What is the metric structure of the cognitive map? (360G-Wellcome-083540_Z_07_Z)

The study of how hippocampal place cells and entorhinal grid cells represent place largely underpins the cognitive neuroscience of navigation and memory. Previous studies, however, used unrealistic environments in the form of small, two-dimensional enclosures, whereas the real world has an extended, complex, three-dimensional (3-d) structure that complicates navigational processes like path integration. This project will study encoding of 3-d space by manipulating both suface elevation (using sl oped environments including a ramp and a helix) and movement through 3-d, volumetric space, to explore the questions of (1) whether planar place fields and grids are calibrated according to the environment's surface or to the horizontal plane, and (2) of whether in three dimensions, place fields are actually globular and grids are actually lattices in 3-d space. Some of these experiments will exploit newly emerging telemetric technology, which enables recording in spaces too complex for a teth ered animal to explore. The main hypothesis is that the vertical dimension is indeed encoded, but differently from the horizontal ones. The results will not only expand our understanding of the place representation but also shed light on human 3-d navigation processes in aviation, astronautics and undersea exploration, as well as design of artificial navigating agents.