Cortical Morphology and White Matter Tractography of Three Phylogenetically Distant Primates: Evidence for a Simian Elaboration

Abstract

Comparative neuroimaging has been used to identify changes in white matter architecture across primate species phylogenetically close to humans, but few have compared the phylogenetically distant species. Here, we acquired postmortem diffusion imaging data from ring-tailed lemurs (Lemur catta), black-capped squirrel monkeys (Saimiri boliviensis), and rhesus macaques (Macaca mulatta). We were able to establish templates and surfaces allowing us to investigate sulcal, cortical, and white matter anatomy. The results demonstrate an expansion of the frontal projections of the superior longitudinal fasciculus complex in squirrel monkeys and rhesus macaques compared to ring-tailed lemurs, which correlates with sulcal anatomy and the lemur’s smaller prefrontal granular cortex. The connectivity of the ventral pathway in the parietal region is also comparatively reduced in ring-tailed lemurs, with the posterior projections of the inferior longitudinal fasciculus not extending toward parietal cortical areas as in the other species. In the squirrel monkeys we note a very specific occipito-parietal anatomy that is apparent in their surface anatomy and the expansion of the posterior projections of the optical radiation. Our study supports the hypothesis that the connectivity of the prefrontal-parietal regions became relatively elaborated in the simian lineage after divergence from the prosimian lineage.

The Digital Brain Bank, an open access platform for post-mortem imaging datasets

“…The Digital Brain Zoo provides access to post-mortem imaging datasets in nonhuman species covering multiple taxonomic ranks ( Figure 2a ), including nonhuman primate species ( Bryant et al, 2021 ; Roumazeilles et al, 2020 ; Roumazeilles et al, 2021 ), Carnivora ( Grewal et al, 2020 ), Marsupials ( Berns and Ashwell, 2017 ), and Cetaceans ( Berns et al, 2015 ). As with other collections in the Digital Brain Bank , the Digital Brain Zoo currently focuses primarily on whole-brain diffusion MRI.…”

“…Limited Derived Outputs from users of Digital Brain Bank datasets will also be considered for data upload. The first release to the Digital Brain Bank includes data from multiple published projects covering a breadth of neuroimaging research, including whole-brain diffusion MRI in 14 nonhuman primate species ( Bryant et al, 2021 ; Roumazeilles et al, 2020 ; Roumazeilles et al, 2021 ), and one of the largest post-mortem whole-brain cohort imaging studies combining whole-brain MRI and microscopy in human neurodegeneration ( Pallebage-Gamarallage et al, 2018 ). In addition, we present a previously unpublished project providing one of the highest-resolution whole-brain human diffusion MRI datasets ever acquired (500 μm isotropic resolution).…”

Structural and Cognitive Solutions to Prevent Group Fragmentation in Group-Living Species

“…In primates, this very large connectome, with its massive white matter connections, takes up a substantial proportion of the non-visual cortex, contributing significantly to overall brain size. Moreover, it exhibits significant enlargement in anthropoid primates compared to prosimians [89].…”

Social isolation and the brain in the pandemic era

“…Probably unique to anthropoid primates 35 , these cognitive skills involve specialized neural circuits in the brain, in particular the perspective-taking-related default network 24,[36][37][38] . A proto-form of that macroscopic brain system has been identified in other primates, where it also underpins sociality [39][40][41][42][43][44] .…”