Mapping of the entorhinal-hippocampal neuronal network
Neuroscientists have been exploring the representation of space in the brain for decades, discovering a wide range of cell types representing different navigational features. The two most prominent of these cell types were identified in the hippocampus and the medial entorhinal cortex: Place-modulated hippocampal neurons were found to be active only when an animal moves through a particular location in space (“place cells”). In the medial entorhinal cortex, cells were reported that respond in a periodic activity pattern as an animal moves through the environment (“grid cells”). Both cortical regions were found to be highly interconnected, making it plausible to expect interactions between place and grid cells. Despite extensive anatomical and functional experiments, the circuitry between grid and place cells, and how they shape each other’s activity, and the contribution of local and long-range inhibitory circuits, is still unresolved.
Our goal is to resolve the networks underlying spatial navigation tasks, in particular the interplay of neurons in the hippocampus and medial entorhinal cortex in mammals, at the single cell and single synapse level (i.e. the precise mapping of all point-to-point connections between all involved neurons at their chemical synapses). We use cutting-edge 3D electron microscopy methods for large-scale high-resolution mapping of neuronal circuits.
More Information on Helene Schmidt’s personal homepage
Schmidt H, Gour A, Straehle J, Boergens KM, Brecht M, Helmstaedter M (2017). Axonal synapse sorting in medial entorhinal cortex. Nature 549, 469–475. https://doi.org/10.1038/nature24005
Ray S, Naumann R, Burgalossi A, Tang Q, Schmidt H*, Brecht M (2014). Grid-layout and theta-modulation of layer 2 pyramidal neurons in medial entorhinal cortex. Science 343(6173), 891-896. https://doi.org/10.1126/science.1243028