks. We compared Talairach stereotaxic normalization with two surface-based methods: Landmark Based Warping, in which landmarks in the auditory cortex were chosen manually, and Automated Spherical Warping, in which hemispheres were aligned automatically based on spherical representations of individual and average brains. Examination of group maps generated with these alignment methods revealed superiority of the surface-based alignment in providing precise localization of functional foci and in avoiding mis-registration due to intersubject anatomical variability. Human left hemisphere cortical areas engaged in complex auditory perception appear to lie on the superior temporal gyrus, the dorsal bank of the superior temporal sulcus, and the lateral third of Heschl's gyrus.
Bibliographical noteFunding Information:
This work was supported by National Institute of Deafness and Communication Disorders grant R01 DC006287 (EL), National Institute of Neurological Diseases and Stroke grant R01 NS33576 (JB), and National Institutes of Health General Clinical Research Center grant M01 RR00058 (JB). We thank David Van Essen, John Harwell, Donna Hanlon, Ziad Saad, Rick Reynolds, Brenna Argall, Bruce Fischl, Doug Greve, and Jon Wieser for their assistance with many technical issues.
Copyright 2008 Elsevier B.V., All rights reserved.
- Auditory cortex
- Surface-based alignment
- Talairach normalization