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Main Authors: Xu, Dehong, Gao, Ruiqi, Zhang, Wen-Hao, Wei, Xue-Xin, Wu, Ying Nian
Format: Preprint
Published: 2024
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Online Access:https://arxiv.org/abs/2405.16865
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author Xu, Dehong
Gao, Ruiqi
Zhang, Wen-Hao
Wei, Xue-Xin
Wu, Ying Nian
author_facet Xu, Dehong
Gao, Ruiqi
Zhang, Wen-Hao
Wei, Xue-Xin
Wu, Ying Nian
contents This paper investigates the conformal isometry hypothesis as a potential explanation for the hexagonal periodic patterns in grid cell response maps. We posit that grid cell activities form a high-dimensional vector in neural space, encoding the agent's position in 2D physical space. As the agent moves, this vector rotates within a 2D manifold in the neural space, driven by a recurrent neural network. The conformal hypothesis proposes that this neural manifold is a conformal isometric embedding of 2D physical space, where local physical distance is preserved by the embedding up to a scaling factor (or unit of metric). Such distance-preserving position embedding is indispensable for path planning in navigation, especially planning local straight path segments. We conduct numerical experiments to show that this hypothesis leads to the hexagonal grid firing patterns by learning maximally distance-preserving position embedding, agnostic to the choice of the recurrent neural network. Furthermore, we present a theoretical explanation of why hexagon periodic patterns emerge by minimizing our loss function by showing that hexagon flat torus is maximally distance preserving.
format Preprint
id arxiv_https___arxiv_org_abs_2405_16865
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle On Conformal Isometry of Grid Cells: Learning Distance-Preserving Position Embedding
Xu, Dehong
Gao, Ruiqi
Zhang, Wen-Hao
Wei, Xue-Xin
Wu, Ying Nian
Neurons and Cognition
Machine Learning
This paper investigates the conformal isometry hypothesis as a potential explanation for the hexagonal periodic patterns in grid cell response maps. We posit that grid cell activities form a high-dimensional vector in neural space, encoding the agent's position in 2D physical space. As the agent moves, this vector rotates within a 2D manifold in the neural space, driven by a recurrent neural network. The conformal hypothesis proposes that this neural manifold is a conformal isometric embedding of 2D physical space, where local physical distance is preserved by the embedding up to a scaling factor (or unit of metric). Such distance-preserving position embedding is indispensable for path planning in navigation, especially planning local straight path segments. We conduct numerical experiments to show that this hypothesis leads to the hexagonal grid firing patterns by learning maximally distance-preserving position embedding, agnostic to the choice of the recurrent neural network. Furthermore, we present a theoretical explanation of why hexagon periodic patterns emerge by minimizing our loss function by showing that hexagon flat torus is maximally distance preserving.
title On Conformal Isometry of Grid Cells: Learning Distance-Preserving Position Embedding
topic Neurons and Cognition
Machine Learning
url https://arxiv.org/abs/2405.16865