title: Shearing-induced asymmetry in entorhinal grid cells.
abstract: Grid cells are neurons with periodic spatial receptive fields (grids) that tile two-dimensional space in a hexagonal pattern. To provide useful information about location, grids must be stably anchored to an external reference frame. The mechanisms underlying this anchoring process have remained elusive. Here we show in differently sized familiar square enclosures that the axes of the grids are offset from the walls by an angle that minimizes symmetry with the borders of the environment. This rotational offset is invariably accompanied by an elliptic distortion of the grid pattern. Reversing the ellipticity analytically by a shearing transformation removes the angular offset. This, together with the near-absence of rotation in novel environments, suggests that the rotation emerges through non-coaxial strain as a function of experience. The systematic relationship between rotation and distortion of the grid pattern points to shear forces arising from anchoring to specific geometric reference points as key elements of the mechanism for alignment of grid patterns to the external world.
authors: Kavli Institute for Systems Neuroscience and Centre for Neural Computation, Norwegian University of Science and Technology, Olav Kyrres gate 9, 7491 Trondheim, Norway.
authors: Tor
authors: T
authors: Stensola
authors: Kavli Institute for Systems Neuroscience and Centre for Neural Computation, Norwegian University of Science and Technology, Olav Kyrres gate 9, 7491 Trondheim, Norway.
authors: Hanne
authors: H
authors: Stensola
authors: Kavli Institute for Systems Neuroscience and Centre for Neural Computation, Norwegian University of Science and Technology, Olav Kyrres gate 9, 7491 Trondheim, Norway.
authors: May-Britt
authors: MB
authors: Moser
authors: Kavli Institute for Systems Neuroscience and Centre for Neural Computation, Norwegian University of Science and Technology, Olav Kyrres gate 9, 7491 Trondheim, Norway.
authors: Edvard I
authors: EI
authors: Moser
mesh_terms: D000200:Action Potentials; D000818:Animals; D001931:Brain Mapping; D018728:Entorhinal Cortex / Q000166:cytology* / Q000502:physiology; D004777:Environment; D008297:Male; D008959:Models, Neurological; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D009949:Orientation / Q000502:physiology*; D010364:Pattern Recognition, Visual / Q000502:physiology*; D051381:Rats; D020318:Rats, Long-Evans; D012399:Rotation; D013028:Space Perception / Q000502:physiology*; D013997:Time Factors