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Firing Fields of Dorsocaudal Medial Entorhinal Cortex as a Context-Independent Spatial Map
E. Chastain and Y. Liu
tech. report CMU-RI-TR-06-02, Robotics Institute, Carnegie Mellon University, January, 2006.

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The firing fields of the ”grid cells” found in the rat dorsocaudal medial entorhinal cortex (dMEC) present a surprising pattern of context-independent regularity. We use computational means to analyze and validate the geometric and algebraic invariant properties of the firing fields, leading to a context invariant spatial map. Our method computes the specific symmetry group implicitly associated with the spatial map, and quantifies the regularity of the firing fields to achieve a symmetry-based clustering of two different types of “grid cells.” This quantified regularity makes spatial mapping more computationally efficient and suggests a way to use the dMEC firing patterns to estimate the probabilty of the rat being located at different points in the room. Finally, general properties of context-independent population codes are suggested. Namely, context-independent population codes gain robustness by introducing uncertainty and ambiguity.

Associated centers: VASC and MRTC
Associated lab/group: Biomedical Image Analysis

Number of pages: 16

E. Chastain and Y. Liu, Firing Fields of Dorsocaudal Medial Entorhinal Cortex as a Context-Independent Spatial Map, tech. report CMU-RI-TR-06-02, Robotics Institute, Carnegie Mellon University, January, 2006.

@techreport{Chastain_2006_5290,
   author = "Erick Chastain and Yanxi Liu",
   title = "Firing Fields of Dorsocaudal Medial Entorhinal Cortex as a Context-Independent Spatial Map",
   institution = "Robotics Institute, Carnegie Mellon University",
   month = "January",
   year = "2006",
   number = "CMU-RI-TR-06-02",
   address = "Pittsburgh, PA"
}