Path Integration

How does the brain use internal (prioprioceptive) and external (world, sensory) cues together to form a representation of the world and find our way from point A to point B?  While many aspects of this broad question remain unresolved, there have been insights over the last few decades with the discovery of key cell types from place cells (discovered by John O'Keefe's group in 1971) to grid cells (discovered by May-Britt and Edvard Moser's groups in 2005) to a more recent discovery of my own, a cell termed a cue cell (described in two papers, one in Cell 2018 and one in ELife 2020. We propose that these cue cells are used by areas of the brain which form spatial maps to update errors that accumulate over time.  

More specifically: 

To look at grid cell activity over repeated traversals, we first characterized grid cell activity by recording from identified grid cells during foraging in real 2D environments and then recording the same grid cell's activity during navigation of a virtual environment comprised of a long hallway. Mice were trained to slow down and lick the lick tube in the region at the end of the hallway. Contact with the lick tube in the correct region resulted in a water or chocolate milk reward being administered. On some trials, the cues for the reward zone were not present and we trained animals to still lick the lick tube to report they had found the reward location. In these trials we found errors to accumulate in their estimate of distance.