Computational protocol: Hippocampal volume correlates with attenuated negative psychotic symptoms irrespective of antidepressant medication

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Protocol publication

[…] Structural MRI data were analyzed using the voxel-based morphometry toolbox (VBM8, http://dbm.neuro.uni-jena.de/vbm8/), implemented within SPM8 (Wellcome Department of Cognitive Neurology, London, UK) and running on Matlab 7.11 (MathWorks, USA). All T1-weighted images were first checked for scanner artifacts and anatomical abnormalities. Images were then segmented into gray matter, white matter and cerebrospinal fluid using the adaptive maximum a posteriori technique (in contrast to the classical use of a priori Tissue Probability Maps), where local variations in the parameters are modeled by means of slowly varying spatial functions (). More accurate segmentation can be achieved with partial volume estimation of additional mixed tissue classes in every voxel. All images were DARTEL-normalized (Diffeomorphic Anatomical Registration using Exponentiated Lie algebra; ). The DARTEL template was derived from 550 healthy controls as provided in MNI space. This method produces more accurate results for registration and additional registration in MNI space was unnecessary (). Finally, sample homogeneity was reviewed and all images were smoothed using an isotropic 8 mm full-width-at-half-maximum (FWHM) Gaussian kernel ().Group differences were explored using a one-way ANOVA. Since our groups differed significantly in gender and age, we introduced these two variables as additional covariates of interest. Group comparisons included ARMS-AD versus ARMS-nonAD versus healthy controls. Brain region labeling was achieved using the Harvard–Oxford structural atlas (http://fsl.fmrib.ox.ac.uk/fsl/fslwiki/Atlases ()), incorporated within the FMRIB Software Library (FSL).Statistical significance was assessed at a cluster level using a threshold of p < 0.005 uncorrected (cluster-forming threshold); statistical inference was then made at p < 0.05, adjusted to provide a family-wise error (FWE) correction at the peak and cluster levels. […]

Pipeline specifications

Software tools SPM, FSL
Application Magnetic resonance imaging
Diseases Alzheimer Disease, Brain Diseases, Brain Injuries, Psychoses, Substance-Induced