An Ongoing Subthreshold Neuronal State Established Through Dynamic Coassembling of Cortical Cells

2008 ◽  
Vol 20 (12) ◽  
pp. 3055-3086 ◽  
Author(s):  
Osamu Hoshino
Keyword(s):  
Neuronal Activity ◽  
Network Model ◽  
Sensory Stimulation ◽  
Local Network ◽  
Activity Period ◽  
Cell Assembly ◽  
Core Nucleus ◽  
Cell Assemblies ◽  
Transient Dynamic ◽  
The Core

Ensemble activation of neurons, triggered or spontaneous, sometimes involves a common (overlapping) neuronal population known as core cells. It is speculated that the core cells functioning as a core nucleus have a role in dictating noncore cells' behavior and thus overall local network dynamics. However, the truth and its significance in neuronal information processing still remain to be seen. To address this issue, a neural network model of an early sensory cortical area was simulated. In the network model, noncore cells that have selective responsiveness to sensory features constituted noncore cell assemblies. Core cells, having unselective responsiveness, constituted a single core cell assembly. Sensory stimulation activated neuronal ensembles that were indistinguishable from those activated spontaneously. The core cells were active in every ensemble activation and recruited a changing complement of noncore cells, which varied from spontaneous event to spontaneous event or from triggered event to triggered event. Ensemble activation of neurons was established through what we call dynamic coassembling, in which the core cell assembly and one of the noncore cell assemblies were dynamically linked together. Transient dynamic coassembling frequently and randomly took place during the ongoing (spontaneous) neuronal activity period, and persistent dynamic coassembling did during the stimulus-triggered neuronal activity period. The frequent ongoing activation of core cells mediated through transient dynamic coassembling depolarized noncore cells just below firing threshold, whereby the noncore cells could respond rapidly to sensory stimulation. The persistent dynamic coassembling enhanced the responsiveness of noncore cells. We suggest that the core cells, functioning as a core nucleus, dictate how the noncore cells oscillate at a subthreshold level during the ongoing period and how to respond when stimulated. The transient and persistent dynamic coassembling may be an essential neuronal mechanism for the cortex to prepare and respond effectively to sensory input.

scholarly journals Dynamic core periphery structure of information sharing networks in entorhinal cortex and hippocampus

2020 ◽  
Author(s):  
Nicola Pedreschi ◽  
Christophe Bernard ◽  
Wesley Clawson ◽  
Pascale Quilichini ◽  
Alain Barrat ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Information Sharing ◽  
Cell Assembly ◽  
Temporal Network ◽  
Cell Assemblies ◽  
The Core ◽  
Temporal Connectivity ◽  
Network States ◽  
Information Sharing Networks ◽  
Share Information

