Document Type
STEM
Date
2024
Submission Date
May 2024
Abstract
Norepinephrine (NE) and dopamine (DA) signaling in the hippocampus are important for normal learning and memory. Genetically-encoded fluorescent indicators of catecholamine binding allow for imaging real-time neurotransmitter dynamics. Previous microdialysis studies have found an increase in hippocampal catecholamines in response to novel environmental exposure or exercise. Since animals move in response to contextual novelty, it is unknown whether the changes in transmitter release are due to novelty or other changes in behavior or arousal. Outside of the hippocampus, arousal, novelty detection, reward, and sleep state are all related to catecholamine signaling. In this study, we use the fluorescent indicators GRAB-DA and GRAB-NE to investigate how catecholamine signaling in the hippocampus relates to novelty and movement. These variables were de-confounded by presenting novel stimuli when mice are normally at rest, thus triggering the onset of exploratory movement. Mice were also presented with novel stimuli while moving across a track, thus causing mice to stop and inspect. When mice initiated exploratory movement, we found a strong increase in DA/NE with initial object presentation that decreased over time. If the response is related to novelty, we expect to see a similar catecholamine increase in our experiments in which mice stop to explore. We further predict that these novelty responses will decrease as objects become familiar. Finally, we observed increases in DA/NE binding during the transition from sleep to waking, highlighting the need for these behavioral controls. We conclude that novelty, movement, and arousal from sleep all contribute to hippocampal catecholamine signaling.
Rights
© The Author(s)
Is Part Of
Auctus
DOI
https://doi.org/10.25886/xn6n-7q52