scholarly journals Transient network synchrony of the developing medial entorhinal cortex

2017 ◽  
Author(s):  
Julia Dawitz ◽  
J.J. Johannes Hjorth ◽  
Tim Kroon ◽  
Marta Ruiperez-Alonso ◽  
Nandakumar Chandrasekhar ◽  
...  
Keyword(s):  
Entorhinal Cortex ◽  
Neuronal Networks ◽  
Gabaergic Inhibition ◽  
Medial Entorhinal Cortex ◽  
The Third ◽  
Tightly Coupled ◽  
Network Synchrony ◽  
Transient Network ◽  
Firing Properties ◽  
Hippocampal Networks

AbstractThe medial entorhinal cortex (MEC) contains a variety of specialized spatially-tuned neurons whose properties emerge during the third postnatal week onwards in rodents. How neuronal networks underlying the spatial firing patterns are formed is largely unknown but they are hypothesized to develop from topographic modules of synchronized neurons in superficial MEC. Here, we show that developing MEC neuronal networks in the second postnatal week are synchronously active in spatially-grouped modules. Network synchrony is intrinsic to MEC and desynchronized just prior to the emergence of spatially-tuned firing properties. The MEC network is modulated but not driven by the immature hippocampus and is tightly-coupled to neighboring neocortical networks. Unlike hippocampal networks, developing modules are dominated by glutamatergic excitation rather than GABAergic inhibition. Our results demonstrate that intrinsically synchronous modules exist in immature MEC: these may play a key role in establishing and organizing circuitry necessary for spatially-tuned firing properties of MEC neurons.

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 Functional properties of stellate cells in medial entorhinal cortex layer II

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
David C Rowland ◽  
Horst A Obenhaus ◽  
Emilie R Skytøen ◽  
Qiangwei Zhang ◽  
Cliff G Kentros ◽  
...  
Keyword(s):  
Entorhinal Cortex ◽  
Stellate Cell ◽  
Pyramidal Cells ◽  
Stellate Cells ◽  
Cell Types ◽  
Functional Difference ◽  
Grid Cells ◽  
Medial Entorhinal Cortex ◽  
Transgenic Mouse Line ◽  
Firing Properties

Layer II of the medial entorhinal cortex (MEC) contains two principal cell types: pyramidal cells and stellate cells. Accumulating evidence suggests that these two cell types have distinct molecular profiles, physiological properties, and connectivity. The observations hint at a fundamental functional difference between the two cell populations but conclusions have been mixed. Here, we used a tTA-based transgenic mouse line to drive expression of ArchT, an optogenetic silencer, specifically in stellate cells. We were able to optogenetically identify stellate cells and characterize their firing properties in freely moving mice. The stellate cell population included cells from a range of functional cell classes. Roughly one in four of the tagged cells were grid cells, suggesting that stellate cells contribute not only to path-integration-based representation of self-location but also have other functions. The data support observations suggesting that grid cells are not the sole determinant of place cell firing.

scholarly journals Complementary Roles of Hippocampus and Medial Entorhinal Cortex in Episodic Memory

2008 ◽  
Vol 2008 ◽  
pp. 1-8 ◽  
Author(s):  
P. A. Lipton ◽  
H. Eichenbaum
Keyword(s):  
Information Processing ◽  
Episodic Memory ◽  
Entorhinal Cortex ◽  
Spatial Information ◽  
Spatial Mapping ◽  
Hippocampal Function ◽  
Medial Entorhinal Cortex ◽  
Spatially Extended ◽  
Electrophysiological Findings ◽  
Hippocampal Networks

Spatial mapping and navigation are figured prominently in the extant literature that describes hippocampal function. The medial entorhinal cortex is likewise attracting increasing interest, insofar as evidence accumulates that this area also contributes to spatial information processing. Here, we discuss recent electrophysiological findings that offer an alternate view of hippocampal and medial entorhinal function. These findings suggest complementary contributions of the hippocampus and medial entorhinal cortex in support of episodic memory, wherein hippocampal networks encode sequences of events that compose temporally and spatially extended episodes, whereas medial entorhinal networks disambiguate overlapping episodes by binding sequential events into distinct memories.

