Rewiring of GABAergic inhibitory cells recruited during spatial representation

• Applicants: Dr. Matthias Haberl; Dr. Silvia Viana da Silva, Ph.D.
• Subject Area: Cognitive, Systems and Behavioural Neurobiology
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 509099330

When an animal explores its surroundings, it encodes a spatial representation of the environment by activity patterns of neurons in neuronal circuits of the hippocampus. Encoding of new information in an enriched environment causes substantial re-wiring of GABAergic inhibitory neuronal circuits, characterized by an overall increase of inhibition arriving to the soma of excitatory pyramidal cells. However, it is unknown which structural and functional changes of the inhibitory network are produced by spatial encoding. We propose that re-wiring of the inhibitory network is a critical feature supporting the maintenance of cell assemblies and the stabilization of the spatial code in the hippocampus. We aim to address these fundamental questions about the spatial representation in the inhibitory network by perturbing in vivo the encoding of a spatial task and performing functional and structural analysis of the inhibitory network. We will analyse synaptic architecture using volumetric light- and electron microscopy and characterize the presynaptic profile, i.e., the number, type, strength and location of synapses onto specific cell types. In particular, we will focus on the somatic inhibition onto hippocampal pyramidal cells and the synaptic inputs onto parvalbumin (PV) interneurons, which became activated during a spatial encoding phase (engram cells). Thus, our major goal is to characterize the structural and functional changes that occur in the inhibitory network during spatial encoding. This project will contribute to improve our understanding of spatial memory by examining the role of re-organization of inhibitory circuits for the encoding of space (location) and environment.

• DFG Programme: Research Grants