INTEGRATING PATHS: BIDIRECTIONAL SEPTAL GABAERGIC MODULATION SHAPES HIPPOCAMPAL POPULATION DYNAMICS

Path integration relies on internally generated neural dynamics that allow animals to track position using self-motion cues, independent of external sensory landmarks. The medial septum (MS) is a central timing hub for hippocampal activity, yet its role in coordinating hippocampal population dynamics relevant for path integration remains poorly understood.
In this project, we investigate how GABAergic neurons in the MS influence hippocampal population activity using large-scale Neuropixels 2.0 recordings. Neuronal activity is simultaneously recorded from hippocampus, cortex, and thalamus in freely moving rodents during quiet wakefulness in the home cage, providing a controlled baseline to characterize large-scale population dynamics and inter-regional synchrony in the absence of explicit task demands. These recordings are paired with bidirectional optogenetic excitation and inhibition of MS GABAergic neurons, enabling causal manipulation of septal output while monitoring distributed population activity. Preliminary results demonstrate stable multi-region recordings and prominent synchronous population activity across cortex and thalamus, alongside structured hippocampal population dynamics.
Ongoing analyses examine how hippocampal activity aligns with global network synchrony and how optogenetically induced increases or decreases in septal GABAergic output reshape these dynamics.