Interactions of Excitatory and Inhibitory Feedback Topologies in Facilitating Pattern Separation and Retrieval

2012 ◽  
Vol 24 (1) ◽  
pp. 32-59
Author(s):  
Jane X. Wang ◽  
Michal Zochowski
Keyword(s):  
Memory Management ◽  
Activity Patterns ◽  
Pattern Separation ◽  
Memory Recall ◽  
Cognitive States ◽  
Management Processes ◽  
Inhibitory Feedback ◽  
Global And Local ◽  
The Brain

Within the brain, the interplay between connectivity patterns of neurons and their spatiotemporal dynamics is believed to be intricately linked to the bases of behavior, such as the process of storing, consolidating, and retrieving memory traces. Memory is believed to be stored in the synaptic patterns of anatomical circuitry in the form of increased connectivity densities within subpopulations of neurons. At the same time, memory recall is thought to correspond to activation of discrete areas of the brain corresponding to those memories. Such regional subpopulations can selectively activate during memory recall or retrieval, signifying the process of accessing a single memory or concept. It has been shown previously that recovery of single memory activity patterns is mediated by global neuromodulation signifying transition into different cognitive states such as sleep or awake exploration. We examine how underlying topology can affect memory awake activation and sleep reactivation when such memories share increasing proportions of neurons. The results show that while single memory activation is diminished with increased overlap, pattern separation can be recovered by offsetting excitatory associations between two memories with targeted and heterogeneous inhibitory feedback. Such findings point to the importance of excitatory-to-inhibitory current balance at both the global and local levels in the context of memory retrieval and replay, and highlight the role of network topology in memory management processes.

scholarly journals The role of piriform associative connections in odor categorization

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Xiaojun Bao ◽  
Louise LG Raguet ◽  
Sydni M Cole ◽  
James D Howard ◽  
Jay A Gottfried
Keyword(s):  
Activity Patterns ◽  
Piriform Cortex ◽  
Discrimination Performance ◽  
Object Identification ◽  
Pattern Separation ◽  
Odor Perception ◽  
Drug Induced ◽  
Multivariate Pattern ◽  
The Brain

Distributed neural activity patterns are widely proposed to underlie object identification and categorization in the brain. In the olfactory domain, pattern-based representations of odor objects are encoded in piriform cortex. This region receives both afferent and associative inputs, though their relative contributions to odor perception are poorly understood. Here, we combined a placebo-controlled pharmacological fMRI paradigm with multivariate pattern analyses to test the role of associative connections in sustaining olfactory categorical representations. Administration of baclofen, a GABA(B) agonist known to attenuate piriform associative inputs, interfered with within-category pattern separation in piriform cortex, and the magnitude of this drug-induced change predicted perceptual alterations in fine-odor discrimination performance. Comparatively, baclofen reduced pattern separation between odor categories in orbitofrontal cortex, and impeded within-category generalization in hippocampus. Our findings suggest that odor categorization is a dynamic process concurrently engaging stimulus discrimination and generalization at different stages of olfactory information processing, and highlight the importance of associative networks in maintaining categorical boundaries.

scholarly journals Investigating the role of dendrites in pattern separation: A computational approach

2015 ◽  
Author(s):  
Spyridon Chavlis ◽  
Panagiotis C. Petrantonakis ◽  
Panayiota Poirazi
Keyword(s):  
Granule Cells ◽  
Separation Efficiency ◽  
Hamming Distance ◽  
Morphological Characteristics ◽  
Pattern Separation ◽  
Biologically Relevant ◽  
Preliminary Results ◽  
Neuronal Types ◽  
The Brain

