INTERACTION WITH OBJECTS TUNES BEHAVIORAL PREFERENCES AND SELECTIVITY OF HIPPOCAMPAL NEURONS IN MICE

The hippocampus encodes memory representations shaped by environmental cues, but how prolonged exposure to a familiar object affects neural activity across different contexts remains unclear. We investigated how prior experience with a familiar object influences behavior and hippocampal activity in novel contexts. We recorded calcium activity in CA1 hippocampal neurons of mice as they interacted with a target object in four distinct contexts. One group of mice was exposed to the target object for two weeks, while the control group had no prior exposure. Each context differed in geometry, presence of alternative objects, and the type of interaction with the target object. Over the first three days, mice were exposed to different contexts each day, then returned to the first context after one week. A final exposure in a fourth context included the target object with food. Behavioral analysis revealed that the mice with prior exposure approached the target object more often to sniff or sit on it compared to controls. At the neural level, we found a significantly higher number of neurons selective for sitting on the target object in the prior exposure group. Additionally, these mice had more neurons selective for the target object than for alternative objects, indicating a stable neural representation of the target object. These findings suggest that prolonged object exposure enhances the number and stability of CA1 neurons selective for the target object. Future analysis will explore the context-dependency of this encoding. Supported by the Non-commercial Foundation for Support of Science and Education “INTELLECT”.