Online Lecture by Jori van Wijngarden

Neural Circuits for Egocentric Representation of Environmental Boundaries

The brain forms dedicated neural representations of environmental boundaries, but it remains largely unclear how these are generated and used in other brain regions. In this talk I will discuss a new type of neuron that we identified and characterized in rat retrosplenial cortex (RSC) that increase their firing near boundaries of space. These border cells specifically encode walls, but no objects, and are sensitive to the animal’s direction relative to nearby borders. We found that such egocentric representations are generated independent of visual or whisker sendsation, but instead require allocentric spatial inputs directly from the medial entorhinal cortex (MEC). Pharmaco- and optogenetic inhibition of cells in MEC led to a disruption of border coding in RSC, but not vice versa, indicating directionality in the flow of information. These data together reveal the MEC-RSC pathway as an extended border coding circuit that can implement coordinate transformation to guide navigation behaviour.