Objectives: In order to distinguish similar memories, it is experimentally confirmed that the hippocampus forms distinct representations of them. The ability of the brain to disambiguate memories is known as pattern separation. It has been proposed that dentate gyrus (DG) accomplishes this task, specifically through its principal cells, called granule cells (GCs). In this project we investigate the role of GC dendrites in pattern separation by modifying their biophysical and morphological characteristics. Methods & Results: We have implemented a morphologically simple, yet biologically relevant, computational model of the DG that implements pattern separation. The network consists of four well-studied neuronal types: granule, mossy, basket, and HIPP cells. The GC model consists of an integrate-and-fire somatic compartment connected to a variable numbers of active dendritic compartments. For simplicity reasons, without sacrificing detail, we used point neurons to simulate the remaining neuronal types. GCs major input from the Entorhinal Cortex (EC) is simulated as independent poisson spike trains at realistic firing frequencies. The output of the network corresponds to the spiking activity of GCs and is estimated on two highly overlapping input patterns. Pattern separation is accomplished when the similarity between these input patterns is greater than the similarity between the respective output patterns, as assessed by the Hamming Distance (HD) metric. Preliminary results show that there is a positive correlation between the separation efficiency and the number of GC dendrites. Conclusions: Our preliminary results suggest that dendrites of GC cells facilitate the pattern separation capabilities of the DG.

GENESIS OF SCIENTIFIC CONCEPTS ABOUT PUBLIC ADMINISTRATION OF RISKS IN CONSTRUCTION

2018 ◽  
Vol 1 (11) ◽  
pp. 83-90
Author(s):  
Ihor Nikolayevich Vlasenko
Keyword(s):  
Risk Management ◽  
Public Administration ◽  
Design Decisions ◽  
Complex Needs ◽  
Economic Relations ◽  
Management Processes ◽  
Social And Economic Development ◽  
Public Risk ◽  
Global And Local

he article presents the characteristic of the scientific genesis of public risk management in construction in Ukraine, in global and local dimen- sions. The essence of the working organization of risk management in the con- struction and operation of buildings, taking into account the transformational processes in society, is disclosed. On the basis of the analysis of risks in construc- tion and taking into account the current realities, scientifically grounded ap- proaches to the formation of the risk system in the construction and operation of facilities in the system of public administration. It is noted that the risks and crisis phenomena in the construction complex gave a powerful impetus to un- derstanding the causes of the problems of decentralization and finding mecha- nisms for their elimination, in general. The trilateral mission of the state in the conditions of decentralization is the regulation of the macroeconomic role of the construction complex, the mechanism of economic relations of its participants, and ensuring the effectiveness of design decisions in the construction sector, by extending their competences on prevention and risk reduction in the construction industry by the local self-government bodies. To form a state decentraliza- tion policy for construction is required on the basis of knowledge of objective regional macro- and microeconomic investment-construction processes in ci- ties, economic mechanism and indicators of development of investment-build- ing complex and dynamics of social and economic development of regions. The mechanism of the construction complex needs to be improved, using new sources and forms of financing, achieving the balance of the goals of decentralization and its financial support. In addition, taking into account the European integration course of the announced reforms, the European understanding of the essence of risk management in construction during decentralization becomes of paramount importance. Therefore, further research requires the study of the experience of European countries in the implementation of risk management processes in con- struction during the decentralization of power and the analysis of foreign systems of management mechanisms, in the context of their implementation in the na- tional practice of public administration.

scholarly journals Adult hippocampal neurogenesis shapes adaptation and improves stress response: a mechanistic and integrative perspective

2021 ◽  
Author(s):  
A. Surget ◽  
C. Belzung
Keyword(s):  
Stress Response ◽  
Hippocampal Neurogenesis ◽  
Adult Hippocampal Neurogenesis ◽  
Pattern Separation ◽  
Brain Areas ◽  
Functional Involvement ◽  
Different Dimensions ◽  
Stressful Experiences ◽  
The Brain

