scholarly journals Field repetition and local mapping in the hippocampus and the medial entorhinal cortex

2017 ◽  
Vol 118 (4) ◽  
pp. 2378-2388 ◽  
Author(s):  
Roddy M. Grieves ◽  
Éléonore Duvelle ◽  
Emma R. Wood ◽  
Paul A. Dudchenko
Keyword(s):  
Entorhinal Cortex ◽  
Local Area ◽  
Place Cells ◽  
Grid Cells ◽  
Medial Entorhinal Cortex ◽  
Pattern Completion ◽  
Global Space ◽  
Local Environments ◽  
Neural Substrate ◽  
The Relationship

Hippocampal place cells support spatial cognition and are thought to form the neural substrate of a global “cognitive map.” A widely held view is that parts of the hippocampus also underlie the ability to separate patterns or to provide different neural codes for distinct environments. However, a number of studies have shown that in environments composed of multiple, repeating compartments, place cells and other spatially modulated neurons show the same activity in each local area. This repetition of firing fields may reflect pattern completion and may make it difficult for animals to distinguish similar local environments. In this review we 1) highlight some of the navigation difficulties encountered by humans in repetitive environments, 2) summarize literature demonstrating that place and grid cells represent local and not global space, and 3) attempt to explain the origin of these phenomena. We argue that the repetition of firing fields can be a useful tool for understanding the relationship between grid cells in the entorhinal cortex and place cells in the hippocampus, the spatial inputs shared by these cells, and the propagation of spatially related signals through these structures.

scholarly journals Shedding light on stellate cells

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Andrew S Alexander ◽  
Michael E Hasselmo
Keyword(s):  
Entorhinal Cortex ◽  
Stellate Cells ◽  
Grid Cells ◽  
Medial Entorhinal Cortex ◽  
The Relationship

The relationship between grid cells and two types of neurons found in the medial entorhinal cortex has been clarified.

A MODEL OF GRID CELLS BASED ON A TWISTED TORUS TOPOLOGY

2007 ◽  
Vol 17 (04) ◽  
pp. 231-240 ◽  
Author(s):  
ALEXIS GUANELLA ◽  
DANIEL KIPER ◽  
PAUL VERSCHURE
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Entorhinal Cortex ◽  
Firing Frequency ◽  
Place Cells ◽  
Grid Cells ◽  
Medial Entorhinal Cortex ◽  
Triangular Grids ◽  
Multiple Regions ◽  
Robust To Noise

The grid cells of the rat medial entorhinal cortex (MEC) show an increased firing frequency when the position of the animal correlates with multiple regions of the environment that are arranged in regular triangular grids. Here, we describe an artificial neural network based on a twisted torus topology, which allows for the generation of regular triangular grids. The association of the activity of pre-defined hippocampal place cells with entorhinal grid cells allows for a highly robust-to-noise calibration mechanism, suggesting a role for the hippocampal back-projections to the entorhinal cortex.

scholarly journals A geometric attractor mechanism for self-organization of entorhinal grid modules

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Louis Kang ◽  
Vijay Balasubramanian
Keyword(s):  
Entorhinal Cortex ◽  
Network Models ◽  
Recurrent Inhibition ◽  
Modular Structure ◽  
Self Organization ◽  
Periodic Lattice ◽  
Grid Cells ◽  
Medial Entorhinal Cortex ◽  
Attractor Network ◽  
Discrete Values

Grid cells in the medial entorhinal cortex (MEC) respond when an animal occupies a periodic lattice of ‘grid fields’ in the environment. The grids are organized in modules with spatial periods, or scales, clustered around discrete values separated on average by ratios in the range 1.4–1.7. We propose a mechanism that produces this modular structure through dynamical self-organization in the MEC. In attractor network models of grid formation, the grid scale of a single module is set by the distance of recurrent inhibition between neurons. We show that the MEC forms a hierarchy of discrete modules if a smooth increase in inhibition distance along its dorso-ventral axis is accompanied by excitatory interactions along this axis. Moreover, constant scale ratios between successive modules arise through geometric relationships between triangular grids and have values that fall within the observed range. We discuss how interactions required by our model might be tested experimentally.

scholarly journals Functional connectivity of the entorhinal–hippocampal space circuit

2014 ◽  
Vol 369 (1635) ◽  
pp. 20120516 ◽  
Author(s):  
Sheng-Jia Zhang ◽  
Jing Ye ◽  
Jonathan J. Couey ◽  
Menno Witter ◽  
Edvard I. Moser ◽  
...  
Keyword(s):  
Entorhinal Cortex ◽  
Cell Types ◽  
Place Cells ◽  
Projection Neurons ◽  
Border Cells ◽  
Head Direction ◽  
Grid Cells ◽  
Head Direction Cells ◽  
Dynamic Interactions ◽  
Cell Groups

