Analysis of fMRI data
Data were analysed using FSL (FMRIB Software Library v6.05; Pre-processing of each participant’s functional data was done with FEAT (FMRI Expert Analysis Tool), part of FSL. This included motion correction using MCFLIRT (Jenkinson et al. Regarding the ER task, lower-level analysis was carried out to observe within-subject differences in brain activity across the two conditions by including the following contrasts: (1) maintain vs. baseline (M>B) to identify brain regions active when asked to naturally experience the emotion elicited; (2) reappraise vs. baseline (R>B) to identify brain regions active during voluntary suppression of negative affect using reappraisal techniques; (3) reappraise vs. maintain (R>M) to identify brain regions with greater activation when reappraising as compared to maintain; (4) maintain vs. reappraise (M>R) to identify brain regions with greater activation whilst maintaining as compared to reappraise; and (3) overall picture blocks vs. baseline (M+R>B), to identify brain regions activated in response to negative images.A custom 3-column format convolved with a gamma haemodynamic response function and its temporal derivative were used to model the data. Time-series statistical analysis was carried out using FILM with local autocorrelation correction (Woolrich et al. In the higher-level analysis for the ER task, the contrast of parameter estimates (COPEs), their variance (VARCOPEs) and DOFs from the lower-level analysis were introduced into the analysis. Using a mixed-effects analysis with FLAME1+2 across the whole brain, the following contrasts were analysed: (1) placebo>lithium (1, −1); (2) lithium>placebo (−1, 1); and (3) mean activation and deactivation across both treatment groups (1, 1; −1, −1). Due to lithium’s potential to promote GM changes, GM images of each participant were extracted using FMRIB’s Automated Segmentation tool (Zhang et al. Small volume correction (SVC) analysis was performed using several regions of interests (ROIs) known to be involved in emotional processing and cognitive reappraisal focused on the amygdala, vmPFC, vlPFC, and middle temporal gyrus (MTG). Bilateral amygdala’s anatomical masks were created using the probabilistic map thresholded at 50 provided by the Harvard-Oxford Structural Atlas in FSL. Spherical masks of 10-mm radius were created for the bilateral vmPFC, vlPFc, and MTG using coordinates previously reported (Buhle et al. Exploratory connectivity analysis was performed to investigate a seed ROIs’ relationship with other brain areas throughout the task using psychophysiological interactions analysis in FSL (O’Reilly et al. 