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

scholarly journals P2-071: IMPAIRED IN VIVO GAMMA OSCILLATIONS IN THE MEDIAL ENTORHINAL CORTEX OF KNOCK-IN ALZHEIMER MODEL

2019 ◽  
Vol 15 ◽  
pp. P598-P598
Author(s):  
Heechul Jun ◽  
Shogo Soma ◽  
Ananya Dasgupta ◽  
Kei Igarashi
Keyword(s):  
Entorhinal Cortex ◽  
Gamma Oscillations ◽  
Medial Entorhinal Cortex

scholarly journals The Caudal Medial Entorhinal Cortex: a Selective Role in Recollection-Based Recognition Memory

2010 ◽  
Vol 30 (46) ◽  
pp. 15695-15699 ◽  
Author(s):  
M. M. Sauvage ◽  
Z. Beer ◽  
M. Ekovich ◽  
L. Ho ◽  
H. Eichenbaum
Keyword(s):  
Recognition Memory ◽  
Entorhinal Cortex ◽  
Medial Entorhinal Cortex

Ionic mechanisms for the subthreshold oscillations and differential electroresponsiveness of medial entorhinal cortex layer II neurons

1993 ◽  
Vol 70 (1) ◽  
pp. 144-157 ◽  
Author(s):  
R. Klink ◽  
A. Alonso
Keyword(s):  
Membrane Potential ◽  
Entorhinal Cortex ◽  
Inward Rectification ◽  
Voltage Level ◽  
Medial Entorhinal Cortex ◽  
Potential Oscillations ◽  
Subthreshold Oscillations ◽  
Outward Rectification ◽  
Ionic Mechanisms ◽  
Membrane Potential Oscillations

1. Layer II of the medial entorhinal cortex is composed of two electrophysiologically and morphologically distinct types of projection neurons: stellate cells (SCs), which are distinguished by rhythmic subthreshold oscillatory activity, and non-SCs. The ionic mechanisms underlying their differential electroresponsiveness, particularly in the subthreshold range of membrane potentials, were investigated in an "in vitro" slice preparation. 2. In both SCs and non-SCs, the apparent membrane input resistance was markedly voltage dependent, respectively decreasing or increasing at hyperpolarized or subthreshold depolarized potential levels. Thus the neurons displayed inward rectification in the hyperpolarizing and depolarizing range. 3. In the depolarizing range, inward rectification was blocked by tetrodotoxin (TTX, 1 microM) in both types of neurons and thus shown to depend on the presence of a persistent low-threshold Na+ conductance (gNap). However, in the presence of TTX, pronounced outward rectification became manifest in the subthreshold depolarizing range of membrane potentials (positive to -60 mV) in the SCs but not in the non-SCs. 4. The rhythmic subthreshold membrane potential oscillations that were present only in the SCs were abolished by TTX and not by Ca2+ conductance block with Cd2+ or Co2+. Subthreshold oscillations thus rely on the activation of voltage-gated Na+, and not Ca2+, conductances. The Ca2+ conductance block also had no effect on the subthreshold outward rectification. 5. Prominent time-dependent inward rectification in the hyperpolarizing range in the SCs persisted after Na(+)- and Ca2+ conductance block. This rectification was not affected by Ba2+ (1 mM), but was blocked by Cs+ (1-4 mM). Therefore, it is most probably generated by a hyperpolarization-activated cationic current (Q-like current). However, the Q-like current appears to play no major role in the generation of subthreshold rhythmic membrane potential oscillations, because these persisted in the presence of Cs+. 6. On the other hand, in the SCs, the fast, sustained, outward rectification that strongly developed (after Na+ conductance block) at the oscillatory voltage level was not affected by Cs+ but was blocked by Ba2+ (1 mM). Barium was also effective in blocking the subthreshold membrane potential oscillations. 7. In the non-SCs, which do not generate subthreshold rhythmic membrane potential oscillations or manifest subthreshold outward rectification in TTX, Ca2+ conductance block abolished spike repolarization and caused the development of long-lasting Na(+)-dependent plateau potentials at a high suprathreshold voltage level. At this level, where prominent delayed rectification is present, the Na+ plateaus sustained rhythmic membrane potential oscillations.(ABSTRACT TRUNCATED AT 400 WORDS)

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