AbstractAdult hippocampal neurogenesis (AHN) represents a remarkable form of neuroplasticity that has increasingly been linked to the stress response in recent years. However, the hippocampus does not itself support the expression of the different dimensions of the stress response. Moreover, the main hippocampal functions are essentially preserved under AHN depletion and adult-born immature neurons (abGNs) have no extrahippocampal projections, which questions the mechanisms by which abGNs influence functions supported by brain areas far from the hippocampus. Within this framework, we propose that through its computational influences AHN is pivotal in shaping adaption to environmental demands, underlying its role in stress response. The hippocampus with its high input convergence and output divergence represents a computational hub, ideally positioned in the brain (1) to detect cues and contexts linked to past, current and predicted stressful experiences, and (2) to supervise the expression of the stress response at the cognitive, affective, behavioral, and physiological levels. AHN appears to bias hippocampal computations toward enhanced conjunctive encoding and pattern separation, promoting contextual discrimination and cognitive flexibility, reducing proactive interference and generalization of stressful experiences to safe contexts. These effects result in gating downstream brain areas with more accurate and contextualized information, enabling the different dimensions of the stress response to be more appropriately set with specific contexts. Here, we first provide an integrative perspective of the functional involvement of AHN in the hippocampus and a phenomenological overview of the stress response. We then examine the mechanistic underpinning of the role of AHN in the stress response and describe its potential implications in the different dimensions accompanying this response.

scholarly journals Role of Endogenous Cannabinoids in Synaptic Signaling

2003 ◽  
Vol 83 (3) ◽  
pp. 1017-1066 ◽  
Author(s):  
TAMÁS F. FREUND ◽  
ISTVÁN KATONA ◽  
DANIELE PIOMELLI
Keyword(s):  
Neurotransmitter Release ◽  
Cannabinoid Receptor ◽  
Activity Patterns ◽  
Physiological Effect ◽  
Network Activity ◽  
Signal Molecules ◽  
Synaptic Signaling ◽  
Endogenous Cannabinoids ◽  
The Brain

Freund, Tamás F., István Katona, and Daniele Piomelli. Role of Endogenous Cannabinoids in Synaptic Signaling. Physiol Rev 83: 1017–1066, 2003; 10.1152/physrev.00004.2003.—Research of cannabinoid actions was boosted in the 1990s by remarkable discoveries including identification of endogenous compounds with cannabimimetic activity (endocannabinoids) and the cloning of their molecular targets, the CB1 and CB2 receptors. Although the existence of an endogenous cannabinoid signaling system has been established for a decade, its physiological roles have just begun to unfold. In addition, the behavioral effects of exogenous cannabinoids such as delta-9-tetrahydrocannabinol, the major active compound of hashish and marijuana, await explanation at the cellular and network levels. Recent physiological, pharmacological, and high-resolution anatomical studies provided evidence that the major physiological effect of cannabinoids is the regulation of neurotransmitter release via activation of presynaptic CB1 receptors located on distinct types of axon terminals throughout the brain. Subsequent discoveries shed light on the functional consequences of this localization by demonstrating the involvement of endocannabinoids in retrograde signaling at GABAergic and glutamatergic synapses. In this review, we aim to synthesize recent progress in our understanding of the physiological roles of endocannabinoids in the brain. First, the synthetic pathways of endocannabinoids are discussed, along with the putative mechanisms of their release, uptake, and degradation. The fine-grain anatomical distribution of the neuronal cannabinoid receptor CB1 is described in most brain areas, emphasizing its general presynaptic localization and role in controlling neurotransmitter release. Finally, the possible functions of endocannabinoids as retrograde synaptic signal molecules are discussed in relation to synaptic plasticity and network activity patterns.

scholarly journals Cholinergic neuromodulation of inhibitory interneurons facilitates functional integration in whole-brain models

2021 ◽  
Vol 17 (2) ◽  
pp. e1008737
Author(s):  
Carlos Coronel-Oliveros ◽  
Rodrigo Cofré ◽  
Patricio Orio
Keyword(s):  
Computational Models ◽  
Functional Organization ◽  
Brain Activity ◽  
Functional Integration ◽  
Whole Brain ◽  
Inhibitory Circuits ◽  
Inhibitory Feedback ◽  
Biophysical Mechanism ◽  
The Brain

Segregation and integration are two fundamental principles of brain structural and functional organization. Neuroimaging studies have shown that the brain transits between different functionally segregated and integrated states, and neuromodulatory systems have been proposed as key to facilitate these transitions. Although whole-brain computational models have reproduced this neuromodulatory effect, the role of local inhibitory circuits and their cholinergic modulation has not been studied. In this article, we consider a Jansen & Rit whole-brain model in a network interconnected using a human connectome, and study the influence of the cholinergic and noradrenergic neuromodulatory systems on the segregation/integration balance. In our model, we introduce a local inhibitory feedback as a plausible biophysical mechanism that enables the integration of whole-brain activity, and that interacts with the other neuromodulatory influences to facilitate the transition between different functional segregation/integration regimes in the brain.

