Over the past five decades, electrophysiological research, performed mostly in rodents, has unveiled a number of cell types in the hippocampal formation and related structures that code for different aspects of spatial behavior (Hartley et al. 2013). These cell types provide us with a unique window into the neural mechanisms underlying higher level cognitive functions. Head direction cells, place cells and grid cells are among the best studied spatially modulated cell types. Head direction cells provide animals with a sense of direction by responding to the orientation of the animal’s head in space. Place cells add positional information by becoming active when the animal is located within certain circumscribed regions of the environment known as the cell’s place fields. Similarly, grid cells display multiple fields in the environment, falling on the vertices of a lattice of equilateral triangles, and seem to provide the animal with a metric representation of space. Interestingly, as animals cross a place or grid cell’s place field, the cell becomes active at progressively earlier phases of the background theta oscillation, a phenomenon known as phase precession. In a population of such phase precessing cells, within each cycle of the oscillation, the first cells to fire are ones with place fields centered behind the current position of the animal, followed by cells with place fields centered progressively more ahead. Thus, within each cycle of the oscillation we observe ‘theta sequences’ that represent, in a temporally compressed manner, a piece of the trajectory of the animal starting behind its current position and extending ahead of it.
We offer bachelor and master level theses investigating how phase precessing place cells and grid cells support spatial behavior, including functions such as learning, path integration, prediction of future positions or movement planning. Both computational modeling and data analysis projects are usually available. Some programming experience is required.
Hartley, T., C. Lever, N. Burgess, and J. O’Keefe. 2013. “Space in the Brain: How the Hippocampal Formation Supports Spatial Cognition.” Philosophical Transactions of the Royal Society B: Biological Sciences 369 (1635): 20120510–20120510. https://doi.org/10.1098/rstb.2012.0510.