Poster: Passive Transport Disrupts Grid Cell Firing Patterns. Shawn Winter and Jeff Taube.
Both Grid Cells and Head Direction Cells are thought to be path integrators. That is, each cell type is thought to be driven as a function of the animal’s movement. For head-direction cells firing is thought to be driven by rotational movement; for grid cells a combination of rotation and translation. There are distinct sources of self-movement information: motor action plans, proprioception, and feedback from the environment. Winter and Taube sought to dissect these by removing “action plans” (and some proprioception) by comparing firing in these cell types during passive and active movement.
The apparatus was a cute vehicle, used for passive transport. Rats were recorded in a large chamber under two conditions: in the cart or during free walking.
One findings was that entorhinal cells with strong grid cell firing patterns during walking had their patterns disrupted during passive transport.
A second finding was that entorhinal head direction cells retrained head -direction firing patterns during passive transport, although peak firing rates decreased.
These findings support the notion that grid cells are path integrators. Additionally the path integrator appears to require motor-action signals.