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 Functional correlates of the lateral and medial entorhinal cortex: objects, path integration and local–global reference frames

2014 ◽  
Vol 369 (1635) ◽  
pp. 20130369 ◽  
Author(s):  
James J. Knierim ◽  
Joshua P. Neunuebel ◽  
Sachin S. Deshmukh
Keyword(s):  
Entorhinal Cortex ◽  
Path Integration ◽  
Sensory Input ◽  
Reference Frames ◽  
External Input ◽  
Frame Of Reference ◽  
Medial Entorhinal Cortex ◽  
Motion Cues ◽  
Cortical Input ◽  
Self Motion

The hippocampus receives its major cortical input from the medial entorhinal cortex (MEC) and the lateral entorhinal cortex (LEC). It is commonly believed that the MEC provides spatial input to the hippocampus, whereas the LEC provides non-spatial input. We review new data which suggest that this simple dichotomy between ‘where’ versus ‘what’ needs revision. We propose a refinement of this model, which is more complex than the simple spatial–non-spatial dichotomy. MEC is proposed to be involved in path integration computations based on a global frame of reference, primarily using internally generated, self-motion cues and external input about environmental boundaries and scenes; it provides the hippocampus with a coordinate system that underlies the spatial context of an experience. LEC is proposed to process information about individual items and locations based on a local frame of reference, primarily using external sensory input; it provides the hippocampus with information about the content of an experience.

scholarly journals Dynamic and reversible remapping of network representations in an unchanging environment

2020 ◽  
Author(s):  
Isabel I. C. Low ◽  
Alex H. Williams ◽  
Malcolm G. Campbell ◽  
Scott W. Linderman ◽  
Lisa M. Giocomo
Keyword(s):  
Entorhinal Cortex ◽  
Neural Coding ◽  
Environmental Changes ◽  
Sensory Information ◽  
Population Level ◽  
Spatial Coding ◽  
Medial Entorhinal Cortex ◽  
Neural Representations ◽  
Cell Firing ◽  
Firing Properties

AbstractIn response to environmental changes, the medial entorhinal cortex alters its single-cell firing properties. This flexibility in neural coding is hypothesized to support navigation and memory by dividing sensory experience into unique contextual episodes. However, it is unknown how the entorhinal circuit transitions between different representations, particularly when sensory information is not delineated into discrete contexts. Here, we describe spontaneous and abrupt transitions between multiple spatial maps of an unchanging task and environment. These remapping events were synchronized across hundreds of medial entorhinal neurons and correlated with changes in running speed. While remapping altered spatial coding in individual neurons, we show that features of the environment were statistically preserved at the population-level, enabling simple decoding strategies. These findings provoke a reconsideration of how medial entorhinal cortex dynamically represents space and broadly suggest a remarkable capacity for higher-order cortical circuits to rapidly and substantially reorganize their neural representations.

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 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 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.

Allocentric to Egocentric Spatial Switching: Impairment in aMCI and Alzheimer's Disease Patients?

2018 ◽  
Vol 15 (3) ◽  
pp. 229-236 ◽  
Author(s):  
Gennaro Ruggiero ◽  
Alessandro Iavarone ◽  
Tina Iachini
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Reference Frame ◽  
Reference Frames ◽  
Memory Task ◽  
Spatial Representations ◽  
The Novel ◽  
Spatial Memory Task ◽  
Switching Condition ◽  
Normal Controls

Objective: Deficits in egocentric (subject-to-object) and allocentric (object-to-object) spatial representations, with a mainly allocentric impairment, characterize the first stages of the Alzheimer's disease (AD). Methods: To identify early cognitive signs of AD conversion, some studies focused on amnestic-Mild Cognitive Impairment (aMCI) by reporting alterations in both reference frames, especially the allocentric ones. However, spatial environments in which we move need the cooperation of both reference frames. Such cooperating processes imply that we constantly switch from allocentric to egocentric frames and vice versa. This raises the question of whether alterations of switching abilities might also characterize an early cognitive marker of AD, potentially suitable to detect the conversion from aMCI to dementia. Here, we compared AD and aMCI patients with Normal Controls (NC) on the Ego-Allo- Switching spatial memory task. The task assessed the capacity to use switching (Ego-Allo, Allo-Ego) and non-switching (Ego-Ego, Allo-Allo) verbal judgments about relative distances between memorized stimuli. Results: The novel finding of this study is the neat impairment shown by aMCI and AD in switching from allocentric to egocentric reference frames. Interestingly, in aMCI when the first reference frame was egocentric, the allocentric deficit appeared attenuated. Conclusion: This led us to conclude that allocentric deficits are not always clinically detectable in aMCI since the impairments could be masked when the first reference frame was body-centred. Alongside, AD and aMCI also revealed allocentric deficits in the non-switching condition. These findings suggest that switching alterations would emerge from impairments in hippocampal and posteromedial areas and from concurrent dysregulations in the locus coeruleus-noradrenaline system or pre-frontal cortex.

scholarly journals Mouse entorhinal cortex encodes a diverse repertoire of self-motion signals

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Caitlin S. Mallory ◽  
Kiah Hardcastle ◽  
Malcolm G. Campbell ◽  
Alexander Attinger ◽  
Isabel I. C. Low ◽  
...  
Keyword(s):  
Entorhinal Cortex ◽  
Medial Temporal Lobe ◽  
Visual Cues ◽  
Neural Circuits ◽  
Sensory Cues ◽  
Medial Entorhinal Cortex ◽  
Representation Of Space ◽  
Self Motion ◽  
Information Streams ◽  
Representations Of Space

AbstractNeural circuits generate representations of the external world from multiple information streams. The navigation system provides an exceptional lens through which we may gain insights about how such computations are implemented. Neural circuits in the medial temporal lobe construct a map-like representation of space that supports navigation. This computation integrates multiple sensory cues, and, in addition, is thought to require cues related to the individual’s movement through the environment. Here, we identify multiple self-motion signals, related to the position and velocity of the head and eyes, encoded by neurons in a key node of the navigation circuitry of mice, the medial entorhinal cortex (MEC). The representation of these signals is highly integrated with other cues in individual neurons. Such information could be used to compute the allocentric location of landmarks from visual cues and to generate internal representations of space.

A role for medial entorhinal cortex in spatial and nonspatial forms of memory in rats

2021 ◽  
pp. 113259
Author(s):  
Jena B. Hales ◽  
Nicole T. Reitz ◽  
Jonathan L. Vincze ◽  
Amber C. Ocampo ◽  
Stefan Leutgeb ◽  
...  
Keyword(s):  
Entorhinal Cortex ◽  
Medial Entorhinal Cortex
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