Biospin scanner

For the MR images we used a vertical, 40cm bore, 4.7 Tesla, Bruker Biospin scanner. Echo planar images (epi) were acquired for measuring BOLD responses. Every brain volume was acquired in 8 k-space segments (8 shots), with a repetition time of TR = 6 s. The transversal slices were 2 mm thick and the voxel surface varied between sessions ranging from 0.5 to 0.75 mm². Anatomical scans were acquired with FLASH and/or turbo spin echo (RARE) methods with a resolution ranging from 0.25x0.25x2.00 to 0.50x0.50x2.00 mm. fMRI images were corrected for motion artifacts (typically <1 mm), and any linear intensity trend was removed per slice and per voxel. 95% of the voxels had an intensity adjustment of 9% or less from mean intensity (Brainvoyager QX 2.3, Brain Innovation, Maastricht, The Netherlands, [45 (link)]). No spatial smoothing was applied. All subsequent analyzes were performed with Brainvoyager in combination with custom Matlab routines (Matlab 8.3, Mathworks, Natick, MA, USA)

MRI data were acquired with a 9.4T Bruker Biospin scanner equipped with an active-shielded gradient coil, a quadrature volume coil for radiofrequency (RF) excitation, and a single-turn 2 cm diameter surface coil for MR signal reception (Bruker Medizintechnik, Karlsruhe, Germany). High-resolution T2-weighted anatomical images were acquired with the following scan parameters: TR = 2200 ms, TE = 35 ms, field of view (FOV) = 30 × 30 mm², matrix size = 256 × 256, with 25 slices acquired at a slice thickness of 0.6 mm. Functional images were acquired using a single-shot gradient echo-planar imaging (EPI) sequence with the following scan parameters: TR = 1000 ms, TE = 15 ms, FOV = 25 × 15 mm², matrix size = 96 × 58, with 15 slices acquired at a slice thickness of 0.6 mm. Distortions in EPI images were corrected using a reversal k-space strategy⁶⁷ .