scholarly journals Thalamocortical and Intracortical Laminar Connectivity Determines Sleep Spindle Properties

2017 ◽  
Author(s):  
Giri P Krishnan ◽  
Burke Q Rosen ◽  
Jen-Yung Chen ◽  
Lyle Muller ◽  
Terrence J Sejnowski ◽  
...  
Keyword(s):  
Memory Consolidation ◽  
Sleep Spindles ◽  
Spontaneous Generation ◽  
Matrix System ◽  
Sleep Spindle ◽  
Cortical Layers ◽  
Cortical Connectivity ◽  
Core System ◽  
The Core ◽  
The Matrix

AbstractSpindle oscillations are brief oscillatory activity during non-rapid eye movement (NREM) sleep. Spindle density and synchronization properties are different in MEG versus EEG recordings in humans and also vary with learning performance, suggesting spindle involvement in memory consolidation. Using computational models, we identified network mechanisms that may explain differences in spindle properties across cortical structures. First, we report that differences in spindle occurrence between MEG and EEG data may arise from the properties of the core vs. matrix thalamocortical systems. The matrix system, projecting superficially, has wider thalamocortical fanout compared to the core system, projecting to the middle layers, and requires the recruitment of a larger population of neurons to initiate a spindle. Our model demonstrates that this property is sufficient to explain lower spindle density and higher spatial synchrony of spindles in the superficial cortical layers, as observed in the EEG signal. In contrast, spindles in the core system occurred more frequently but less synchronously, as observed in the MEG recordings. Futhermore, consistent with human recordings, in the model, spindles occurred independently in the core system but matrix system spindles commonly co-occurred with core one. We found that the intracortical excitatory connections from layer III/IV to layer V promote spindle propagation from the core to the matrix system, leading to widespread spindle activity. Our study predicts that plasticity of the intra and inter cortical connectivity can potentially be a mechanism for increasing in spindle density as observed during learning.Author summaryThe density of sleep spindles has been shown to correlate with memory consolidation. Further, sleep spindles occur more often in human MEG than EEG. We developed thalamocortical network model that is capable of spontaneous generation of spindles across cortical layers and that captures the essential statistical features of spindles observed in experiments. We predict that differences in thalamo-cortical connectivity, known from anatomical studies, lead to the differences in the spindle properties between EEG and MEG as observed in human recordings. Further, we predict that the intracortical connectivity between cortical layers, a property influenced by sleep preceding learning, increases spindle density. Results from our study highlight the role of cortical and thalamic projections on the occurrence and properties of spindles.

Pharmacologically Increasing Sleep Spindles Enhances Recognition for Negative and High-arousal Memories

2013 ◽  
Vol 25 (10) ◽  
pp. 1597-1610 ◽  
Author(s):  
Erik J. Kaestner ◽  
John T. Wixted ◽  
Sara C. Mednick
Keyword(s):  
Rem Sleep ◽  
Memory Consolidation ◽  
Declarative Memory ◽  
Memory Performance ◽  
Emotional Memory ◽  
Limited Range ◽  
Sleep Spindles ◽  
Sleep Spindle ◽  
Emotional Stimuli ◽  
Valence And Arousal

Sleep affects declarative memory for emotional stimuli differently than it affects declarative memory for nonemotional stimuli. However, the interaction between specific sleep characteristics and emotional memory is not well understood. Recent studies on how sleep affects emotional memory have focused on rapid eye movement sleep (REM) but have not addressed non-REM sleep, particularly sleep spindles. This is despite the fact that sleep spindles are implicated in declarative memory as well as neural models of memory consolidation (e.g., hippocampal neural replay). Additionally, many studies examine a limited range of emotional stimuli and fail to disentangle differences in memory performance because of variance in valence and arousal. Here, we experimentally increase non-REM sleep features, sleep spindle density, and SWS, with pharmacological interventions using zolpidem (Ambien) and sodium oxybate (Xyrem) during daytime naps. We use a full spread of emotional stimuli to test all levels of valence and arousal. We find that increasing sleep spindle density increases memory discrimination (da) for highly arousing and negative stimuli without altering measures of bias (ca). These results indicate a broader role for sleep in the processing of emotional stimuli with differing effects based on arousal and valence, and they raise the possibility that sleep spindles causally facilitate emotional memory consolidation. These findings are discussed in terms of the known use of hypnotics in individuals with emotional mood disorders.

scholarly journals A New Method for Artificial Core Reconstruction of a Fracture-Control Matrix Unit

