Hippocampal navigation and place recognition

The existence of place, directional, boundary and grid cells in the rat hippocampal formation provides strong evidence that it functions as a cognitive map containing map-like representations of familiar environments which enable the animal to identify its current location together with desirable and undesirable locations, and to move towards or away from these.

Using our newly developed honeycomb maze, we have shown that the CA1 place cells support flexible navigation by pointing the direction to the goal and, in addition, evaluating the suitability of all non-goalward directions as possible options if the goalward choice is not available.

We plan to explore the properties of this representation, its environmental and path integation inputs and the way in which it underpins flexible navigation. We have also shown that the CA1 place cells are sensitive to the size of the environment.

Their firing rates are modulated by a range of environmental sizes with some cells preferring small environments, others intermediate sized ones, and yet others firing only to the largest environment.

We will study exactly which aspect of environmental size and shape these cells are monitoring and how they are doing so.