Cytoarchitectural characteristics associated with cognitive flexibility in raccoons

Authors

Joanna Jacob, University of Richmond
Molly Kent, Virginia Military Institute
Sarah Benson-Amram, The University of British Columbia
Suzana Herculano-Houzel, Vanderbilt University
Mary Ann Raghanti, Kent State University
Emily Ploppert, University of Richmond
Jack Drake, University of Richmond
Bilal Hindi, University of Richmond
Nick R. Natale, University of Richmond
Sarah Daniels, University of Wyoming
Rachel Fanelli, University of Wyoming
Anderson Miller, Vanderbilt University
Tim Landis, Randolph-Macon College
Amy Gilbert, USDA APHIS National Wildlife Research Center
Shylo Johnson, USDA APHIS National Wildlife Research Center
Annie Lai, University of Richmond
Molly Hyer, Randolph-Macon College
Amanda Rzucidlo, Forest Preserve District of Cook County
Chris Anchor, Forest Preserve District of Cook County
Stan Gehrt, The Ohio State University
Kelly Lambert, University of RichmondFollow

ORCID IDs

Suzana Herculano-Houzel https://orcid.org/0000-0002-1765-3599

Kelly Lambert https://orcid.org/0000-0003-1626-5129

Date of this Version

10-1-2021

Citation

J Comp Neurol. 2021;529:3375–3388.

DOI: 10.1002/cne.25197

Comments

U.S. government work

Abstract

With rates of psychiatric illnesses such as depression continuing to rise, additional preclinical models are needed to facilitate translational neuroscience research. In the current study, the raccoon (Procyon lotor) was investigated due to its similarities with primate brains, including comparable proportional neuronal densities, cortical magnification of the forepaw area, and cortical gyrification. Specifically, we report on the cytoarchitectural characteristics of raccoons profiled as high, intermediate, or low solvers in a multiaccess problem-solving task. Isotropic fractionation indicated that high-solvers had significantly more cells in the hippocampus (HC) than the other solving groups; further, a nonsignificant trend suggested that this increase in cell profile density was due to increased nonneuronal (e.g., glial) cells. Group differences were not observed in the cellular density of the somatosensory cortex. Thionin-based staining confirmed the presence of von Economo neurons (VENs) in the frontoinsular cortex, although no impact of solving ability on VEN cell profile density levels was observed. Elongated fusiform cells were quantified in the HC dentate gyrus where high-solvers were observed to have higher levels of this cell type than the other solving groups. In sum, the current findings suggest that varying cytoarchitectural phenotypes contribute to cognitive flexibility. Additional research is necessary to determine the translational value of cytoarchitectural distribution patterns on adaptive behavioral outcomes associated with cognitive performance and mental health.