From the Research
Place cells and grid cells serve different but complementary functions in the brain's spatial navigation system, with place cells handling the "where am I?" question and grid cells managing the "how far and in what direction?" aspects of navigation. The most recent and highest quality study on this topic is from 2017, which found that the interaction between grid and place cells converges quickly, and that the spatial code of place cells does not require, but is altered by, grid cell input 1. This study suggests that the hippocampus-entorhinal circuit uses the mutual interaction of place and grid cells to encode the surrounding environment.
Some key differences between place cells and grid cells include:
- Place cells, primarily found in the hippocampus, fire when an animal is in a specific location within an environment, essentially creating a cognitive map where each cell represents a particular place.
- Grid cells, located mainly in the entorhinal cortex, fire in a regular, hexagonal pattern across the entire environment regardless of specific landmarks, providing a coordinate system or metric for measuring distances and directions.
- While place cells respond to specific environmental contexts and can remap between different environments, grid cells maintain their hexagonal firing patterns across environments, providing a consistent spatial framework.
Other studies have also explored the functions of place cells and grid cells, including a 2008 study that reviewed how place cells and grid cells may form the basis for quantitative spatiotemporal representation of places, routes, and associated experiences during behavior and in memory 2, and a 2015 study that proposed that grid cells provide a coordinate system for producing mind-travel in the hippocampus 3. However, the 2017 study provides the most recent and comprehensive understanding of the interaction between place cells and grid cells.
In terms of the implications of this research, it is clear that place cells and grid cells play critical roles in spatial navigation and memory, and that understanding their functions and interactions can provide valuable insights into the neural mechanisms underlying these processes. For example, a 2021 study explored the use of virtual reality to improve embodied representations of space and spatial memory in aging and neurodegenerative diseases, highlighting the potential for innovative rehabilitative solutions in these areas 4. Overall, the research suggests that place cells and grid cells are essential components of the brain's spatial navigation system, and that their interaction is critical for our ability to navigate and remember our surroundings.