Cognition, Behavior, and Memory
Author: Maria Sol Ramos | Email: m_sol_ramos@hotmail.com
Maria Sol Ramos1°2°, Sebastian Romano1°,Julieta Campi1°, Antonia Marin-Burgin1°, Noel Federman1°
1° IBioBA-MPSP-CONICET
2° FCEN-UBA
The dentate gyrus (DG), a key area in the hippocampus for spatial memory, contains neurons responsive to various factors like position, direction, sensory cues, reward, and speed. While these neurons are often viewed as encoding single variables, their multiplexing ability is becoming increasingly evident in different brain areas, including the DG. However, the hierarchy and learning-dependent changes of this neural code remain less understood. In our study, we trained head-fixed, water-restricted mice in a virtual reality environment to perform a discrimination task based on distinct cues. Using in-vivo electrophysiology, we compared DG responses in first session and expert animals. By applying an adapted Poisson generalized linear model (GLM), we found that neurons exhibit multiplexing responses. Particularly, the percentage of speed cells and the contribution of this variable to neural activity increased with learning. These neurons showed either linear modulation or tuning curve-like responses and could display speed-retrospective or prospective activity. Behaviorally, expert mice adjusted their velocity based on position and sensory stimuli. Moreover, using a virtual corridor moving at a constant velocity, preliminary results indicated that speed cell modulation depends on the animal’s movement rather than optic flow. These findings suggest that as mice become experts, DG neurons improve speed encoding, showing dynamic neural adaptation during learning.