Structural connectivity-based segmentation of the human entorhinal cortex

Abstract

The medial (MEC) and lateral entorhinal cortex (LEC), widely studied in rodents, are well defined and characterized. In humans, however, the exact locations of their homologues remain uncertain. Previous functional magnetic resonance imaging (fMRI) studies have subdivided the human EC into posteromedial (pmEC) and anterolateral (alEC) parts, but uncertainty remains about the choice of imaging modality and seed regions, in particular in light of a substantial revision of the classical model of EC connectivity based on novel insights from rodent anatomy. Here, we used structural, not functional imaging, namely diffusion tensor imaging (DTI) and probabilistic tractography to segment the human EC based on differential connectivity to other brain regions known to project selectively to MEC or LEC. We defined MEC as more strongly connected with presubiculum and retrosplenial cortex (RSC), and LEC as more strongly connected with distal CA1 and proximal subiculum (dCA1pSub) and lateral orbitofrontal cortex (OFC). Although our DTI segmentation had a larger medial-lateral component than in the previous fMRI studies, our results show that the human MEC and LEC homologues have a border oriented both towards the posterior-anterior and medial-lateral axes, supporting the differentiation between pmEC and alEC.

Transversal functional connectivity and scene-specific processing in the human entorhinal-hippocampal circuitry

“…These findings provide clear evidence for a hypothesized transversal difference in scene information processing within the human subiculum. Our data also replicate the earlier functional and structural connectivity reports in humans as well as anatomical findings of a route between posterior-medial EC (based on parahippocampal connectivity) and distal subiculum ( Maass et al, 2015 ; Syversen et al, 2021 ; Witter et al, 2000 ). The scene information processing bias has mainly been previously reported for the EC (in rodents, operationalized by spatial processing conditions: Neunuebel et al, 2013 ; Keene et al, 2016 ; in humans, operationalized by scene stimulus conditions: Berron et al, 2018 ; Navarro Schröder et al, 2015 ; Reagh and Yassa, 2014 ; Schultz et al, 2015 ).…”

“…On one hand, rodent research indicates a transversal organization where scene and object information is processed along two anatomically wired routes, the medial EC – distal subiculum – proximal CA1 route and the lateral EC – proximal subiculum – distal CA1 route, respectively ( Witter et al, 2017 ; note sparse functional evidence in the subiculum: Ku et al, 2017 ; Cembrowski et al, 2018 ; but frequent reports in the rodent CA1 region: Henriksen et al, 2010 ; Nakamura et al, 2013 ; Igarashi et al, 2014 ; Nakazawa et al, 2016 ; Beer et al, 2018 ). Initial functional and structural connectivity data also indicate such a transversal connectivity profile in humans ( Maass et al, 2015 ; Syversen et al, 2021 ). In accordance, scene information seems to be preferentially processed in the distal subiculum ( Dalton et al, 2018 ; Dalton and Maguire, 2017 ; Zeidman et al, 2015 ) and hints exist for preferential object processing at the subiculum/CA1 border ( Dalton et al, 2018 ).…”

A framework For brain atlases: Lessons from seizure dynamics

“…During the course of conducting this study, and while undergoing peer review, other atlases with more accurate or relevant parcellations to the study’s population were published in different areas of neuroscience( Callaway et al, 2021 ; Doucet et al, 2021 ; Huang et al, 2021 ; Joglekar et al, 2021 ; Lewis et al, 2021 ; Muñoz-Castañeda et al, 2021 ; 2021 ; Syversen et al, 2021 ; Wang et al, 2021 ; Zhu et al, 2021 ). Here, we cautiously propose a question: Are efforts to publish more atlases created with different algorithms or slightly modified parcellations from existing atlases providing any advantages over already existing atlases?…”

Comprehensive Cortical Structural Features Predict the Efficacy of Cognitive Behavioral Therapy in Obsessive-Compulsive Disorder

“…The entorhinal cortex (EC), located in the medial temporal lobe, is the central structure of memory formation and navigation. Traditionally, it has been regarded as a hub for information transmission and processing from the neocortex to the hippocampus [ 37 ]. One study, exploring the cortical morphological networks using cortical thickness, sulcal depth and surface area, found that the entorhinal cortex acts as a morphological ‘hub’ in the network [ 38 ].…”