ABSTRACTNeural computation is associated with the emergence, reconfiguration and dissolution of cell assemblies in the context of varying oscillatory states. Here, we describe the complex spatio-temporal dynamics of cell assemblies through temporal network formalism. We use a sliding window approach to extract sequences of networks of information sharing among single units in hippocampus and enthorinal cortex during anesthesia and study how global and node-wise functional connectivity properties evolve along time and as a function of changing global brain state (theta vs slow-wave oscillations). First, we find that information sharing networks display, at any time, a core-periphery structure in which an integrated core of more tightly functionally interconnected units link to more loosely connected network leaves. However the units participating to the core or to the periphery substantially change across time-windows, with units entering and leaving the core in a smooth way. Second, we find that discrete network states can be defined on top of this continuously ongoing liquid core-periphery reorganization. Switching between network states results in a more abrupt modification of the units belonging to the core and is only loosely linked to transitions between global oscillatory states. Third, we characterize different styles of temporal connectivity that cells can exhibit within each state of the sharing network. While inhibitory cells tend to be central, we show that, otherwise, anatomical localization only poorly influences the patterns of temporal connectivity of the different cells. Furthermore, cells can change temporal connectivity style when the network changes state. Altogether, these findings reveal that the sharing of information mediated by the intrinsic dynamics of hippocampal and enthorinal cortex cell assemblies have a rich spatiotemporal structure, which could not have been identified by more conventional time- or state-averaged analyses of functional connectivity.AUTHOR SUMMARYIt is generally thought that computations performed by local brain circuits rely on complex neural processes, associated to the flexible waxing and waning of cell assemblies, i.e. ensemble of cells firing in tight synchrony. Although cell assembly formation is inherently and unavoidably dynamical, it is still common to find studies in which essentially “static” approaches are used to characterize this process. In the present study, we adopt instead a temporal network approach. Avoiding usual time averaging procedures, we reveal that hub neurons are not hardwired but that cells vary smoothly their degree of integration within the assembly core. Furthermore, our temporal network framework enables the definition of alternative possible styles of “hubness”. Some cells may share information with a multitude of other units but only in an intermittent manner, as “activists” in a flash mob. In contrast, some other cells may share information in a steadier manner, as resolute “lobbyists”. Finally, by avoiding averages over pre-imposed states, we show that within each global oscillatory state a rich switching dynamics can take place between a repertoire of many available network states. We thus show that the temporal network framework provides a natural and effective language to rigorously describe the rich spatiotemporal patterns of information sharing instantiated by cell assembly evolution.

Reduction of Trial-to-Trial Perceptual Variability by Intracortical Tonic Inhibition

2016 ◽  
Vol 28 (1) ◽  
pp. 187-215 ◽  
Author(s):  
Osamu Hoshino ◽  
Meihong Zheng ◽  
Kazuo Watanabe
Keyword(s):  
Neuronal Activity ◽  
Network Model ◽  
Dependent Manner ◽  
Gaba Concentration ◽  
Cell Assemblies ◽  
Principal Cells ◽  
Ambient Gaba ◽  
Spontaneous Neuronal Activity ◽  
Perceptual Variability ◽  
Feature Stimulus

Variability is a prominent characteristic of cognitive brain function. For instance, different trials of presentation of the same stimulus yield higher variability in its perception: subjects sometimes fail in perceiving the same stimulus. Perceptual variability could be attributable to ongoing-spontaneous fluctuation in neuronal activity prior to sensory stimulation. Simulating a cortical neural network model, we investigated the underlying neuronal mechanism of perceptual variability in relation to variability in ongoing-spontaneous neuronal activity. In the network model, populations of principal cells (cell assemblies) encode information about sensory features. Each cell assembly is sensitive to one particular feature stimulus. Transporters on GABAergic interneurons regulate ambient GABA concentration in a neuronal activity-dependent manner. Ambient GABA molecules activate extrasynaptic GABA[Formula: see text] receptors on principal cells and interneurons, and provide them with tonic inhibitory currents. We controlled the variability of ongoing-spontaneous neuronal activity by manipulating the basal level of ambient GABA and assessed the perceptual performance of the network: detection of a feature stimulus. In an erroneous response, stimulus-irrelevant but not stimulus-relevant principal cells were activated, generating trains of action potentials. Perceptual variability, reflected in error rate in detecting the same stimulus that was presented repeatedly to the network, was increased as the variability in ongoing-spontaneous membrane potential among cell assemblies increased. Frequent, transient membrane depolarization below firing threshold was the major cause of the increased neuronal variability, for which a decrease in basal ambient GABA concentration was responsible. We suggest that ambient GABA in the brain may have a role in reducing the variability in ongoing-spontaneous neuronal activity, leading to a decrease in perceptual variability and therefore to reliable sensory perception.

scholarly journals Sublinear domination and core–periphery networks

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Marios Papachristou
Keyword(s):  
Network Model ◽  
Power Law ◽  
Real World ◽  
Random Network ◽  
Small World ◽  
The Core ◽  
Entire Network

AbstractIn this paper we devise a generative random network model with core–periphery properties whose core nodes act as sublinear dominators, that is, if the network has n nodes, the core has size o(n) and dominates the entire network. We show that instances generated by this model exhibit power law degree distributions, and incorporates small-world phenomena. We also fit our model in a variety of real-world networks.

