Contribution of head-direction cells to path integration within grid cell networks

• Applicant: Dr. Kevin Allen
• Subject Area: Cognitive, Systems and Behavioural Neurobiology
• Term: from 2019 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 428554989

Our ability to navigate efficiently during our daily activities depends on neurons of the medial entorhinal cortex. Within this brain area, grid cells provide an internal representation of our location. When we move in space, grid cells update their location estimate to reflect our moment-to-moment position, much like our current location is updated in a GPS device as we walk. This process is called path integration and, in the case of grid cells, depends on the integration of our heading and walking speed. Current computational models of gridcells propose that heading information comes from inputs from a second type of neurons called head-direction (HD) cells. Each HD cell is active only when the head of an animal points in a specific direction, with different HD cells having different preferred directions.Despite the abundance of computational models explaining path integration by grid cells, our understanding of path integration is still incomplete for at least two reasons. First, there is no clear experimental evidence that the activity of HD cell controls thedirectional component of path integration. Second, the level of heterogeneity and complexity within the HD cell population is underestimated. For example, all models assume that HD cells form a homogeneous population, but our recent experiments indicate that this is not the case. The general aim of this research project is toinvestigate whether and how HD cells contribute to path integration. We will address the following two questions: 1) Is the angular component of path integration in grid cell network controlled by the activity of head-direction cells? 2) Does the preferred direction of all HD cells in the medial entorhinal cortex depend on inputs from HD cells in thalamic areas? We will answer these questions by performing simultaneous recordings from HD cells and grid cells, and by employing optogenetic techniques to manipulate the main thalamic HD inputs to the cortex.

• DFG Programme: Research Grants