How does the brain’s spatial map change when we change the shape of the room?

A latest report about grid cells from Sainsbury Wellcome Centre at UCL. The following is excerpted from the report. 

Our ability to navigate the world, and form episodic memories, relies on an accurate representation of the environment around us. This cognitive map, which is thought to reside in the hippocampus of the brain, gives us the flexibility we need to find our way around in familiar places and to store the events we experience in our day-to-day lives.

Place, head-direction, boundary, and grid cells are thought to constitute the main units of this neural positioning system, the ‘GPS’ of the brain. Place cells identify the current location, head-direction cells provide compass-like information about directions, and boundary cells measure distances from landmarks such as the walls of the enclosure in which the animal finds itself. Due to their periodic firing pattern in standard symmetrical environments such as squares and circles, grid cells have traditionally been thought to represent the spatial metric system of the brain, or the coordinates of the GPS system, with place and border cells acting to stabilize the grid.

A new study, published in Science, explores the consequences of distorting the shape of the enclosing box on these cognitive maps of space. The results detail how our cognitive maps adapt to changed environments and shed light on how distinct types of neurons may connect to form these maps.

For further info, please read the paper Krupic et al., 2018.  and a report on UCL website

Krupic, Julija, Marius Bauza, Stephen Burton, and John O’Keefe. “Local transformations of the hippocampal cognitive map.” Science 359, no. 6380 (2018): 1143-1146.

Abstract: Grid cells are neurons active in multiple fields arranged in a hexagonal lattice and are thought to represent the “universal metric for space.” However, they become nonhomogeneously distorted in polarized enclosures, which challenges this view. The authors found that local changes to the configuration of the enclosure induce individual grid fields to shift in a manner inversely related to their distance from the reconfigured boundary. The grid remained primarily anchored to the unchanged stable walls and showed a nonuniform rescaling. Shifts in simultaneously recorded colocalized grid fields were strongly correlated, which suggests that the readout of the animal’s position might still be intact. Similar field shifts were also observed in place and boundary cells—albeit of greater magnitude and more pronounced closer to the reconfigured boundary—which suggests that there is no simple one-to-one relationship between these three different cell types.