scholarly journals Grid cells encode local head direction

2019 ◽  
Author(s):  
Klara Gerlei ◽  
Jessica Passlack ◽  
Ian Hawes ◽  
Brianna Vandrey ◽  
Holly Stevens ◽  
...  
Keyword(s):  
Head Direction ◽  
Grid Cells ◽  
Firing Rates ◽  
Grid Codes ◽  
Points Of View ◽  
Interference Models

Grid and head direction codes represent cognitive spaces for navigation and memory. Pure grid cells generate grid codes that have been assumed to be independent of head direction, whereas conjunctive cells generate grid representations that are tuned to a single head direction. Here, we demonstrate that pure grid cells also encode head direction, but through distinct mechanisms. We show that individual firing fields of pure grid cells are tuned to multiple head directions, with the preferred sets of directions differing between fields. This local directionality is not predicted by previous continuous attractor or oscillatory interference models of grid firing but is accounted for by models in which pure grid cells integrate inputs from co-aligned conjunctive cells with firing rates that differ between their fields. Local directional signals from grid cells may contribute to downstream computations by decorrelating different points of view from the same location.

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 Local microcircuitry of parasubiculum shows distinct and common features of excitatory and inhibitory connectivity

2020 ◽  
Author(s):  
Rosanna P Sammons ◽  
Alexandra Tzilivaki ◽  
Dietmar Schmitz
Keyword(s):  
Random Network ◽  
Spatial Navigation ◽  
Border Cells ◽  
Head Direction ◽  
Grid Cells ◽  
Medial Entorhinal Cortex ◽  
Common Features ◽  
Layer 2 ◽  
Firing Properties ◽  
Local Circuitry

The parasubiculum is located within the parahippocampal region, where it is thought to be involved in the processing of spatial navigational information. It contains a number of functionally specialised neuron types including grid cells, head direction cells and border cells, and provides input into layer 2 of the medial entorhinal cortex where grid cells are abundantly located. The local circuitry within the parasubiculum remains so far undefined but may provide clues as to the emergence of spatially tuned firing properties of neurons in this region. We used simultaneous patch-clamp recordings to determine the connectivity rates between the three major groups of neurons found in the parasubiculum. We find high rates of interconnectivity between the pyramidal class and interneurons, as well as features of pyramid to pyramid interactions indicative of a non-random network. The microcircuit that we uncover shares both similarities and divergences to those from other parahippocampal regions also involved in spatial navigation.

scholarly journals An uncertainty principle for neural coding: Conjugate representations of position and velocity are mapped onto firing rates and co-firing rates of neural spike trains

2019 ◽  
Author(s):  
Ryan Grgurich ◽  
Hugh T. Blair
Keyword(s):  
Firing Rate ◽  
Uncertainty Principle ◽  
Neural Coding ◽  
Spike Trains ◽  
Grid Cells ◽  
Rate Code ◽  
Biologically Inspired ◽  
Firing Rates ◽  
Neural Populations ◽  
Similar Information

AbstractThe hippocampal system contains neural populations that encode an animal’s position and velocity as it navigates through space. Here, we show that such populations can embed two codes within their spike trains: a firing rate code (R) conveyed by within-cell spike intervals, and a co-firing rate code (Ṙ) conveyed by between-cell spike intervals. These two codes behave as conjugates of one another, obeying an analog of the uncertainty principle from physics: information conveyed in R comes at the expense of information in Ṙ, and vice versa. An exception to this trade-off occurs when spike trains encode a pair of conjugate variables, such as position and velocity, which do not compete for capacity across R and Ṙ. To illustrate this, we describe two biologically inspired methods for decoding R and Ṙ, referred to as sigma and sigma-chi decoding, respectively. Simulations of head direction (HD) and grid cells show that if firing rates are tuned for position (but not velocity), then position is recovered by sigma decoding, whereas velocity is recovered by sigma-chi decoding. Conversely, simulations of oscillatory interference among theta-modulated “speed cells” show that if co-firing rates are tuned for position (but not velocity), then position is recovered by sigma-chi decoding, whereas velocity is recovered by sigma decoding. Between these two extremes, information about both variables can be distributed across both channels, and partially recovered by both decoders. These results suggest that neurons with different spatial and temporal tuning properties—such as speed versus grid cells—might not encode different information, but rather, distribute similar information about position and velocity in different ways across R and Ṙ. Such conjugate coding of position and velocity may influence how hippocampal populations are interconnected to form functional circuits, and how biological neurons integrate their inputs to decode information from firing rates and spike correlations.

Bio-Inspired Robotics: A Spatial Cognition Model integrating Place Cells, Grid Cells and Head Direction Cells

2018 ◽  
Vol 91 (1) ◽  
pp. 85-99 ◽  
Author(s):  
Gonzalo Tejera ◽  
Martin Llofriu ◽  
Alejandra Barrera ◽  
Alfredo Weitzenfeld
Keyword(s):  
Spatial Cognition ◽  
Place Cells ◽  
Head Direction ◽  
Grid Cells ◽  
Head Direction Cells ◽  
Cognition Model

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 Self-motion improves head direction cell tuning

2014 ◽  
Vol 111 (12) ◽  
pp. 2479-2492 ◽  
Author(s):  
Michael E. Shinder ◽  
Jeffrey S. Taube
Keyword(s):  
Firing Rate ◽  
Signal Integrity ◽  
Head Direction ◽  
Firing Rates ◽  
Cell Responses ◽  
Passive Rotation ◽  
Current State ◽  
Initial Effect ◽  
Animal Faces ◽  
Self Motion

Head direction (HD) cells respond when an animal faces a particular direction in the environment and form the basis for the animal's perceived directional heading. When an animal moves through its environment, accurate updating of the HD signal is required to reflect the current heading, but the cells still maintain a representation of HD even when the animal is motionless. This finding suggests that the HD system holds its current state in the absence of input, a view that we tested by rotating a head-restrained rat in the presence of a prominent visual landmark and then stopping it suddenly when facing the cell's preferred firing direction (PFD). Firing rates were unchanged for the first 100 ms, but then progressively decreased over the next 4 s and stabilized at ∼42% of their initial values. When the rat was stopped facing away from the PFD, there was no initial effect of braking, but the firing rate then increased steadily over 4 s and plateaued at ∼14% of its peak firing rate, substantially above initial background firing rates. In experiment 2, the rat was serially placed facing one of eight equidistant directions over 360° and held there for 30 s. Compared with the cell's peak firing rate during a passive rotation session, firing rates were reduced (51%) for in-PFD directions and increased (∼300%) from background levels for off-PFD directions, values comparable to those observed in the braking protocol. These differential HD cell responses demonstrate the importance of self-motion to the HD signal integrity.

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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