The mammalian space circuit is known to contain several functionally specialized cell types, such as place cells in the hippocampus and grid cells, head-direction cells and border cells in the medial entorhinal cortex (MEC). The interaction between the entorhinal and hippocampal spatial representations is poorly understood, however. We have developed an optogenetic strategy to identify functionally defined cell types in the MEC that project directly to the hippocampus. By expressing channelrhodopsin-2 (ChR2) selectively in the hippocampus-projecting subset of entorhinal projection neurons, we were able to use light-evoked discharge as an instrument to determine whether specific entorhinal cell groups—such as grid cells, border cells and head-direction cells—have direct hippocampal projections. Photoinduced firing was observed at fixed minimal latencies in all functional cell categories, with grid cells as the most abundant hippocampus-projecting spatial cell type. We discuss how photoexcitation experiments can be used to distinguish the subset of hippocampus-projecting entorhinal neurons from neurons that are activated indirectly through the network. The functional breadth of entorhinal input implied by this analysis opens up the potential for rich dynamic interactions between place cells in the hippocampus and different functional cell types in the entorhinal cortex (EC).

scholarly journals Spike afterpotentials shape the in-vivo burst activity of principal cells in medial entorhinal cortex

2019 ◽  
Author(s):  
Dóra É. Csordás ◽  
Caroline Fischer ◽  
Johannes Nagele ◽  
Martin Stemmler ◽  
Andreas V.M. Herz
Keyword(s):  
Entorhinal Cortex ◽  
High Frequency ◽  
Cell Group ◽  
Two Dimensional ◽  
Grid Cells ◽  
Spatial Coding ◽  
Medial Entorhinal Cortex ◽  
Whole Cell

AbstractPrincipal neurons in rodent medial entorhinal cortex (MEC) generate high-frequency bursts during natural behavior. While in vitro studies point to potential mechanisms that could support such burst sequences, it remains unclear whether these mechanisms are effective under in-vivo conditions. In this study, we focused on the membrane-potential dynamics immediately following action potentials, as measured in whole-cell recordings from male mice running in virtual corridors (Domnisoru et al., 2013). These afterpotentials consisted either of a hyperpolarization, an extended ramp-like shoulder, or a depolarization reminiscent of depolarizing afterpotentials (DAPs) recorded in vitro in MEC stellate and pyramidal neurons. Next, we correlated the afterpotentials with the cells’ propensity to fire bursts. All DAP cells with known location resided in Layer II, generated bursts, and their inter-spike intervals (ISIs) were typically between five and fifteen milliseconds. The ISI distributions of Layer-II cells without DAPs peaked sharply at around four milliseconds and varied only minimally across that group. This dichotomy in burst behavior is explained by cell-group-specific DAP dynamics. The same two groups of bursting neurons also emerged when we clustered extracellular spike-train autocorrelations measured in real two-dimensional arenas (Latuske et al., 2015). No difference in the spatial coding properties of the grid cells across all three groups was discernible. Layer III neurons were only sparsely bursting and had no DAPs. As various mechanisms for modulating the ion-channels underlying DAPs exist, our results suggest that the temporal features of MEC activity can be altered while maintaining the cells’ spatial tuning characteristics.Significance StatementDepolarizing afterpotentials (DAPs) are frequently observed in principal neurons from slice preparations of rodent medial entorhinal cortex (MEC), but their functional role in vivo is unknown. Analyzing whole-cell data from mice running on virtual tracks, we show that DAPs do occur during behavior. Cells with prominent DAPs are found in Layer II; their inter-spike intervals reflect DAP time-scales. In contrast, neither the rarely bursting cells in Layer III, nor the high-frequency bursters in Layer II, have a DAP. Extracellular recordings from mice exploring real two-dimensional arenas demonstrate that grid cells within these three groups have rather similar spatial coding properties. We conclude that DAPs shape the temporal but not the spatial response characteristics of principal neurons in MEC.Author contributionsAll authors designed research. DÉC, CF, and JN performed research and analyzed data (equal contribution). AVMH wrote and edited the paper with support from MS and the other authors.

scholarly journals A Map-like Micro-Organization of Grid Cells in the Medial Entorhinal Cortex

