Cytoarchitectonic mapping and probabilistic atlas of the human claustrum

Poster Session E - Monday, April 15, 2024, 2:30 – 4:30 pm EDT, Sheraton Hall ABC

Navona Calarco¹ (navona.calarco@mail.utoronto.ca), Olga Kedo², Sebastian Bludau², Christina Herold², Kâmil Uludağ¹, Katrin Amunts²; ¹Medical Biophysics, Faculty of Medicine, University of Toronto, ²Institute of Neuroscience and Medicine, Forschungszentrum Jülich

INTRODUCTION. The claustrum is often described as the brain’s most mysterious nucleus. In large part, the mystery endures because the claustrum’s complex anatomy and proximity to adjacent structures make it difficult to resolve at resolutions typical of in vivo MRI. Here, we create a high-resolution, three-dimensional, probabilistic, cytoarchitectonic reference atlas of the claustrum, to advance investigation in living humans. METHODS. We mapped the claustrum according to apparent anatomy in 10 postmortem brains (5 female, ages 37-85), on Merker-stained coronal sections at 1 micron in-plane resolution (distance between sections = <1.2mm). Then, we reconstructed the claustrum in three-dimensions, and computed probabilistic maps in interoperable MRI reference spaces, at 1mm isotropic resolution. RESULTS. The high-resolution delineation, in both hemispheres, and across multiple brains, allowed a thorough characterization of the claustrum’s structure, whilst underscoring the inherent difficulty of claustral investigation in vivo. We observed extraordinary heterogeneity in cytoarchitecture across the claustrum’s extent, and found that the claustrum directly abuts the olfactory tubercles, amygdaloidal complex, and the piriform cortex: surpassing what is denoted by other high-resolution atlases. Our probabilistic maps revealed a high degree of intersubject variability, especially in the claustrum’s ventral extension into the temporal lobe. CONCLUSIONS. Ours is the first three-dimensional cytoarchitectonic reference of the human claustrum, based on the analysis of multiple brains. Alongside advances in MRI resolution, this reference holds significant potential to illuminate claustral structure-function relationships, by reducing misattribution of function to adjacent structures. The probabilistic maps will be integrated into the Julich Brain Atlas.

Topic Area: NEUROANATOMY