AUTHOR=Behroozi Mehdi , Graïc Jean-Marie , Gerussi Tommaso 

TITLE=Beyond the surface: how ex-vivo diffusion-weighted imaging reveals large animal brain microstructure and connectivity

JOURNAL=Frontiers in Neuroscience

VOLUME=18

YEAR=2024

URL=https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2024.1411982

DOI=10.3389/fnins.2024.1411982

ISSN=1662-453X

ABSTRACT=<p>Diffusion-weighted Imaging (DWI) is an effective and state-of-the-art neuroimaging method that non-invasively reveals the microstructure and connectivity of tissues. Recently, novel applications of the DWI technique in studying large brains through <italic>ex-vivo</italic> imaging enabled researchers to gain insights into the complex neural architecture in different species such as those of <italic>Perissodactyla</italic> (e.g., horses and rhinos), <italic>Artiodactyla</italic> (e.g., bovids, swines, and cetaceans), and <italic>Carnivora</italic> (e.g., felids, canids, and pinnipeds). Classical <italic>in-vivo</italic> tract-tracing methods are usually considered unsuitable for ethical and practical reasons, in large animals or protected species. <italic>Ex-vivo</italic> DWI-based tractography offers the chance to examine the microstructure and connectivity of formalin-fixed tissues with scan times and precision that is not feasible <italic>in-vivo</italic>. This paper explores DWI’s application to <italic>ex-vivo</italic> brains of large animals, highlighting the unique insights it offers into the structure of sometimes phylogenetically different neural networks, the connectivity of white matter tracts, and comparative evolutionary adaptations. Here, we also summarize the challenges, concerns, and perspectives of <italic>ex-vivo</italic> DWI that will shape the future of the field in large brains.</p>