The volume of the right brain hemisphere, white matter, and grey matter were measured by MRI as previously described (Henriksen et al., 2022a (link)). Briefly, the entire right hemisphere was immersed in 4% paraformaldehyde in phosphate buffered saline for 24 h at 4°C (PBS; 0.1 M, pH 7.4), rehydrated with PBS for 24 h at 4°C and washed twice with Fomblin (perfluoro-polyether; Solvay, Princeton, New Jersey, USA) to remove the excess fluid and resubmerged in clean Fomblin prior to scanning. It was confirmed that there was no surrounding fluid signal on the surface of each brain before high-resolution imaging. Data was acquired with a 9.4 Tesla preclinical scanner (Bruker BioSpin, Ettlingen, Germany) equipped with a 240 mT/m gradient coil (BGA-12S, Bruker) and using an 86-mm inner diameter transmit-receive volume coil. The imaging protocol used a 3D gradient-spoiled steady state free precession, and the parameters were set to: repetition time = 4.6 ms, echo time = 2.3 ms, number of signals averaged = 10, flip angle = 25°, field of view = 60 mm × 38.4 mm × 25.6 mm, matrix = 300 × 192 × 128, image resolution = 200 μm isotropic, acquisition time = 20 min. The images were bias-field corrected, and segmented as previously described (Henriksen et al., 2022a (link)). The volume of white and grey matter was normalized to the total volume of the brain hemisphere.
Free full text: Click here