Re-assembling the brain: Are cell assemblies the brain's language for recovery of function?

1999 ◽  
Vol 22 (2) ◽  
pp. 284-284 ◽  
Author(s):  
Chris Code
Keyword(s):  
Cognitive Functions ◽  
Recovery Of Function ◽  
Cell Assembly ◽  
Connectionist Models ◽  
Cell Assemblies ◽  
The Brain

Holistically ignited Hebbian models are fundamentally different from the serially organized connectionist implementations of language. This may be important for the recovery of language after injury, because connectionist models have provided useful insights into recovery of some cognitive functions. I ask whether cell assembly modelling can make an important contribution and whether the apparent incompatibility with successful connectionist modelling is a problem.

Unifying cell assembly theory with observations of brain dynamics

1999 ◽  
Vol 22 (2) ◽  
pp. 297-298
Author(s):  
R. Miller
Keyword(s):  
Empirical Evidence ◽  
High Frequency ◽  
Theoretical Work ◽  
Brain Dynamics ◽  
Cell Assembly ◽  
Neural Basis ◽  
Cell Assemblies ◽  
Active Representation ◽  
Sentence Planning

Empirical evidence suggests that high frequency electrographic activity is involved in active representation of meaningful entities in the cortex. Theoretical work suggests that distributed cell assemblies also represent meaningful entities. However, we are still some way from understanding how these two are related. This commentary also makes suggestions for further investigation of the neural basis of language at the level of both words and sentence planning.

Encoding Network States by Striatal Cell Assemblies

2008 ◽  
Vol 99 (3) ◽  
pp. 1435-1450 ◽  
Author(s):  
Luis Carrillo-Reid ◽  
Fatuel Tecuapetla ◽  
Dagoberto Tapia ◽  
Arturo Hernández-Cruz ◽  
Elvira Galarraga ◽  
...  
Keyword(s):  
Network Dynamics ◽  
Procedural Memory ◽  
Pattern Generation ◽  
Spatiotemporal Pattern ◽  
Cell Assembly ◽  
Striatal Neurons ◽  
Cell Assemblies ◽  
Correlated Activity ◽  
Dominant State ◽  
Network States

Correlated activity in cortico-basal ganglia circuits plays a key role in the encoding of movement, associative learning and procedural memory. How correlated activity is assembled by striatal microcircuits is not understood. Calcium imaging of striatal neuronal populations, with single-cell resolution, reveals sporadic and asynchronous activity under control conditions. However, N-methyl-d-aspartate (NMDA) application induces bistability and correlated activity in striatal neurons. Widespread neurons within the field of observation present burst firing. Sets of neurons exhibit episodes of recurrent and synchronized bursting. Dimensionality reduction of network dynamics reveals functional states defined by cell assemblies that alternate their activity and display spatiotemporal pattern generation. Recurrent synchronous activity travels from one cell assembly to the other often returning to the original assembly; suggesting a robust structure. An initial search into the factors that sustain correlated activity of neuronal assemblies showed a critical dependence on both intrinsic and synaptic mechanisms: blockage of fast glutamatergic transmission annihilates all correlated firing, whereas blockage of GABAergic transmission locked the network into a single dominant state that eliminates assembly diversity. Reduction of L-type Ca2+-current restrains synchronization. Each cell assembly comprised different cells, but a small set of neurons was shared by different assemblies. A great proportion of the shared neurons was local interneurons with pacemaking properties. The network dynamics set into action by NMDA in the striatal network may reveal important properties of striatal microcircuits under normal and pathological conditions.

scholarly journals CRY1-CBS binding regulates circadian clock function and metabolism

