The mesiotemporal lobe (MTL) is implicated in many cognitive processes, is compromised in numerous brain disorders, and exhibits a gradual cytoarchitectural transition from six-layered parahippocampal isocortex to three-layered hippocampal allocortex. Leveraging an ultra-high-resolution histological reconstruction of a human brain, our study showed that the dominant axis of MTL cytoarchitectural differentiation follows the iso-to-allocortical transition and depth-specific variations in neuronal density. Projecting the histology-derived MTL model to in-vivo functional MRI, we furthermore determined how its cytoarchitecture underpins its intrinsic effective connectivity and association to large-scale networks. Here, the cytoarchitectural gradient was found to underpin intrinsic effective connectivity of the MTL, but patterns differed along the anterior-posterior axis. Moreover, while the iso-to-allocortical gradient parametrically represented the multiple-demand relative to task-negative networks, anterior-posterior gradients represented transmodal versus unimodal networks. Our findings establish that the combination of micro- and macrostructural features allow the MTL to represent dominant motifs of whole-brain functional organization.
Code and data related to this specific project are openly available under https://github.com/MICA-MNI/micaopen/tree/master/cortical_confluence, BigBrain related information are openly available under https://bigbrain.loris.ca/main.php. The human connectome project dataset is available under https://db.humanconnectome.org/.
- Boris Bernhardt
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Human subjects: Participants gave informed consent and the study was approved by the local Research Ethics Board of the Montreal Neurological Institute and Hospital (2018-3469).
- Morgan Barense, University of Toronto, Canada
© 2020, Paquola et al.
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