Author response: Visual landmarks sharpen grid cell metric and confer context specificity to neurons of the medial entorhinal cortex

Neurons of the medial entorhinal cortex (MEC) provide spatial representations critical for navigation. In this network, the periodic firing fields of grid cells act as a metric element for position. The location of the grid firing fields depends on interactions between self-motion information, geometrical properties of the environment and nonmetric contextual cues. Here, we test whether visual information, including nonmetric contextual cues, also regulates the firing rate of MEC neurons. Removal of visual landmarks caused a profound impairment in grid cell periodicity. Moreover, the speed code of MEC neurons changed in darkness and the activity of border cells became less confined to environmental boundaries. Half of the MEC neurons changed their firing rate in darkness. Manipulations of nonmetric visual cues that left the boundaries of a 1D environment in place caused rate changes in grid cells. These findings reveal context specificity in the rate code of MEC neurons.

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Author response for "Complementary roles of differential medial entorhinal cortex inputs to the hippocampus for the formation and integration of temporal and contextual memory"

10.1111/ejn.14737/v4/response1 ◽

2020 ◽

Author(s):

William D. Marks ◽

Naoki Yamamoto ◽

Takashi Kitamura

Keyword(s):

Entorhinal Cortex ◽

Author Response ◽

Contextual Memory ◽

Medial Entorhinal Cortex

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Neuronal rebound spiking, resonance frequency and theta cycle skipping may contribute to grid cell firing in medial entorhinal cortex

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2012.0523 ◽

2014 ◽

Vol 369 (1635) ◽

pp. 20120523 ◽

Cited By ~ 28

Author(s):

Michael E. Hasselmo

Keyword(s):

Resonance Frequency ◽

Entorhinal Cortex ◽

Functional Role ◽

Grid Cell ◽

Medial Septum ◽

Medial Entorhinal Cortex ◽

Spatial Periodicity ◽

Cell Firing ◽

Rebound Spiking ◽

Relationship Of

Data show a relationship of cellular resonance and network oscillations in the entorhinal cortex to the spatial periodicity of grid cells. This paper presents a model that simulates the resonance and rebound spiking properties of entorhinal neurons to generate spatial periodicity dependent upon phasic input from medial septum. The model shows that a difference in spatial periodicity can result from a difference in neuronal resonance frequency that replicates data from several experiments. The model also demonstrates a functional role for the phenomenon of theta cycle skipping in the medial entorhinal cortex.

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Systemic administration of two different anxiolytic drugs decreases local field potential theta frequency in the medial entorhinal cortex without affecting grid cell firing fields

Neuroscience ◽

10.1016/j.neuroscience.2017.08.056 ◽

2017 ◽

Vol 364 ◽

pp. 60-70 ◽

Cited By ~ 8

Author(s):

Caitlin K. Monaghan ◽

G. William Chapman ◽

Michael E. Hasselmo

Keyword(s):

Entorhinal Cortex ◽

Local Field ◽

Local Field Potential ◽

Field Potential ◽

Grid Cell ◽

Systemic Administration ◽

Medial Entorhinal Cortex ◽

Theta Frequency ◽

Anxiolytic Drugs ◽

Cell Firing

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How to build a grid cell

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2012.0520 ◽

2014 ◽

Vol 369 (1635) ◽

pp. 20120520 ◽

Cited By ~ 8

Author(s):

Christoph Schmidt-Hieber ◽

Michael Häusser

Keyword(s):

Entorhinal Cortex ◽

Action Potentials ◽

Path Integration ◽

Grid Cell ◽

Medial Entorhinal Cortex ◽

Synaptic Inputs ◽

New Findings ◽

Cell Firing

Neurons in the medial entorhinal cortex fire action potentials at regular spatial intervals, creating a striking grid-like pattern of spike rates spanning the whole environment of a navigating animal. This remarkable spatial code may represent a neural map for path integration. Recent advances using patch-clamp recordings from entorhinal cortex neurons in vitro and in vivo have revealed how the microcircuitry in the medial entorhinal cortex may contribute to grid cell firing patterns, and how grid cells may transform synaptic inputs into spike output during firing field crossings. These new findings provide key insights into the ingredients necessary to build a grid cell.

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ARM-Cortex M3-Based Two-Wheel Robot for Assessing Grid Cell Model of Medial Entorhinal Cortex: Progress towards Building Robots with Biologically Inspired Navigation-Cognitive Maps

Journal of Robotics ◽

10.1155/2017/8069654 ◽

2017 ◽

Vol 2017 ◽

pp. 1-9

Author(s):

J. Cuneo ◽

L. Barboni ◽

N. Blanco ◽

M. del Castillo ◽

J. Quagliotti

Keyword(s):

Embedded System ◽

Entorhinal Cortex ◽

Cell Model ◽

Systems Design ◽

Grid Cell ◽

Network Models ◽

Time Algorithm ◽

Neural Network Models ◽

Biologically Inspired ◽

Medial Entorhinal Cortex

This article presents the implementation and use of a two-wheel autonomous robot and its effectiveness as a tool for studying the recently discovered use of grid cells as part of mammalian’s brains space-mapping circuitry (specifically the medial entorhinal cortex). A proposed discrete-time algorithm that emulates the medial entorhinal cortex is programed into the robot. The robot freely explores a limited laboratory area in the manner of a rat or mouse and reports information to a PC, thus enabling research without the use of live individuals. Position coordinate neural maps are achieved as mathematically predicted although for a reduced number of implemented neurons (i.e., 200 neurons). However, this type of computational embedded system (robot’s microcontroller) is found to be insufficient for simulating huge numbers of neurons in real time (as in the medial entorhinal cortex). It is considered that the results of this work provide an insight into achieving an enhanced embedded systems design for emulating and understanding mathematical neural network models to be used as biologically inspired navigation system for robots.

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Non-rhythmic head-direction cells in the parahippocampal region are not constrained by attractor network dynamics

eLife ◽

10.7554/elife.35949 ◽

2018 ◽

Vol 7 ◽

Cited By ~ 9

Author(s):

Olga Kornienko ◽

Patrick Latuske ◽

Mathis Bassler ◽

Laura Kohler ◽

Kevin Allen

Keyword(s):

Entorhinal Cortex ◽

Computational Models ◽

Tuning Curve ◽

Rhythmic Activity ◽

External World ◽

Head Direction ◽

Visual Landmarks ◽

Head Direction Cells ◽

Medial Entorhinal Cortex ◽

Attractor Network

Computational models postulate that head-direction (HD) cells are part of an attractor network integrating head turns. This network requires inputs from visual landmarks to anchor the HD signal to the external world. We investigated whether information about HD and visual landmarks is integrated in the medial entorhinal cortex and parasubiculum, resulting in neurons expressing a conjunctive code for HD and visual landmarks. We found that parahippocampal HD cells could be divided into two classes based on their theta-rhythmic activity: non-rhythmic and theta-rhythmic HD cells. Manipulations of the visual landmarks caused tuning curve alterations in most HD cells, with the largest visually driven changes observed in non-rhythmic HD cells. Importantly, the tuning modifications of non-rhythmic HD cells were often non-coherent across cells, refuting the notion that attractor-like dynamics control non-rhythmic HD cells. These findings reveal a new population of non-rhythmic HD cells whose malleable organization is controlled by visual landmarks.

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