scholarly journals Object and object-memory representations across the proximodistal axis of CA1

2020 ◽  
Author(s):  
Brianna Vandrey ◽  
James A. Ainge
Keyword(s):  
Episodic Memory ◽  
Entorhinal Cortex ◽  
Place Cells ◽  
Spatial Representations ◽  
Place Field ◽  
Medial Entorhinal Cortex ◽  
Object Memory ◽  
Place Memory ◽  
Object Locations ◽  
Memory Representations

AbstractEpisodic memory requires information about objects to be integrated into a spatial framework. Place cells in the hippocampus encode spatial representations of objects that could be generated through signalling from the entorhinal cortex. Projections from lateral and medial entorhinal cortex to the hippocampus terminate in distal and proximal CA1, respectively. We recorded place cells in distal and proximal CA1 as rats explored an environment that contained objects. Place cells in distal CA1 demonstrated higher measures of spatial tuning and expressed place fields closer to objects. Further, remapping to object displacement was modulated by place field proximity to objects in distal, but not proximal CA1. Finally, representations of previous object locations were more precise in distal CA1. Our data suggest that lateral entorhinal cortex inputs to the hippocampus support spatial representations that are more precise and responsive to objects in cue-rich environments. This is consistent with functional segregation in the entorhinal-hippocampal circuits underlying object-place memory.

scholarly journals Medial Entorhinal Cortex Lesions Only Partially Disrupt Hippocampal Place Cells and Hippocampus-Dependent Place Memory

Cell Reports ◽  
2014 ◽  
Vol 9 (3) ◽  
pp. 893-901 ◽  
Author(s):  
Jena B. Hales ◽  
Magdalene I. Schlesiger ◽  
Jill K. Leutgeb ◽  
Larry R. Squire ◽  
Stefan Leutgeb ◽  
...  
Keyword(s):  
Entorhinal Cortex ◽  
Place Cells ◽  
Medial Entorhinal Cortex ◽  
Place Memory

scholarly journals Place cell map genesis via competitive learning and conjunctive coding in the dentate gyrus

2019 ◽  
Author(s):  
Soyoun Kim ◽  
Dajung Jung ◽  
Sébastien Royer
Keyword(s):  
Dentate Gyrus ◽  
Spatial Information ◽  
Grid Cell ◽  
Place Cells ◽  
Competitive Learning ◽  
Spatial Representations ◽  
Object Locations ◽  
Network Pattern ◽  
Treadmill Belt ◽  
The Continuum

AbstractPlace cells exhibit spatially selective firing fields and collectively map the continuum of positions in environments; how such network pattern develops with experience remains unclear. Here, we recorded putative granule (GC) and mossy (MC) cells from the dentate gyrus (DG) over 27 days as mice repetitively ran through a sequence of objects fixed onto a treadmill belt. We observed a progressive transformation of GC spatial representations, from a sparse encoding of object locations and periodic spatial intervals to increasingly more single, evenly dispersed place fields, while MCs showed little transformation and preferentially encoded object locations. A competitive learning model of the DG reproduced GC transformations via the progressive integration of landmark-vector cells and grid cell inputs and required MC-mediated feedforward inhibition to evenly distribute GC representations, suggesting that GCs progressively encode conjunctions of objects and spatial information via competitive learning, while MCs help homogenize GC spatial representations.

scholarly journals Distal CA1 maintains a more coherent spatial representation than proximal CA1 when local and global cues conflict

2020 ◽  
Author(s):  
Sachin S. Deshmukh
Keyword(s):  
Entorhinal Cortex ◽  
Spatial Representation ◽  
Reference Frames ◽  
Sensory Information ◽  
Spatial Representations ◽  
Transverse Axis ◽  
Medial Entorhinal Cortex ◽  
Spatial Selectivity ◽  
Functional Differences ◽  
Cortical Projections

AbstractEntorhinal cortical projections show segregation along the transverse axis of CA1, with the medial entorhinal cortex (MEC) sending denser projections to proximal CA1 (pCA1) and the lateral entorhinal cortex (LEC) sending denser projections to distal CA1 (dCA1). Previous studies have reported functional segregation along the transverse axis of CA1 correlated with the functional differences in MEC and LEC. pCA1 shows higher spatial selectivity than dCA1 in these studies. We employ a double rotation paradigm, which creates an explicit conflict between local and global cues, to understand differential contributions of these reference frames to the spatial code in pCA1 and dCA1. We show that pCA1 and dCA1 respond differently to this local-global cue conflict. pCA1 shows incoherent response consistent with the strong conflicting inputs it receives from MEC and distal CA3 (dCA3). In contrast, dCA1 shows a more coherent rotation with global cues. In addition, pCA1 and dCA1 display comparable levels of spatial selectivity in this study. This finding differs from the previous studies, perhaps due to richer sensory information available in our behavior arena. Together these observations indicate that the functional segregation along proximodistal axis of CA1 is not merely of the amount of spatial selectivity but that of the nature of the different inputs utilized to create and anchor spatial representations.

scholarly journals Behavior-dependent spatial maps enable efficient theta phase coding

