Ketamine disrupts theta synchrony across the septotemporal axis of the CA1 region of hippocampus

2013 ◽  
Vol 109 (2) ◽  
pp. 570-579 ◽  
Author(s):  
James R. Hinman ◽  
Stephanie C. Penley ◽  
Monty A. Escabí ◽  
James J. Chrobak
Keyword(s):  
Hippocampal Neurons ◽  
Nmda Antagonist ◽  
Locomotor Behavior ◽  
Past Experience ◽  
Global Network ◽  
Low Doses ◽  
Theta Power ◽  
Ca1 Region ◽  
Hippocampal Theta ◽  
The Relationship

The hippocampal theta signal reflects moment-to-moment variation in the synchrony of synaptic input to hippocampal neurons. Consistent with the topography of hippocampal afferents, the synchrony (coherence) of the theta signal varies across the septotemporal axis. Septotemporal variation in the theta signal can also be observed in relation to ongoing and past experience. Thus there is a systematic decrease in the relationship between locomotor speed and theta power across the septotemporal axis, septal hippocampus exhibiting the strongest relationship. Conversely, theta in temporal hippocampus decrements over repeated behavioral experience (running episodes), while theta in the septal hippocampus does not. Ketamine is an N-methyl-d-aspartate (NMDA) antagonist that can decrease theta power. The present study examined whether ketamine treatment could alter theta coherence across the long axis independent of changes in locomotor behavior. Rats were well trained to navigate a linear runway and outfitted with electrodes at different septotemporal positions within CA1. Locomotor behavior and theta coherence and power were examined after administration of 2.5 and 10 mg/kg ketamine. Ketamine (2.5 mg/kg) decreased theta coherence between distant CA1 electrode sites without altering running speed or theta power. Both doses of ketamine also blunted and reversed the decrement in theta power observed at midseptotemporal and temporal electrodes over repeated run sessions. The results demonstrate the sensitivity of global network synchronization to relatively low doses of ketamine and septotemporal differences in the influence of ketamine on hippocampal dynamics in relation to past experience.

Document- and Keyword-based Author Co-citation Analysis

2018 ◽  
Vol 2 (2) ◽  
pp. 70-82 ◽  
Author(s):  
Binglu Wang ◽  
Yi Bu ◽  
Win-bin Huang
Keyword(s):  
Citation Analysis ◽  
Semantic Similarity ◽  
Method Validation ◽  
New Method ◽  
Global Network ◽  
Network Visualization ◽  
Knowledge Domain ◽  
Knowledge Domains ◽  
Domain Mapping ◽  
The Relationship

AbstractIn the field of scientometrics, the principal purpose for author co-citation analysis (ACA) is to map knowledge domains by quantifying the relationship between co-cited author pairs. However, traditional ACA has been criticized since its input is insufficiently informative by simply counting authors’ co-citation frequencies. To address this issue, this paper introduces a new method that reconstructs the raw co-citation matrices by regarding document unit counts and keywords of references, named as Document- and Keyword-Based Author Co-Citation Analysis (DKACA). Based on the traditional ACA, DKACA counted co-citation pairs by document units instead of authors from the global network perspective. Moreover, by incorporating the information of keywords from cited papers, DKACA captured their semantic similarity between co-cited papers. In the method validation part, we implemented network visualization and MDS measurement to evaluate the effectiveness of DKACA. Results suggest that the proposed DKACA method not only reveals more insights that are previously unknown but also improves the performance and accuracy of knowledge domain mapping, representing a new basis for further studies.

Understanding the Implementation of IT Governance Arrangements and IT Infrastructure Using Actor Network Theory

2016 ◽  
Vol 8 (2) ◽  
pp. 44-55
Author(s):  
Hafizah Mohamad Hsbollah ◽  
Alan Simon ◽  
Nick Letch
Keyword(s):  
Information Systems ◽  
Network Theory ◽  
It Governance ◽  
Actor Network Theory ◽  
Global Network ◽  
It Infrastructure ◽  
Network Approach ◽  
Actor Network ◽  
The Relationship ◽  
Governance Arrangements

The implementation of IT governance (ITG) arrangements and its relationship to IT infrastructure has not received much attention in either the ITG or the information systems (IS) literature. Based on the premise that the foundation on which ITG is implemented lies in the interaction between ITG arrangements of structures, processes and relational mechanisms and IT infrastructure, the authors present a discussion of how actor network theory (ANT) can be used as an overarching theoretical framework of explanation. The authors propose a model of ITG implementation and discuss how ANT, in particular the local/global network approach, can be applied to understand the relationship that exists between ITG arrangements and IT infrastructure.

