Spatial navigation is a fundamental ability for animals living in a geometric space. While animals use various strategies to reach a desired location, many lines of evidence suggest that rats are able to use geometric relationships of landmarks, or a map, for navigation. Supporting this idea, neurons that fire selectively depending on the animal’s position, such as place cells or grid cells, were discovered in the hippocampus and accompanying parahippocampal structures. However, while these cells may be ideal to estimate the animal’s instantaneous position, it has been largely unclear how these cells are used to plan a next movement to reach the goal location.
In our research group, we investigate the neural circuits that are required for animals to implement map-based navigation. Specifically, we are interested in how the spatial representation in the hippocampus is used in downstream brain structures for route planning. To achieve this aim, we perform high-density chronic recordings from freely behaving rats to monitor hundreds of neurons simultaneously across multiple brain areas involved in navigation. Due to the data complexity, our analyses largely rely on statistical and computational methods to decipher the neural code. The recording experiments are supplemented with optogenetic and pharmacogenetic manipulations of the neural activity to understand the computational impact of a particular subset of neurons in the circuits.
Our research focus is not limited to cortical regions. The hippocampus has long been considered to have extensive anatomical interactions with subcortical structures in the thalamus and hypothalamus. We investigate the functional contribution of these subcortical areas, particularly in long-range communication across multiple brain structures including the hippocampus.