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Qiang Liu ◽  
Jianjun Liu ◽  
Guihong Pei ◽  
Zhengwen Zhu ◽  
Yun Lei
Keyword(s):  
Numerical Simulation ◽  
Fractured Reservoirs ◽  
Low Permeability ◽  
Fracture System ◽  
Matrix System ◽  
The Core ◽  
Matrix Unit ◽  
The Matrix ◽  
Control Matrix ◽  
Fracture Control

The fracture-control matrix unit (F-CMU) is a special body present in low-permeability fractured reservoirs that can be distinguished by a fracture system and a matrix system. The imbibition phenomenon of the F-CMU provides the possibility for secondary development of low-permeability fractured reservoirs because of the driving force including capillary force and gravity. However, the F-CMU is difficult to obtain during the field core drilling, which has limited the development for laboratory dynamic imbibition tests. Therefore, a new F-CMU reconstruction method is proposed in this study. According to the geometry and parameters, combining laser engraving technology, the fracture system is designed and engraved. Then, the F-CMU is established using a three-dimensional (3D) printed material called polyvinyl alcohol (PVA) as fracture support material which has a faster dissolution rate and causes less damage to the core due to water being the solvent. Finally, the porosity, permeability, and wettability of the matrix system and the T2 spectra from nuclear magnetic resonance (NMR) before and after reconstruction are measured. In addition, numerical simulation calculation of F-CMU permeability is performed. The results show that the characteristic parameters of the matrix system hardly change, indicating low damage to the core. The reconstructed fracture system is found on the T2 spectra, and the fracture permeability is consistent by comparing with the experimental and numerical simulation results. The permeability of the fracture system is about 104 orders of magnitude of the matrix system, which is closer to real core and meets the requirements needed for dynamic permeability experiments.

scholarly journals Of the matrics of the equilibrium of the rod formation system based on the principle the duality of the problems of structures mechanics

2019 ◽  
Vol 298 ◽  
pp. 00055
Author(s):  
Vladimir Monakhov
Keyword(s):  
Cross Sections ◽  
Incidence Matrix ◽  
Matrix Form ◽  
Duality Principle ◽  
Core System ◽  
The Core ◽  
The Matrix ◽  
Equilibrium Matrix ◽  
Nodal Displacements ◽  
Formation System

The formation of the equilibrium matrix of the core system in the matrix form is based on the use of the mechanical model of the system obtained by its discretization. The topological structure of the model is set using the graph and the accompanying incidence matrix. The matrix transformation of the vector of nodal displacements in combination with the extended incidence matrix allows determining the absolute elongations and distortions of each finite element. The composition of only two matrices (matrix of incidence and lengths of elements) and the skew vector leads to a geometric matrix characterizing the dependence of concentrated bending deformations in the calculated cross sections of the core system from the nodal displacements for a given load. Based on the duality principle, by transposing the geometric matrix, the equilibrium equation of the core system is derived in matrix form.

Dysfunctional Overnight Memory Consolidation in Patients with Schizophrenia in Comparison to Healthy Controls: Disturbed Slow-Wave Sleep as Contributing Factor?

2021 ◽  
pp. 1-12
Author(s):  
Sara Lena Weinhold ◽  
Julia Lechinger ◽  
Jasper Ittel ◽  
Romina Ritzenhoff ◽  
Henning Johannes Drews ◽  
...  
Keyword(s):  
Linear Relationship ◽  
Slow Wave ◽  
Memory Consolidation ◽  
Slow Wave Sleep ◽  
Declarative Memory ◽  
Sleep Spindles ◽  
Sleep Spindle ◽  
Delta Power ◽  
Sleep Parameters ◽  
Spindle Power

<b><i>Introduction:</i></b> Memory deficiency has been shown in schizophrenia patients, but results on the role of sleep parameters in overnight consolidation of associative verbal memory are still missing. Therefore, the aim of our study was to elucidate underlying processes of impaired sleep-related consolidation of associative word pairs in schizophrenia including standard sleep parameters as well as sleep spindle counts and spectral analysis. <b><i>Methods:</i></b> Eighteen stably medicated schizophrenia patients and 24 healthy age-matched controls performed an associative declarative memory task before and after polysomnographic recordings. Part of the participants expected verbal associative memory testing in the morning, while the others did not. Furthermore, participants filled in self-rating questionnaires of schizophrenia-typical experiences (Eppendorf Schizophrenia Inventory [ESI] and Psychotic Symptom Rating Scale). <b><i>Results:</i></b> Schizophrenia patients performed worse in verbal declarative memory in the evening as well as in overnight consolidation (morning compared to evening performance). While duration of slow-wave sleep was nearly comparable between groups, schizophrenia patients showed lower sleep spindle count, reduced delta power during slow-wave sleep, and reduced spindle power during the slow oscillation (SO) up-state. In healthy but not in schizophrenia patients, a linear relationship between overnight memory consolidation and slow-wave sleep duration as well as delta power was evident. No significant effect with respect to the expectation of memory retrieval was evident in our data. Additionally, we observed a negative linear relationship between total number of sleep spindles and ESI score in healthy participants. <b><i>Discussion/Conclusion:</i></b> As expected, schizophrenia patients showed deficient overnight verbal declarative memory consolidation as compared to healthy controls. Reduced sleep spindles, delta power, and spindle power during the SO up-state may link sleep and memory deficiency in schizophrenia. Additionally, the absence of a linear relationship between sleep-related memory consolidation and slow-wave sleep as well as delta power suggests further functional impairments in schizophrenia. Note that this conclusion is based on observational data. Future studies should investigate if stimulation of delta waves during sleep could improve memory performance and thereby quality of life in schizophrenia.