2020 ◽  
Author(s):  
Sibel Cal-Kayitmazbatir ◽  
Eylem Kulkoyluoglu-Cotul ◽  
Jacqueline Growe ◽  
Christopher P. Selby ◽  
Seth D. Rhoades ◽  
...  
Keyword(s):  
Carbon Metabolism ◽  
Activity Period ◽  
Metabolomic Analysis ◽  
Wild Type ◽  
Common Cause ◽  
The Core ◽  
E Box ◽  
One Carbon Metabolism ◽  
Circadian Physiology ◽  
Repressor Activity

AbstractCircadian disruption influences metabolic health. Metabolism modulates circadian function. However, the mechanisms coupling circadian rhythms and metabolism remain poorly understood. Here we report that Cystathionine β-synthase (CBS), a central enzyme in one-carbon metabolism, functionally interacts with the core circadian protein Cryptochrome1 (CRY1). In cells, CBS augments CRY1 mediated repression of the CLOCK/BMAL1 complex and shortens circadian period. Notably, we find that mutant CBS-I278T protein, the most common cause of homocystinuria, does not bind CRY1 or regulate its repressor activity. Transgenic CbsZn/Zn mice, while maintaining circadian locomotor activity period, exhibit reduced circadian power and increased expression of E-BOX outputs. CBS function is reciprocally influenced by CRY1 binding. CRY1 modulates enzymatic activity of the CBS. Liver extracts from Cry1−/− mice show reduced CBS activity that normalizes after the addition of exogenous wild type (WT) CRY1. Metabolomic analysis of WT, CbsZn/Zn, Cry1−/−, and Cry2−/− samples highlights the metabolic importance of endogenous CRY1. We observed temporal variation in one-carbon and transsulfuration pathways attributable to CRY1 induced CBS activation. CBS-CRY1 binding provides a post-translational switch to modulate cellular circadian physiology and metabolic control.

Association and computation with cell assemblies

1995 ◽  
Vol 18 (4) ◽  
pp. 643-644
Author(s):  
Frank der van Velde
Keyword(s):  
Cognitive Psychology ◽  
Classical Conditioning ◽  
Cognitive Processing ◽  
Cognitive Abilities ◽  
Cell Assembly ◽  
Cell Assemblies ◽  
Important Concept

AbstractThe cell assembly is an important concept for cognitive psychology. Cognitive processing will to a large extent depend on the relations that can exist between different assemblies. A potential relation between assemblies can already be seen in the occurrence of (classical) conditioning. However, the resulting associations between assemblies only produce behavioristic processing or so-called regular computation. Higher-level cognitive abilities most likely result from nonregular computation. I discuss the possibility of this form of computation in terms of cell assemblies.

PERBANDINGAN PENGGUNAAN KALSIUM KARBONAT DAN NATRIUM KARBONAT DALAM PEMISAHAN CANGKANG DAN KERNEL

2013 ◽  
Vol 2 (1) ◽  
pp. 29-34
Author(s):  
Vonny Indah Sari
Keyword(s):  
Specific Gravity ◽  
Sodium Carbonate ◽  
Fluid Motion ◽  
Core Nucleus ◽  
The Core

Clay bath is where the separation of the shell, core nucleus intact and broken. The process of separation occurs because of differences in density between the core with the shell with the help of a solution of CaCO3. Core with a lighter density in the solution of CaCO3 floats and shells with a greater specific gravity settle to the bottom. This process is carried out in a cone-shaped vessel is equipped with a pump to circulate CaCO3. The existence of the circulation of fluid motion will bring the kernel into the sieve vibration to be cleaned and then sent to the kernel in the Kernel Wet Fan heading to Kernel Shiloh to the heat. This reseach compared the performance of the solution with a solution of Na2CO3 and CaCO3 in their shells and kernels, seen from the solubility rate between kalsim carbonate and sodium carbonate in water

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