GETTING TO THE ROOT OF WHETHER TOOTH EXTRACTION INFLUENCES NEUROANATOMY AND BEHAVIOR: A STUDY OF NAKED MOLE-RAT BEHAVIOR AND THE AFFECTIVE ASPECTS OF DENTITION

Author

Natalee Jordan Marcena von Keyserling, Southern Illinois University CarbondaleFollow

Date of Award

5-1-2024

Degree Name

Doctor of Philosophy

Department

Molecular, Cellular, and Systemic Physiology

First Advisor

Sarko, Diana

Abstract

Having an appropriate understanding of the behavioral and physiological impact of a disease requires thoroughly fielded tests and wide-ranging animal models to properly deduce generalized impacts of the disease under investigation. Through novel animal models, we acquire diverse insights into the mechanisms at play so that we may approach the problem at hand with fresh perspective and renewed vigor. Using the naked mole-rat (Heterocephalus glaber), a species becoming increasingly common in the medical sciences, my dissertation aimed to accomplish the aforementioned goals in two parts: 1) take the naked mole-rat through a battery of behavioral tasks to bolster our capabilities of using this animal model in medical research; and 2) introduce the naked mole-rat as an alternative model for the investigation of how loss of dental sensation alters behavior and neuroanatomy. Chapter two describes the many methods with which I tested the naked mole-rat across a variety of typical behavioral tasks for social dominance, learning and memory, anxiety, depression, and sociability. Included herein were tests to determine appropriate motivators for this subterranean species to perform such tasks. Additionally, due to the naked mole-rat’s unique disposition for biting, I measured their biting behaviors and compared them across rodent and other mammalian species. The results show that naked mole-rats exhibit large evolutionary divergence in their sensory capabilities and great consideration needs to be given to the proper behavioral tasks and subsequent evaluations of these behavioral paradigms. In chapter three, I evaluated the impact of tooth extraction on affective behaviors, learning and memory, and sociability. Chapter four sought to uncover underlying neuroplasticity associated with the behavioral tasks performed in chapter three. Additionally, in chapter four, I investigated plasticity of the traditional somatosensory pathway for tooth sensation. Tooth loss decreased neuronal density of contralateral ventral posteromedial nucleus of the thalamus and increased the neuronal density of the contralateral ventral dentate gyrus, indicating that tooth-loss induced neuronal plasticity may be more related to plasticity of pain circuitry or resultant from alterations in the muscles of mastication following tooth loss. Though no significant changes in the hippocampus arose from one year of living with no right incisor, I theorized as to which of the physiological idiosyncrasies exhibited by Heterocephalus glaber may have inhibited any observable plasticity due to tooth loss.