scholarly journals Sleep spindles and cognition in depression

2017 ◽  
Author(s):  
Leonore Bovy ◽  
Martin Dresler ◽  
Frederik D Weber
Keyword(s):  
Memory Consolidation ◽  
Cognitive Abilities ◽  
Declarative Memory ◽  
Critical Role ◽  
Antidepressant Medication ◽  
Sleep Spindles ◽  
Sleep Spindle ◽  
Preliminary Model ◽  
Patient Groups ◽  
Medication Selection

Sleep plays a critical role in orchestrating several cognitive functions. Sleep spindles are particularly at the forefront of studies on the consolidation of cognitive abilities, such as procedural and declarative memory. Despite that major depressive disorder (MDD) has been linked to sleep spindle alterations, their role in MDD pathogenesis and symptomatology (including memory deficits) is still scarcely investigated. Here, we first provide an overview of sleep and sleep spindle alterations in MDD and their potential effects on memory and cognition. Secondly, limited data suggest that sleep spindles deficits in severe MDD might not only lead to cognitive impairments but primarily affect memory consolidation processes during sleep. Furthermore, it seems likely that many sleep spindle related effects are masked by interacting (antidepressant) medication, selection of mixed patient groups with mild symptomatology as well as use of incomprehensive methodology in analyzing sleep. We propose a preliminary model predicting that impairments in sleep spindle related activity during sleep are mainly responsible for memory consolidation deficits in depressed patients, but that medication augmenting sleep spindle activity can enhance and restore sleep-mediated consolidation. Future studies thus need to scrutinize previous findings on sleep spindle effects in MDD.

scholarly journals Electrophysiological Indicators of Sleep-associated Memory Consolidation in 5- to 6-year-old Children

2020 ◽  
Author(s):  
Ann-Kathrin Joechner ◽  
Sarah Wehmeier ◽  
Markus Werkle-Bergner
Keyword(s):  
Young Adults ◽  
School Children ◽  
Memory Consolidation ◽  
Declarative Memory ◽  
Slow Oscillation ◽  
Sleep Spindles ◽  
Sleep Spindle ◽  
Slow Oscillations ◽  
Slow Sleep ◽  
Temporal Coupling

ABSTRACTIn young adults, memory consolidation during sleep is supported by a time-coordinated interplay of sleep spindles and slow oscillations. However, given tremendous developmental changes in sleep spindle and slow oscillation morphology, it remains elusive whether the same mechanisms as identified in young adults are comparably functional across childhood. Here, we characterise slow and fast sleep spindles and their temporal coupling to slow oscillations in 24 pre-school children. Further, we ask whether slow and fast sleep spindles and their modulation during slow oscillations are similarly associated with behavioural indicators of declarative memory consolidation as suggested from adult literature. Employing a development-sensitive, individualised approach, we reliably identify an inherent, development-specific fast sleep spindle type, though nested in the adult-like slow sleep spindle frequency range, along with a dominant slow sleep spindle type. Further, we provide evidence for the modulation of fast sleep spindles during slow oscillations, already in pre-school children. However, the temporal coordination between fast sleep spindles and slow oscillations is weaker and less precise than expected from adult research. While we do not find evidence for a critical contribution of the pattern of fast sleep spindle modulation during slow oscillations for memory consolidation, crucially, both inherent slow and fast sleep spindles separately are differentially related to sleep-associated consolidation of items of varying quality. While a higher number of slow sleep spindles is associated with stronger maintenance of medium-quality memories, more fast sleep spindles are linked to higher gain of low-quality items. Our results provide evidence for two functionally relevant inherent sleep spindle types in pre-school children despite not fully matured sleep spindle – slow oscillation coupling.

scholarly journals Heterogeneous origins of human sleep spindles in different cortical layers

