Paul E. Rasser (1,2), Pat Johnston (1,3), Jim Lagopoulos (1,2), Philip B. Ward (1,2), Ulli Schall (1,3), Renate Thienel (1,4), Stefan Bender (1,4), and Paul M. Thompson (1,5)
(1) Neuroscience Institute of Schizophrenia and Allied Disorders (NISAD), Australia
(2) Department of Psychiatry, University of New South Wales, Australia
(3) Centre for Mental Health Studies, University of Newcastle, Australia
(4) Clinic for Psychiatry, University of Essen, Germany
(5) Laboratory of Neuro Imaging, UCLA School of Medicine, USA
We tested the hypothesis that novel cortical surface modelling approaches can permit more accurate localisation of functional deficits in schizophrenia, and more sharply defined activation foci. We created two average models of cerebral cortex from 3D structural magnetic resonance images (sMRI) of 10 first-episode male patients with schizophrenia and 10 age- and sex-matched controls. 3D functional magnetic resonance imaging (fMRI) BOLD activation data, obtained while subjects performed the ĎTower of Londoní task, was then mapped to both cortex models for comparison across diagnostic groups (patient and control) and between cortical alignment methods.
The first average cortical model was created by identifying 17 sulci on each hemisphere of each subjectís brain. These sulci were geometrically averaged, and each subjectís cortex warped into alignment with the average sulci. The second average cortical model of cortex was developed by aligning individual sMRIs to a template, intensity averaging, and extracting the cortex from the resulting average image.
fMRI data showed increased activation with task difficulty in the control group in the left Brodmannís areas 44, 7, 37, and 18 and in the right Brodmannís area 7. In the patient group, increased activation with task difficulty was seen in the left Brodmannís area 10 and in the right Brodmannís area 18. Significantlydecreased activation with task difficulty was found in the left and right Brodmannís area 9 of the patient group; this was not observed in the control group.
Sulcal averaging and cortical data warping resulted in sharper localisation of the functional data when compared to the functional data mapped to the cortical model derived from an average intensity brain.
Future comparisons will relate these functional differences to differences in cortical grey matter density in patients and controls.
Paul Thompson, Ph.D.
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