Grid cells and the functional correlates of space in the adult brain
Research Project
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01.05.2019
- 31.12.2024
The medial entorhinal cortex (MEC) supports the brain's representation of space with distinct cell types whose firing is tuned to features of the environment (grid, border, and object-vector cells) or navigation (head-direction and speed cells), and whose somata are anatomically intermingled in layer 2 of the MEC (MEC-L2). Since no single sensory stimulus can faithfully predict the firing of these cells, and activity patterns are preserved across environments and brain states, attractor network models postulate that spatially-tuned firing emerges from specific connectivity motives among neurons of the MEC. To dissect the topology of such motives, we will study how activity self-organizes in conditions in which the path integrator of MEC-L2 is able to spontaneously drift along with the connectivity matrix of the network. To this end, we will use 2-photon calcium imaging to monitor the activity of large populations of MEC-L2 neurons in head-fixed mice running on a wheel in darkness, in the absence of external sensory feedback tuned to navigation. To reveal network dynamics under these conditions, we will apply both linear and non-linear dimensionality reduction techniques to the spike matrix of each individual session. Our aim is to dissect the rules governing connectivity in the entorhinal cortex and understand how the MEC-L2 network supports the production of regular and abstract firing patterns like those of grid cells.