2017 ◽  
Author(s):  
Donald J. Hagler ◽  
Istvan Ulbert ◽  
Lucia Wittner ◽  
Lorand Erőss ◽  
Joseph R. Madsen ◽  
...  
Keyword(s):  
Memory Consolidation ◽  
Slow Wave Sleep ◽  
Current Source ◽  
Microelectrode Arrays ◽  
Phase Relationship ◽  
Gamma Activity ◽  
Sleep Spindles ◽  
Cortical Layers ◽  
Human Sleep ◽  
Deep Source

AbstractSleep spindles are a cardinal feature in human slow wave sleep and may be important for memory consolidation. We studied the intracortical organization of spindles in humans by recording spontaneous sleep spindles from different cortical layers using linear microelectrode arrays. Two patterns of spindle generation were identified using visual inspection, and confirmed with factor analysis. Spindles were largest and most common in upper and middle channels, with limited involvement of deep channels. Many spindles were observed in only upper or only middle channels, but about half occurred in both. In spindles involving both middle and upper channels, the spindle envelope onset in middle channels led upper by ∼25-50ms on average. The phase relationship between spindle waves in upper and middle channels varied dynamically within spindle epochs, and across individuals. Current source density analysis demonstrated that upper and middle channel spindles were both generated by an excitatory supragranular current sink while an additional deep source was present for middle channel spindles only. Only middle channel spindles were accompanied by deep gamma activity. These results suggest that upper channel spindles are generated by supragranular pyramids, and middle channel by infragranular. Possibly, middle channel spindles are generated by core thalamocortical afferents, and upper channel by matrix. The concurrence of these patterns could reflect engagement of cortical circuits in the integration of more focal (core) and distributed (matrix) aspects of memory. These results demonstrate that at least two distinct intracortical systems generate human sleep spindles.Significance StatementBursts of ∼14Hz oscillations, lasting about a second, have been recognized for over 80 years as cardinal features of mammalian sleep. Recent findings suggest that they play a key role in organizing cortical activity during memory consolidation. We used linear microelectrode arrays to study their intracortical organization in humans. We found that spindles could be divided into two types. One mainly engages upper layers of the cortex, which are considered to be specialized for associative activity. The other engages both upper and middle layers, including those devoted to sensory input. The interaction of these two spindle types may help organize the interaction of sensory and associative aspects of memory consolidation.

What face familiarity feelings say about the lateralization of specific entities within the core system

2019 ◽  
Vol 42 ◽  
Author(s):  
Guido Gainotti
Keyword(s):  
Temporal Lobe ◽  
Memory System ◽  
Core System ◽  
The Core ◽  
Memory Traces ◽  
Specific Memory ◽  
Target Article ◽  
Temporal Structures ◽  
The Right

Abstract The target article carefully describes the memory system, centered on the temporal lobe that builds specific memory traces. It does not, however, mention the laterality effects that exist within this system. This commentary briefly surveys evidence showing that clear asymmetries exist within the temporal lobe structures subserving the core system and that the right temporal structures mainly underpin face familiarity feelings.

The Structure and Development of Microbodies in the Fat Body and other Tissues of an Insect (Calpodes Ethlius)

1970 ◽  
Vol 28 ◽  
pp. 148-149
Author(s):  
M. Locke ◽  
J. T. McMahon
Keyword(s):  
Electron Microscopy ◽  
Liquid Crystals ◽  
Fat Body ◽  
Competitive Inhibitor ◽  
Dense Core ◽  
Urate Oxidase ◽  
Blood Proteins ◽  
Free Base ◽  
The Core ◽  
The Matrix

The fat body of insects has always been compared functionally to the liver of vertebrates. Both synthesize and store glycogen and lipid and are concerned with the formation of blood proteins. The comparison becomes even more apt with the discovery of microbodies and the localization of urate oxidase and catalase in insect fat body.The microbodies are oval to spherical bodies about 1μ across with a depression and dense core on one side. The core is made of coiled tubules together with dense material close to the depressed membrane. The tubules may appear loose or densely packed but always intertwined like liquid crystals, never straight as in solid crystals (Fig. 1). When fat body is reacted with diaminobenzidine free base and H2O2 at pH 9.0 to determine the distribution of catalase, electron microscopy shows the enzyme in the matrix of the microbodies (Fig. 2). The reaction is abolished by 3-amino-1, 2, 4-triazole, a competitive inhibitor of catalase. The fat body is the only tissue which consistantly reacts positively for urate oxidase. The reaction product is sharply localized in granules of about the same size and distribution as the microbodies. The reaction is inhibited by 2, 6, 8-trichloropurine, a competitive inhibitor of urate oxidase.

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