title: Environmental boundaries as an error correction mechanism for grid cells.
abstract: Medial entorhinal grid cells fire in periodic, hexagonally patterned locations and are proposed to support path-integration-based navigation. The recursive nature of path integration results in accumulating error and, without a corrective mechanism, a breakdown in the calculation of location. The observed long-term stability of grid patterns necessitates that the system either performs highly precise internal path integration or implements an external landmark-based error correction mechanism. To distinguish these possibilities, we examined grid cells in behaving rodents as they made long trajectories across an open arena. We found that error accumulates relative to time and distance traveled since the animal last encountered a boundary. This error reflects coherent drift in the grid pattern. Further, interactions with boundaries yield direction-dependent error correction, suggesting that border cells serve as a neural substrate for error correction. These observations, combined with simulations of an attractor network grid cell model, demonstrate that landmarks are crucial to grid stability.
authors.affiliation: Department of Neurobiology, Stanford University, Stanford, CA 94305, USA. Electronic address: khardcas@stanford.edu.
authors.forename: Kiah
authors.initials: K
authors.lastname: Hardcastle
authors.affiliation: Department of Neurobiology, Stanford University, Stanford, CA 94305, USA; Department of Applied Physics, Stanford University, Stanford, CA 94305, USA.
authors.forename: Surya
authors.initials: S
authors.lastname: Ganguli
authors.affiliation: Department of Neurobiology, Stanford University, Stanford, CA 94305, USA. Electronic address: giocomo@stanford.edu.
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Giocomo
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D003198:Computer Simulation; D066264:Datasets as Topic; D018728:Entorhinal Cortex / Q000166:cytology*; D004777:Environment; D005106:Exploratory Behavior / Q000502:physiology; D051379:Mice; D008959:Models, Neurological; D009415:Nerve Net / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D011336:Probability; D013028:Space Perception / Q000502:physiology; D013997:Time Factors