Computational protocol: Increased Amygdala and Visual Cortex Activity and Functional Connectivity towards Stimulus Novelty Is Associated with State Anxiety

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Protocol publication

[…] The images were visually inspected for signal dropout in the amygdala as this area is somewhat prone to magnetic susceptibility. However, none of our subjects had to be excluded due to signal dropout. The functional MRI data were pre-processed and analysed using the SPM8 software package (http://www.fil.ion.ucl.ac.uk/spm). All volumes were realigned to the first volume in the time series to correct for head motion . One subject was excluded due to excessive head movements during the scan (cut off>3 mm). Subsequently, the mean functional image and the anatomical image were coregistered to ensure they were aligned. The images were spatially normalised to the Montreal Neurological Institute (MNI) template , resampled to 2×2×2 mm voxels and smoothed using a 6 mm full width-half maximum (FWHM) isotropic kernel. Data were high-pass filtered using a cut-off value of 128 s. To test for the effect of emotional novelty, we defined three event types; 1st presentation (20 trials), 2nd presentation (20 trials) and other presentations (consisting of the 3rd–6th presentation trials, 29 trials in total). The model was specified by stick functions for the onsets of the three different event types, and convolved with a canonical hemodynamic response function. The contrasts of interest were “1st presentation” > “2nd presentation” and “2nd presentation” > “other presentations”. For completeness, we also contrasted “1st presentation” > “other presentations”. The individual contrast images were moved up to a second-level random effects model. Both the inferior occipital gyrus (IOG) and the fusiform gyrus (FFG) constitute key nodes in the face perception network , , and were therefore chosen as our a priori regions of interest in addition to the amygdala. Consequently, we used small volume correction (pFWE = 0.05) based on anatomically defined (Automated anatomical labelling (aal) atlas in the SPM Wake Forest University (WFU) PickAtlas toolbox (http://fmri.wfubmc.edu/software/PickAtlas) ) bilateral IOG, FFG and the amygdala.To identify regions where activity correlated with individual state anxiety scores, a second–level, linear regression model specifying the individual novelty responses (“1st presentation” > “2nd presentation”) and the log transformed STAI state anxiety scores as a covariate were used. Due to the consistent association between amygdala responsivity to threat-related stimuli and individual differences in state anxiety , , amygdala was our a priori region of interest. Thus we applied small volume correction (pFWE = 0.05) based on anatomically defined (WFU Pickatlas; ) bilateral amygdala. […]

Pipeline specifications

Software tools SPM, AAL
Applications Magnetic resonance imaging, Functional magnetic resonance imaging
Organisms Homo sapiens