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@INPROCEEDINGS{Kedo:1048413,
author = {Kedo, Olga and Lothmann, Kimberley and Schiffer, Christian
and Mohlberg, Hartmut and Dickscheid, Timo and Amunts,
Katrin},
title = {{T}he hippocampal formation mapped in the {B}ig{B}rain:
{T}he deep-learning supported high-resolution mapping and
3{D} reconstruction},
reportid = {FZJ-2025-04624},
year = {2025},
abstract = {The hippocampal formation (HF) plays a pivotal role in
different aspects of memory, with its subdivisions having
various functional implications. The hippocampus has been
parcellated in different ways both in histological and MRI
studies [1, 2]. In the BigBrain, 3D rendering of the
hippocampus was performed with its subdivisions being
revealed through unfolding and unsupervised clustering of
laminar and morphological features [3]. However, this
parcellation was not detailed enough, e.g. in the field of
the subicular complex (subiculum).We cytoarchitectonically
identified and mapped in 10 postmortem brains and generated
probabilistic maps of CA1, CA2, CA3, CA4, Fascia dentata
(FD), prosubiculum (ProS), subiculum (Sub), presubiculum
(PreS), parasubiculum (PaS), transsubiculum (TrS),
hippocampal-amygdaloid transition area (HATA) and entorhinal
cortex (EC) [4]. Based on this research, we mapped HF in the
BigBrain and generated the 3D maps of HF in the BigBrain
template. Cytoarchitectonic mapping of 12 structures was
performed in at least each 15th serial histological sections
in the web-based annotation tool MicroDraw at 1-micron
resolution in-plane in the BigBrain. Subsequently, a Deep
Learning Workflow was utilized to 3D-reconstruct the
structures. Convolutional Neural Networks were trained for
image segmentation in the sections lying between those
manually mapped using ATLaSUI [5]. The annotations of each
structure were non-linearly transformed to the sections of
the 3D reconstructed BigBrain space at 20-micron isotropic
resolution [6], and was further visualized using the
Neuroglancer.We have identified 12 cytoarchitectonic
structures of HF in the BigBrain and analyzed their
macroanatomy (Fig. 1). Fasciola cinerea (FD in its
mediocaudal extension) was larger in the left hemisphere,
while it was minuscule on the right (Fig.1A). Left ProS
extended onto dorsomedial surface of the parahippocampal
gyrus (PHG), while the right ProS almost does not appear on
the surface (Fig.1B). Caudally, PreS occupied medial surface
of the PHG. TrS abutted on PreS ventrally. Caudal TrS
bordered the temporo-parieto-occipital proisocortex
laterally (Fig.1A), while rostral TrS abutted upon area 35.
PaS replaced TrS rostrally. The detailed mapping of HF
reflected a transition from the allocortex (ProS and Sub) to
the periallocortex (PreS, PaS) within the subicular complex
that traditionally was considered as a cytoarchitectonic
unit. Rostrally, both hemispheres had three Digitationes
hippocampi respectively (Fig.1C). The high-resolution (20
μm) whole-brain histological references of HF were
generated on the basis of the BigBrain. They will be
publicly available on the EBRAINS platform and integrated
with the BigBrain model, extending maps of the piriform
cortex [7] to represent two hubs of limbic system [8].1.
Wisse L.E.M. et al. (2017) Hippocampus, 27(1): p. 3-11.2.
Yushkevich P.A. et al. (2015), Neuroimage, 111: p. 526-41.3.
DeKraker J. et al. (2020), Neuroimage, 206: p. 116328.4.
Palomero-Gallagher N. et al. (2020), Brain Struct Funct,
225(3): p. 881-907.5. Schiffer C. et al. (2021), Neuroimage,
240: p. 118327.6. Amunts K. et al. (2013), Science,
340(6139): p. 1472-5.7. Kedo O. et al. (2024), Anatomia,
3(2): p. 68–92.8. Catani M. et al. (2013), Neurosci
Biobehav Rev, 2013. 37(8): p. 1724-37.},
month = {Oct},
date = {2025-10-27},
organization = {9th BigBrain Workshop -HIBALL Closing
Symposium, Berlin (Germany), 27 Oct
2025 - 29 Oct 2025},
subtyp = {After Call},
cin = {INM-1},
cid = {I:(DE-Juel1)INM-1-20090406},
pnm = {5251 - Multilevel Brain Organization and Variability
(POF4-525) / HIBALL - Helmholtz International BigBrain
Analytics and Learning Laboratory (HIBALL) (InterLabs-0015)},
pid = {G:(DE-HGF)POF4-5251 / G:(DE-HGF)InterLabs-0015},
typ = {PUB:(DE-HGF)24},
url = {https://juser.fz-juelich.de/record/1048413},
}