Aromatherapy in the Treatment of Sexual Dysfunction and Relationship Problems (DRAFT)

2018 ◽  
Author(s):  
Mindy Green
Keyword(s):  
Sexual Dysfunction ◽  
Essential Oils ◽  
Stress Reduction ◽  
The Body ◽  
Memory Recall ◽  
Relationship Problems ◽  
Sexual Stimulation ◽  
The Brain ◽  
Dermal Application

Aromatherapy and its tools, essential oils, can be useful adjuncts to any other type of treatment for sexual dysfunction and relationship problems. Functional fragrance naturally derived from pure plant distillation (essential oils) can affect the emotions, mood, and anxiety and be an adjunct in treating behavior disorders. This chapter briefly examines the role of olfaction—the process of smelling that occurs in the same area of the brain (the limbic system) that processes memory and emotion. Essential oils are employed through inhalation or dermal application. The wide-ranging array of aromatic constituents found in essential oils can have a diverse effect on neurochemicals that are released into the body, resulting in a variety of actions: stress reduction, relaxation, mental or sexual stimulation, memory recall, and engendering intimacy.

scholarly journals The Continuity of Context: A Role for the Hippocampus

2020 ◽  
Author(s):  
Andrew Maurer ◽  
Lynn Nadel
Keyword(s):  
Stimulus Equivalence ◽  
Multiple Scales ◽  
Critical Role ◽  
Longitudinal Axis ◽  
Place Cells ◽  
Pattern Separation ◽  
Anatomy And Physiology ◽  
The Brain ◽  
Over Time

Tracking moment-to-moment change in input, and detecting change sufficient to require altering behavior is crucial to survival. We discuss how the brain evaluates change over time, focusing on hippocampus and its role in tracking context. We leverage the anatomy and physiology of the hippocampal longitudinal axis, re-entrant loops, and amorphous networks, to account for stimulus equivalence and the updating of an organism’s sense of its context. Place cells play a central role in tracking contextual continuities and discontinuities across multiple scales, a capacity beyond current models of pattern separation and completion. This perspective highlights the critical role of the hippocampus in both spatial cognition and episodic memory: tracking change and detecting boundaries separating one context, or episode, from another.

The Role of Mitochondria in the Genesis of Neuroaxonal Dystrophy in the Brains of Aging Mice

1975 ◽  
Vol 33 ◽  
pp. 372-373
Author(s):  
J.E. Johnson
Keyword(s):  
Electron Microscopy ◽  
Present Report ◽  
Light And Electron Microscopy ◽  
Dorsal Column ◽  
Neuroaxonal Dystrophy ◽  
Nucleus Gracilis ◽  
Dystrophic Axons ◽  
The Brain ◽  
Nucleus Cuneatus

Although neuroaxonal dystrophy (NAD) has been examined by light and electron microscopy for years, the nature of the components in the dystrophic axons is not well understood. The present report examines nucleus gracilis and cuneatus (the dorsal column nuclei) in the brain stem of aging mice.Mice (C57BL/6J) were sacrificed by aldehyde perfusion at ages ranging from 3 months to 23 months. Several brain areas and parts of other organs were processed for electron microscopy.At 3 months of age, very little evidence of NAD can be discerned by light microscopy. At the EM level, a few axons are found to contain dystrophic material. By 23 months of age, the entire nucleus gracilis is filled with dystrophic axons. Much less NAD is seen in nucleus cuneatus by comparison. The most recurrent pattern of NAD is an enlarged profile, in the center of which is a mass of reticulated material (reticulated portion; or RP).

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