The Role of Hippocampal and Thalamic Inputs to Retrosplenial Cortex in Spatial Navigation and Memory
1 Universitätsklinikum Bonn
The retrosplenial cortex (RSC) is essential for spatial navigation and memory, supported by its diverse connectivity. It houses various neurons representing spatial features, including head direction cells, egocentric boundary vector cells, and border cells, which are thought to contribute to its ability to integrate egocentric and allocentric information crucial for navigational behavior. Anatomically, the RSC has prominent connections not only to sensory areas but also to key brain regions involved in spatial cognition, including the hippocampal formation and the thalamus. Notably, layer 1 of the dorsal granular RSC (gRSC) receives convergent excitatory input from the anterior thalamus and long-range inhibitory input from the hippocampal CA1 area. Recent studies have suggested opposing actions of hippocampal and thalamic input to gRSC in memory processing. Still, the precise role of this network motive in navigation and in the encoding, consolidation, and retrieval of spatial memory is unknown. We address how hippocampal long-range inhibition of gRSC affects spatial memory using an automated spatial memory task and optogenetic interventions in mice. We have established a microprism implantation for large-scale miniature two-photon Ca2+ imaging in gRSC, allowing long-term recording from gRSC and its axonal afferents in freely moving mice. By combining a navigation task with optogenetics and miniature two-photon microscopy, we explore the information flow in the hippocampal-thalamic-retrosplenial network and aim to shed light on its role in spatial behavior and memory.