scholarly journals Age-Related Cognitive Impairment: Role of Reduced Synaptobrevin-2 Levels in Deficits of Memory and Synaptic Plasticity

2019 ◽  
Vol 75 (9) ◽  
pp. 1624-1632 ◽  
Author(s):  
Albert Orock ◽  
Sreemathi Logan ◽  
Ferenc Deak
Keyword(s):  
Cognitive Impairment ◽  
Synaptic Plasticity ◽  
Learning And Memory ◽  
Hippocampal Neurons ◽  
Long Term Potentiation ◽  
Receptor Protein ◽  
Protein Levels ◽  
Ca1 Region ◽  
Age Related ◽  
Term Potentiation

AbstractCognitive impairment in the aging population is quickly becoming a health care priority, for which currently no disease-modifying treatment is available. Multiple domains of cognition decline with age even in the absence of neurodegenerative diseases. The cellular and molecular changes leading to cognitive decline with age remain elusive. Synaptobrevin-2 (Syb2), the major vesicular SNAP receptor protein, highly expressed in the cerebral cortex and hippocampus, is essential for synaptic transmission. We have analyzed Syb2 protein levels in mice and found a decrease with age. To investigate the functional consequences of lower Syb2 expression, we have used adult Syb2 heterozygous mice (Syb2+/−) with reduced Syb2 levels. This allowed us to mimic the age-related decrease of Syb2 in the brain in order to selectively test its effects on learning and memory. Our results show that Syb2+/− animals have impaired learning and memory skills and they perform worse with age in the radial arm water maze assay. Syb2+/− hippocampal neurons have reduced synaptic plasticity with reduced release probability and impaired long-term potentiation in the CA1 region. Syb2+/− neurons also have lower vesicular release rates when compared to WT controls. These results indicate that reduced Syb2 expression with age is sufficient to cause cognitive impairment.

Personal networks and psychological attributes: Exploring individual differences in personality and sense of community and their relationship to the structure of personal networks

2019 ◽  
Vol 8 (2) ◽  
pp. 168-188 ◽  
Author(s):  
Isidro Maya-Jariego ◽  
Srebrenka Letina ◽  
Elena González Tinoco
Keyword(s):  
Personality Traits ◽  
Sense Of Community ◽  
Personal Networks ◽  
Global Network ◽  
Personal Network ◽  
Ego Networks ◽  
Network Measures ◽  
Psychological Attributes ◽  
Psychological Differences ◽  
The Relationship

AbstractThe paper explores the relationship between personality characteristics, sense of community and the structure of personal networks. We collected personal network data from 100 adults, consisting of the information about their 45 alters and ties among them. In addition to the typically used bivariate correlations to analyze the relationship between individual psychological differences and network structure, we propose first the use of typologies of networks and personality and second modified versions of the triadic census in ego-networks. The results show that different personality types tend to occupy a different kind of networks and that newly introduced triadic measures show a relatively higher association with examined psychological attributes than global network measures. Overall, the Psychological Sense of Community showed higher associations with network measures than Big Five personality traits. The former was positively correlated with measures of closed triads among alters, but also with alters embedded in triads with weak ties. Regarding personality traits, Emotional Stability was positively correlated with strong closed triads and with the overall indicator of density. The elaboration of typologies and the census of triads are shown to be effective strategies for the description of personal networks, as well as for the analysis of individual psychological differences.

Theta power and theta-gamma coupling support spatial memory retrieval

2019 ◽  
Author(s):  
Umesh Vivekananda ◽  
Daniel Bush ◽  
James A Bisby ◽  
Sallie Baxendale ◽  
Roman Rodionov ◽  
...  
Keyword(s):  
Spatial Memory ◽  
Task Performance ◽  
Memory Function ◽  
Memory Task ◽  
Theta Oscillations ◽  
Theta Power ◽  
Human Epilepsy ◽  
Phase Amplitude ◽  
Hippocampal Theta

AbstractHippocampal theta oscillations have been implicated in spatial memory function in both rodents and humans. What is less clear is how hippocampal theta interacts with higher frequency oscillations during spatial memory function, and how this relates to subsequent behaviour. Here we asked ten human epilepsy patients undergoing intracranial EEG recording to perform a desk-top virtual reality spatial memory task, and found that increased theta power in two discrete bands (‘low’ 2-5Hz and ‘high’ 6-9Hz) during cued retrieval was associated with improved task performance. Similarly, increased coupling between ‘low’ theta phase and gamma amplitude during the same period was associated with improved task performance. These results support a role of theta oscillations and theta-gamma phase-amplitude coupling in human spatial memory function.

