Characterization of Behaviors During Food Consumption Under Novelty and Threat Learning in Male and Female Rats (MK Thesis)

It remains unclear whether behavioral responses to novelty can impact subsequent threat learning and memory. The current study first examined food consumption of a novel versus familiar food in either a novel or familiar context, across two tests. During the first test, rats in a familiar context consumed more of the familiar food than those in a novel context, while novel food consumption did not differ by context. During the second test, consumption of both foods did not differ by context. Females ate more of the novel than the familiar food and ate more novel food than males. All subjects increased their consumption from the first to the second test. These findings indicate partial reduction of neophobia with prior exposure to the testing context, and sex differences in processing novelty. Subjects next underwent a threat learning paradigm involving acquisition, extinction, and renewal of a cued tone-foot shock association.Twelve behaviors were observed, categorized as immobility-based defensive behaviors (freezing), movement-based defensive (mobility) behaviors, and non-defensive (neutral) behaviors. During acquisition, all subjects increased freezing but not mobility behaviors in response to the tone, demonstrating successful acquisition of immobility-based fear. During extinction, all subjects decreased freezing behavior and increased mobility and neutral behaviors, indicating extinction learning. Females exhibited more mobility behaviors than males during extinction, suggesting sex difference in extinguished fear memory expression. During renewal testing, all subjects showed increased freezing in the acquisition context compared to the extinction context, both at baseline and during the tone, indicating renewal of immobility-based fear. Renewal of mobility behaviors was not observed, indicating that mobility behaviors were not conditioned to the tone. There were no significant differences in freezing, mobility, or neutral behaviors based on prior novelty exposure, but these findings establish a behavioral baseline for examining how novelty-related experience may interact with threat learning and memory and reveal meaningful sex differences across both paradigms.