Cell ◽  
2018 ◽  
Vol 175 (3) ◽  
pp. 736-750.e30 ◽  
Author(s):  
Yi Gu ◽  
Sam Lewallen ◽  
Amina A. Kinkhabwala ◽  
Cristina Domnisoru ◽  
Kijung Yoon ◽  
...  
Keyword(s):  
Entorhinal Cortex ◽  
Grid Cells ◽  
Medial Entorhinal Cortex

scholarly journals Home, head direction stability, and grid cell distortion

2020 ◽  
Vol 123 (4) ◽  
pp. 1392-1406 ◽  
Author(s):  
Juan Ignacio Sanguinetti-Scheck ◽  
Michael Brecht
Keyword(s):  
Entorhinal Cortex ◽  
Home Cage ◽  
Cell Activity ◽  
Grid Cell ◽  
Head Direction ◽  
Grid Cells ◽  
Head Direction Cells ◽  
Medial Entorhinal Cortex ◽  
Abstract Approach ◽  
Globally Stable

The home is a unique location in the life of humans and animals. In rats, home presents itself as a multicompartmental space that involves integrating navigation through subspaces. Here we embedded the laboratory rat’s home cage in the arena, while recording neurons in the animal’s parasubiculum and medial entorhinal cortex, two brain areas encoding the animal’s location and head direction. We found that head direction signals were unaffected by home cage presence or translocation. Head direction cells remain globally stable and have similar properties inside and outside the embedded home. We did not observe egocentric bearing encoding of the home cage. However, grid cells were distorted in the presence of the home cage. While they did not globally remap, single firing fields were translocated toward the home. These effects appeared to be geometrical in nature rather than a home-specific distortion and were not dependent on explicit behavioral use of the home cage during a hoarding task. Our work suggests that medial entorhinal cortex and parasubiculum do not remap after embedding the home, but local changes in grid cell activity overrepresent the embedded space location and might contribute to navigation in complex environments. NEW & NOTEWORTHY Neural findings in the field of spatial navigation come mostly from an abstract approach that separates the animal from even a minimally biological context. In this article we embed the home cage of the rat in the environment to address some of the complexities of natural navigation. We find no explicit home cage representation. While both head direction cells and grid cells remain globally stable, we find that embedded spaces locally distort grid cells.

scholarly journals A theory of joint attractor dynamics in the hippocampus and the entorhinal cortex accounts for artificial remapping and grid cell field-to-field variability

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Haggai Agmon ◽  
Yoram Burak
Keyword(s):  
Entorhinal Cortex ◽  
Activity Patterns ◽  
Grid Cell ◽  
Mechanistic Explanation ◽  
Place Cells ◽  
Mammalian Brain ◽  
Dimensional Manifold ◽  
Grid Cells ◽  
Attractor Dynamics ◽  
Low Dimensional

The representation of position in the mammalian brain is distributed across multiple neural populations. Grid cell modules in the medial entorhinal cortex (MEC) express activity patterns that span a low-dimensional manifold which remains stable across different environments. In contrast, the activity patterns of hippocampal place cells span distinct low-dimensional manifolds in different environments. It is unknown how these multiple representations of position are coordinated. Here, we develop a theory of joint attractor dynamics in the hippocampus and the MEC. We show that the system exhibits a coordinated, joint representation of position across multiple environments, consistent with global remapping in place cells and grid cells. In addition, our model accounts for recent experimental observations that lack a mechanistic explanation: variability in the firing rate of single grid cells across firing fields, and artificial remapping of place cells under depolarization, but not under hyperpolarization, of layer II stellate cells of the MEC.

scholarly journals Home, head direction stability and grid cell distortion

2019 ◽  
Author(s):  
Juan Ignacio Sanguinetti-Scheck ◽  
Michael Brecht
Keyword(s):  
Entorhinal Cortex ◽  
Home Cage ◽  
Grid Cell ◽  
Neural Representation ◽  
Head Direction ◽  
Grid Cells ◽  
Medial Entorhinal Cortex ◽  
Home Location ◽  
Single Firing ◽  
Behavioral Studies

AbstractThe home is a unique location in the life of humans and animals. Numerous behavioral studies investigating homing indicate that many animals maintain an online representation of the direction of the home, a home vector. Here we placed the rat’s home cage in the arena, while recording neurons in the animal’s parasubiculum and medial entorhinal cortex. From a pellet hoarding paradigm it became evident that the home cage induced locomotion patterns characteristic of homing behaviors. We did not observe home-vector cells. We found that head-direction signals were unaffected by home location. However, grid cells were distorted in the presence of the home cage. While they did not globally remap, single firing fields were translocated towards the home. These effects appeared to be geometrical in nature rather than a home-specific distortion. Our work suggests that medial entorhinal cortex and parasubiculum do not contain an explicit neural representation of the home direction.

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