2021 ◽  
Author(s):  
Eloy Parra-Barrero ◽  
Kamran Diba ◽  
Sen Cheng
Keyword(s):  
Place Cells ◽  
Spatial Representations ◽  
Place Field ◽  
Phase Code ◽  
Phase Precession ◽  
Relevant Variables ◽  
Theta Phase ◽  
Hippocampal Theta ◽  
Exact Relationship ◽  
Speed Characteristic

AbstractNavigation through space involves learning and representing relationships between past, current and future locations. In mammals, this might rely on the hippocampal theta phase code, where in each cycle of the theta oscillation, spatial representations start behind the animal’s location and then sweep forward. However, the exact relationship between phase and represented and true positions remains unclear and even paradoxical. Here, we formalize previous notions as ‘spatial’ or ‘temporal’ sweeps, analyze single-cell and population variables in recordings from rat CA1 place cells, and compare them to model simulations. We show that neither sweep type quantitatively accounts for all relevant variables. Thus we introduce ‘behavior-dependent’ sweeps, which fit our key observation that sweep length, and hence place field properties, such as size and phase precession, vary across the environment depending on the running speed characteristic of each location. This structured heterogeneity is essential for understanding the hippocampal code.

scholarly journals Influence of boundary removal on the spatial representations of the medial entorhinal cortex

Hippocampus ◽  
2008 ◽  
Vol 18 (12) ◽  
pp. 1270-1282 ◽  
Author(s):  
Francesco Savelli ◽  
D. Yoganarasimha ◽  
James J. Knierim
Keyword(s):  
Entorhinal Cortex ◽  
Spatial Representations ◽  
Medial Entorhinal Cortex

scholarly journals Place cell maps slowly develop via competitive learning and conjunctive coding in the dentate gyrus

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Soyoun Kim ◽  
Dajung Jung ◽  
Sébastien Royer
Keyword(s):  
Dentate Gyrus ◽  
Spatial Information ◽  
Granule Cells ◽  
Place Cells ◽  
Competitive Learning ◽  
Spatial Representations ◽  
Mossy Cells ◽  
Object Locations ◽  
Treadmill Belt ◽  
The Continuum

Abstract Place cells exhibit spatially selective firing fields that collectively map the continuum of positions in environments; how such activity pattern develops with experience is largely unknown. Here, we record putative granule cells (GCs) and mossy cells (MCs) from the dentate gyrus (DG) over 27 days as mice repetitively run through a sequence of objects fixed onto a treadmill belt. We observe a progressive transformation of GC spatial representations, from a sparse encoding of object locations and spatial patterns to increasingly more single, evenly dispersed place fields, while MCs show little transformation and preferentially encode object locations. A competitive learning model of the DG reproduces GC transformations via the progressive integration of landmark-vector cells and spatial inputs and requires MC-mediated feedforward inhibition to evenly distribute GC representations, suggesting that GCs slowly encode conjunctions of objects and spatial information via competitive learning, while MCs help homogenize GC spatial representations.

scholarly journals Egocentric coding of external items in the lateral entorhinal cortex

Science ◽  
2018 ◽  
Vol 362 (6417) ◽  
pp. 945-949 ◽  
Author(s):  
Cheng Wang ◽  
Xiaojing Chen ◽  
Heekyung Lee ◽  
Sachin S. Deshmukh ◽  
D. Yoganarasimha ◽  
...  
Keyword(s):  
Episodic Memory ◽  
Spatial Cognition ◽  
Entorhinal Cortex ◽  
Essential Role ◽  
Reference Frames ◽  
Single Neurons ◽  
Spatial Coding ◽  
Medial Entorhinal Cortex ◽  
Neural Representations ◽  
Conscious Recollection

Episodic memory, the conscious recollection of past events, is typically experienced from a first-person (egocentric) perspective. The hippocampus plays an essential role in episodic memory and spatial cognition. Although the allocentric nature of hippocampal spatial coding is well understood, little is known about whether the hippocampus receives egocentric information about external items. We recorded in rats the activity of single neurons from the lateral entorhinal cortex (LEC) and medial entorhinal cortex (MEC), the two major inputs to the hippocampus. Many LEC neurons showed tuning for egocentric bearing of external items, whereas MEC cells tended to represent allocentric bearing. These results demonstrate a fundamental dissociation between the reference frames of LEC and MEC neural representations.

scholarly journals Hippocampal Spike-Timing Correlations Lead to Hexagonal Grid Fields

2017 ◽  
Author(s):  
Mauro M Monsalve-Mercado ◽  
Christian Leibold
Keyword(s):  
Synaptic Plasticity ◽  
Pattern Formation ◽  
Entorhinal Cortex ◽  
Turing Instability ◽  
Place Cells ◽  
Spike Timing ◽  
Mammalian Brain ◽  
Inhibition Mechanism ◽  
Temporal Code ◽  
Medial Entorhinal Cortex

Space is represented in the mammalian brain by the activity of hippocampal place cells as well as in their spike-timing correlations. Here we propose a theory how this temporal code is transformed to spatial firing rate patterns via spike-timing-dependent synaptic plasticity. The resulting dynamics of synaptic weights resembles well-known pattern formation models in which a lateral inhibition mechanism gives rise to a Turing instability. We identify parameter regimes in which hexagonal firing patterns develop as they have been found in medial entorhinal cortex.

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.

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