Effects of Tooth Loss on Naked Mole‐Rat Spatial Learning and Memory

Dental health is inextricably linked to physical and mental health. Detriments to dental health such as tooth loss result in wide‐ranging deficits, including impairments to learning and memory. The goal of this study was to examine whether tooth loss impacts the ability to navigate mazes in an animal model with both behaviorally critical incisors and a high reliance on spatial navigation in day‐to‐day activities: the naked mole‐rat. A subterranean rodent, the naked mole‐rat relies on spatial memory skills to navigate their extensive underground burrows, a feature maintained in our lab's vivarium housing. These animals provide a unique behavioral model that is arguably more comparable to human spatial navigation abilities than other rodent models due to their natural habitat and commensurate adaptations. Using a modified version of a Hebb‐Williams maze, a common paradigm for testing spatial learning and memory in rodents, adult naked mole‐rats began training one week after either sham surgeries or extraction of their lower right incisor, for five trials a day for three consecutive days. Tests of spatial memory were performed the day after the final training day, plus one week and one month later to ascertain the impact of tooth loss on spatial memory retention. The hypotheses were that tooth loss would result in: 1) a greater number of errors, 2) longer latencies to the reward chamber, 3) a greater ratio of time spent in error zones compared to correct zones, and 4) overall lowered performance on memory tests over time as seen by greater error and latencies with each successive memory test compared to sham animals. Overall, the goals of this study were to elucidate how spatial awareness related to dentition contributes to learning and memory, and inform the development of future therapeutics aimed at rectifying the deficits caused by tooth loss.