2.5 fMRI data acquisition and processing
All images were acquired through a 3.0-T Phillips Achieva DS scanner
(Philips Medical Systems, Best, the Netherlands) with a 32-channel head
coil. First, a T1-3D anatomical scan (TR/TE 8.2/3.8; matrix 240x240;
1x1x1 mm3 voxel; transverse slices) was taken. During the cue-reactivity
task, echo planar images (EPIs) covering the whole brain were taken with
a total of 36 ascending axial slices (3x3x3 mm3 voxel size; slice gap
3mm; TR/TE 1.999/28ms; matrix 80x80).
The MRI data was preprocessed using the fMRI prep 1.3.2 pipeline(Estebanet al. , 2019). First, the anatomical data was corrected for
intensity nonuniformity, skull-stripped, spatially normalized, and
segmented into cerebrospinal fluid, white matter, and gray matter.
Second, the functional data was corrected for susceptibility distortions
by using a deformation field followed by co-registration,
motion-correction, and smoothing. Third, an independent component
analysis for Automatic Removal of Motion Artifacts (ICA-AROMA)(Pruimet al. , 2015) was performed that automatically removed (head)
motion artifacts and the data was resampled to standard space.
The current study utilized SPM12 to further analyze the fMRI data
(http://www.fil.ion.ucl.ac.uk/spm). First level models included
separate regressors for the cocaine clue block, the emotionally negative
block, and the two neutral blocks. These regressors were convolved with
a canonical hemodynamic response function. A high pass filter (1/128 Hz)
was included in the first-level model to correct for low-frequency
signal drift. The contrasts for the neutral, emotionally negative and
cocaine blocks were subsequently entered in a second level model.
Subsequently, the Marsbar toolbox (http://marsbar.sourceforge.net)
was used to extract the mean activity for the contrasts for each region
of interest (DS, VS, amygdala and dACC). In line with previous research
, the VS was defined as the nucleus accumbens from the Harvard-Oxford
subcortical structure probability atlas
(http://www.cma.mgh.harvard.edu/fsl_atlas.html) and the DS was
defined as the caudate and putamen from the automated anatomical
labeling (AAL) atlas(Tzourio-Mazoyer et al. , 2002) minus the VS.
The dACC was defined as the higher (z-coordinate> 78) part
of the ACC defined by the AAL atlas. Finally, the amygdala mask was
derived from the AAL atlas.