Computational protocol: Greater cerebellar gray matter volume in car drivers: an exploratory voxel-based morphometry study

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Protocol publication

[…] After visually inspecting the structural brain images to exclude data with obvious motion artifact or structural abnormalities from subsequent analysis, we processed the data using the VBM8 toolbox (, which was part of the SPM8 software package ( running on Matlab R2015a (Mathworks Inc., Natick, MA). Essentially, VBM8 image preprocessing includes bias correction, tissue classification, and spatial normalization to the Montreal Neurological Institute space with diffeomorphic anatomical registration through exponentiated Lie algebra. We used the default settings for non-linear modulated VBM, with the exception of the space template of affine regularization, for which we selected the International Consortium for Brain Mapping space template for East Asian brains. This preprocessing produced modulated warped GM images with an isotropic voxel resolution of 1.5 × 1.5 × 1.5 mm. Finally, the modulated warped GM images were smoothed with a 6.0 mm full-width at half-maximum isotropic Gaussian kernel. [...] To disconfirm potentially confounding differences between drivers and non-drivers, we examined group differences in age and questionnaire scores via unpaired t tests. Likewise, group differences in terms of gender were assessed with a chi-square test. For all tests, the level of statistical significance was set at P < 0.05, two-tailed.We conducted a voxel-wise analysis of the between-group difference in GM volume with a general linear model using SPM8. Age was incorporated into the model as a nuisance covariate. To restrict the search volume for analysis, we applied a study population-specific explicit optimal threshold GM mask, created using the Masking toolbox ( The statistical significance level was set at P < 0.05 after family-wise error correction for multiple comparisons in the entire volume of analysis. The results were visualized using the MRIcron software package ( Brain regions showing a significant difference were localized using the Anatomy toolbox ( […]

Pipeline specifications

Software tools SPM, MRIcron
Application Magnetic resonance imaging