Functional Parcellation of the Human Entorhinal Cortex

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Issue Date
2041-08-01
Language
en
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Abstract
The entorhinal cortex (EC) is the interface between the hippocampus and the neocortex. Since the discov­ery of grid cells in the rodent media! EC, it has been recoguized as a crucial hub for spatial coding and uavigation in rodents. Traditioually, the EC has been subdivided into a media! (MEC) and a lateral (LEC) portion. Postmortem comparative anatomical evidence, however, suggests broader subdivisions amoug ro­deuts, non-human primates and humans. Cytoarchitectonically, up to uine subdivisions of the human EC have been distinguished. Several cytoarchitectonic features also suggest a rnodular arrangement, such as periodic bundliug of pyramidal cell dendrites and axons. Furthennore, tract tracing studies in rodents and non-human primates suggest a wide range of projections along the EC, with media! portions of the EC projecting to the tempora! portion of the hippocampus, while lateral and cauda! portions connected to the septal hippocampus. Differential connectivity pattern of EC subregious could thus lead to distinct intrinsic signa! fluctuations, visible to functioual magnetic resonance imaging (fMRI) at high spatial resolution. How­ever, kuowledge about the fine-graine<l, in-vivo fMRI-based parcellation of the EC has been scarce. Here, we aimed to parcellate the human EC based on its intrinsic signa! fluctuations during a virtual navigation task combined with high-resolution, submillimetre flv1RI at 7T. We generated a functional parcellation of the EC by leveragiug a navel instantaneous correlation analysis approach, termed iustantaneous connectivity parcellation (ICP). The resultiug parcellations showed strong correspondence to topographies fom postmortem cytoarchitectouic studies. These findings allow us to test cormectivity fingerprints of human EC subregions in-vivo and could open up the possibility to iuvestigate neural mechanisms of spatial cognition at an unprecedented level of detail.
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Faculteit der Sociale Wetenschappen