3 nature portfolio  |  reporting summary April 2023 
Materials & experimental systems
n/a Involved in the study
Antibodies
Eukaryotic cell lines
Palaeontology and archaeology
Animals and other organisms
Clinical data
Dual use research of concern
Plants
Methods
n/a Involved in the study
ChIP-seq
Flow cytometry
MRI-based neuroimaging
Magnetic resonance imaging
Experimental design
Design type Structural & Diffusion MRI
Design specifications No task-based fMRI used in this manuscript.
Behavioral performance measures N/A; no performance metrics collected
Acquisition
Imaging type(s) Structural
Field strength 3
Sequence & imaging parameters High-resolution anatomical scans were acquired using a T1-weighted (T1w) magnetization prepared rapid gradient echo 
(MPRAGE) sequence (TR = 2500 ms, TE = 2.31 ms, T1 = 934 ms, flip angle = 7°, 0.8 mm thickness) followed by a gradient 
echo fieldmap (TR = 758 ms; TE1 = 4.92 ms; TE2 = 7.38 ms; flip angle = 60°). A T2-weighted (T2w) turbo spin echo (TSE) 
scan was also acquired with an oblique coronal orientation positioned orthogonally to the main axis of the hippocampus 
(TR/TE = 9860/50 ms, flip angle = 122°, 0.4 × 0.4 mm2 in-plane resolution, 2 mm slice thickness, 38 interleaved slices 
with no gap, total acquisition time = 5:42 min). 
Area of acquisition T1-weighted and dMRI scans = whole-brain  
T2-weighted scan = high-resolution imaging of medial temporal lobe
Diffusion MRI Used Not used
Parameters TR = 4300 ms, echo time = 100.2 ms, 139 directions, b-max = 4990, FoV = 259 x 259 mm, 78 slices, 1.7986 x 1.7986 x 1.8 mm voxel 
resolution
Preprocessing
Preprocessing software Gray Matter Volume & Cortical Thickness: 
Advanced Normalization Tools (ANTs), version 2.1.0 
FreeSurfer, version 7 
 
T2-weighted MTL scans: 
Automatic Segmentation of Hippocampal Subfields (ASHS), version 7/2018 
 
Diffusion imaging: 
QSIprep, version 0.15.3 
DSI Studio, version Chen-2022-07-31 
Normalization Normalization differed by modality due to inherent limitations of applicable processing pipelines. 
 
Gray Matter Volume & Cortical Thickness: 
All analyses were kept in native subject-space to limit the amount of warping and leverage the advantages of a precision 
imaging design.  
 
T2-weighted MTL scans: 
T2w images were registered to the segmentation template (see below) using ANTs deformable registration.  
 
Diffusion imaging:  
Initial preprocessing through QSIprep normalized diffusion images to the skull-stripped T1w images. Diffusion images were 
then reconstructed in MNI space using DSI studio’s Q-space Diffeomorphic Reconstruction.