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Date of Award

2020

Document Type

Restricted Thesis: Campus only access

Degree Name

Bachelor of Science

Department

Psychology

First Advisor

Dr. Kelly Lambert

Abstract

The neocortex of the raccoon (procyon lotor) is uniquely organized in accordance with the raccoon’s diverse ecological niche profile and lifestyle characteristics (Krubitzer, 2007). In addition to species-specific cortical field distributions, raccoons are known for their flexible behavior and advanced problem-solving abilities (Pettit, 2010). In the current study, captive raccoons were exposed to a multi-access puzzle box to assess problem-solving ability. Animals that solved three solutions of the puzzle (n=7) were compared to raccoons that solved one or two solutions (n=6) and those who failed to solve any of the puzzle solutions (n=6). One hemisphere of each brain was prepared for isotropic fractionation, a technique used to quantify overall cell density (Herculano-Houzel & Lent, 2005) and the other was prepared for histological analysis using thionin staining. Following histological processing, cell counts in the hippocampus were quantified due to its potential contributing roles in problem-solving competency. The high problem-solving group exhibited significantly more cells in the hippocampus than the intermediate and low problem-solving group (p=0.029; x=51,472,917; x=37,131,875; x=35,237,500, respectively). Additionally von Economo-like neurons were found for the first time in the raccoon hippocampus. These neurons have been implicated in social cognition and animal intelligence (Allman et al., 2010). Together, these findings are informative considering past findings of function-driven hippocampal modifications (e.g., larger hippocampus in foodstoring birds; Krebs et al., 1989). Additional neurobiological research utilizing various animals characterized by unique neurobiological niches is necessary to provide information about functional outcomes associated with varying measures of brain structure and plasticity.

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