Neuroscience in the real world: Representation of position, direction and environmental borders in the hippocampal formation of bats navigating outdoors on a remote oceanic island

Navigation is a key behavior, studied by multiple research fields. In ethology, wild animals are tracked outdoors using GPS tags as they navigate hundreds of meters or kilometers. In neuroscience, experiments are very different: laboratory animals are tracked inside small ~1×1-meter boxes, while recording the activity of navigation-related neurons – such as place cells, grid cells, head-direction cells, and border cells. However, it is unknown whether these spatial neurons, as studied in small laboratory-sized environments over 50 years, are relevant to large-scale navigation in the real world – outdoors. In this proposal we will address this major gap, by conducting the first ever neural recordings from the brain’s “navigation circuit” in animals navigating outdoors. We will implant bats with tetrode microdrives, and will release them to fly on a remote, uninhabited oceanic island. Using custom wireless neural-logger and GPS, we will study the neurobiology of navigation – for the first time – in the real world. We will explore: (1) How place cells and grid cells represent large natural habitats outdoors? (2) How these neurons encode 3D space – and in particular, altitude – in an open environment without a ceiling? (3) Are there border cells in animals navigating outdoors – e.g. border cells encoding the land/sea border, which is the “end of the world” for the bat? (4) Do head-direction cells represent a geographical compass? Specifically: do they maintain their head-direction tuning across all geographical locations on the island, and irrespective of moon movements? Preliminary experiments that we conducted on Latham Island, Tanzania, showed the feasibility of this project. We will record the same neurons outdoors and indoors, in a flight-tent on the island. This research will revolutionize the neurobiology of navigation – and it will be the first neurophysiological study, in any mammalian species and any brain region, of Neuroscience in the real world.