May Grace Abound: Making God’s Grace Cognitively Salient May Increase Reparative Action

2019 ◽  
Vol 48 (3) ◽  
pp. 218-228 ◽  
Author(s):  
Rodney L. Bassett ◽  
Sarah Scott ◽  
Renee Blodgett ◽  
Mika Barnhart ◽  
Noelle Batterson ◽  
...  
Keyword(s):  
College Students ◽  
Process Modeling ◽  
Focus Of Attention ◽  
Past Experience ◽  
Dual Process ◽  
Christian College ◽  
Control Intervention ◽  
God's Grace ◽  
The Relationship ◽  
Reparative Action

A study was done with Christian college students to determine the relationship between grace salience, remorse, and reparative action in the context of a past transgression. Grace salience involves the process of making God’s grace cognitively prominent. In the context of dual-process modeling, grace salience involves making the construct of God’s grace cognitively explicit and the focus of attention for an individual. Participants recalled a past experience where they harmed someone. Before the grace salience or control intervention, there were no differences in desire for reparative action and guilt or shame self-statements. However, after the intervention, compared to the control, the grace salience intervention produced a greater desire for reparative action and greater tendency to agree with guilt self-statements. When feelings of remorse were assessed after the experimental manipulations, higher levels of sorrow and brokenness predicted greater desire for reparative action, higher levels of shame and brokenness predicted higher agreement with shame self-statements, and higher levels of guilt and brokenness predicted greater agreement with guilt self-statements.

Bottom up: a UK approach to art library co-operation

1998 ◽  
Vol 23 (4) ◽  
pp. 9-17
Author(s):  
Beth Houghton
Keyword(s):  
Local Level ◽  
Past Experience ◽  
National Strategy ◽  
Crystal Ball ◽  
Bottom Up ◽  
The Relationship ◽  
Operative Activity ◽  
Successes And Failures

What is library co-operation, what is its current relevance and how is its nature and purpose changing in today’s information world? What are the particular types of co-operative activity that art librarians have taken part in, and what have been their successes and failures? This article examines a range of projects carried out by ARLIS/UK & Ireland and others, from directories and union lists to cataloguing and indexing and disposal of stock. It considers the relationship between cooperative initiatives which can best be undertaken at local level and those where a national strategy and infrastructure are necessary. Finally it draws practical and realistic conclusions from a combination of past experience and a little crystal ball gazing.

Manufacturing network integration and culture: an institution-based view

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Maricela C. Arellano ◽  
Cristina Sancha ◽  
Torbjørn Netland ◽  
Cristina Gimenez Thomsen
Keyword(s):  
Organizational Culture ◽  
Cultural Dimensions ◽  
Global Network ◽  
Institutional Environments ◽  
Network Integration ◽  
Content Type ◽  
Study Results ◽  
Manufacturing Network ◽  
The Relationship

PurposeIn pursuit of increased competitiveness, global manufacturers often seek tighter integration among the plants in their production networks. However, this is a challenging task because plants are dispersed across multiple institutional environments. Although the literature provides abundant evidence of how formal institutional environments affect the integration among plants, little is known about the role of the informal institutional environment – such as culture. In this study, the authors investigate the relationship between different dimensions of culture and manufacturing network integration.Design/methodology/approachThe authors combine survey data from the most recent International Manufacturing Strategy Survey with secondary data that capture cultural dimensions. They then analyze the responses from 581 assembly plants in 21 countries obtained from the survey using a multilevel regression model.FindingsThe study results show that plants located in masculine and long-term-oriented national cultures are associated with lower levels of integration with other plants. The results for the other four Hofstede dimensions of national culture were not statistically significant. At the level of organizational culture, the authors found that a collaborative plant environment positively relates to higher levels of network integration. They did not find statistically significant evidence for the relationship between cultural or geographical distance and network integration.Practical implicationsThis research provides managers with practical insights into the types and combinations of cultural environments that affect the integration of plants in a global network. This knowledge is useful for informing effective integration strategies and tactics.OriginalityThe authors provide new, empirical evidence of the relation between the informal institutional environments of a plant and its integration in a manufacturing network. Drawing on an institution-based view, they contribute to the literature on manufacturing networks by discussing and testing empirically the role of national and organizational culture in network integration.

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