scholarly journals Biophysical and Architectural Mechanisms of Subthalamic Theta under Response Conflict

2021 ◽  
Author(s):  
Prannath Moolchand ◽  
Stephanie R. Jones ◽  
Michael J. Frank
Keyword(s):  
Large Scale ◽  
Response Conflict ◽  
Empirical Literature ◽  
Theta Band ◽  
Cortical Input ◽  
Theta Power ◽  
Cortical Motor ◽  
Selection Dynamics ◽  
Rhythmic Burst ◽  
Globus Pallidus Externus

The cortico-basal ganglia circuit is needed to suppress prepotent actions and to facilitate controlled behavior. Under conditions of response conflict, the frontal cortex and subthalamic nucleus [STN] exhibit increased spiking and theta band power, which are linked to adaptive regulation of behavioral output. The electrophysiological mechanisms underlying these neural signatures of impulse control remain poorly understood. To address this lacuna, we constructed a novel large-scale, biophysically principled model of the subthalamopallidal [STN-Globus Pallidus externus (GPe)] network, and examined the mechanisms that modulate theta power and spiking in response to cortical input. Simulations confirmed that theta power does not emerge from intrinsic network dynamics but is robustly elicited in response to cortical input as burst events representing action selection dynamics. Rhythmic burst events of multiple cortical populations, representing a state of conflict where cortical motor plans vacillate in the theta range, led to prolonged STN theta and increased spiking, consistent with empirical literature. Notably, theta band signaling required NMDA, but not AMPA, currents, which were in turn related to a triphasic STN response characterized by spiking, silence and bursting periods. Finally, theta band resonance was also strongly modulated by architectural connectivity, with maximal theta arising when multiple cortical populations project to individual STN "conflict detector" units, due to an NMDA-dependent supralinear response. Our results provide insights into the biophysical principles and architectural constraints that give rise to STN dynamics during response conflict, and how their disruption can lead to impulsivity and compulsivity.

scholarly journals Oscillatory Mechanisms of Response Conflict Elicited by Color and Motion Direction: An Individual Differences Approach

2018 ◽  
Vol 30 (4) ◽  
pp. 468-481 ◽  
Author(s):  
Marlies E. Vissers ◽  
K. Richard Ridderinkhof ◽  
Michael X. Cohen ◽  
Heleen A. Slagter
Keyword(s):  
Individual Differences ◽  
Phase Synchronization ◽  
Simon Task ◽  
Response Conflict ◽  
Large Individual ◽  
Theta Band ◽  
Motion Direction ◽  
Stimulus Color ◽  
Theta Power ◽  
Feature Dimension

Goal-directed behavior requires control over automatic behavior, for example, when goal-irrelevant information from the environment captures an inappropriate response and conflicts with the correct, goal-relevant action. Neural oscillations in the theta band (∼6 Hz) measured at midfrontal electrodes are thought to form an important substrate of the detection and subsequent resolution of response conflict. Here, we examined the extent to which response conflict and associated theta-band activity depend on the visual stimulus feature dimension that triggers the conflict. We used a feature-based Simon task to manipulate conflict by motion direction and stimulus color. Analyses were focused on individual differences in behavioral response conflict elicited across different stimulus dimensions and their relationship to conflict-related midfrontal theta. We first confirmed the presence of response conflict elicited by task-irrelevant motion and stimulus color, demonstrating the usefulness of our modified version of the Simon task to assess different sensory origins of response conflict. Despite titrating overall task performance, we observed large individual differences in the behavioral manifestations of response conflict elicited by the different visual dimensions. These behavioral conflict effects were mirrored in a dimension-specific relationship with conflict-related midfrontal theta power, such that, for each dimension, individual midfrontal theta power was generally higher when experienced response conflict was high. Finally, exploratory analyses of interregional functional connectivity suggested a role for phase synchronization between frontal and parietal scalp sites in modulating experienced conflict when color was the task-relevant visual dimension. Highlighting the importance of an individual differences approach in cognitive neuroscience, these results reveal large individual differences in experienced response conflict depending on the source of visual interference, which are predicted by conflict-related midfrontal theta power.

The Impact of Quantitative Easing on Emerging Markets – Literature Review

e-Finanse ◽  
2018 ◽  
Vol 14 (4) ◽  
pp. 67-76
Author(s):  
Piotr Bartkiewicz
Keyword(s):  
Emerging Markets ◽  
Large Scale ◽  
Empirical Literature ◽  
Quantitative Easing ◽  
Methodological Choices ◽  
The Subject ◽  
Methodological Approaches ◽  
The Impact ◽  
Sufficient Precision

AbstractThe article presents the results of the review of the empirical literature regarding the impact of quantitative easing (QE) on emerging markets (EMs). The subject is of interest to policymakers and researchers due to the increasingly larger role of EMs in the world economy and the large-scale capital flows occurring after 2009. The review is conducted in a systematic manner and takes into consideration different methodological choices, samples and measurement issues. The paper puts the summarized results in the context of transmission channels identified in the literature. There are few distinct methodological approaches present in the literature. While there is a consensus regarding the direction of the impact of QE on EMs, its size and durability have not yet been assessed with sufficient precision. In addition, there are clear gaps in the empirical findings, not least related to relative underrepresentation of the CEE region (in particular, Poland).

scholarly journals DUPLICITY IN REGULATION AND PERFORMANCE OF THE FINANCIAL SECTOR IN KENYA

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Dr.Agnes Ogada
Keyword(s):  
Large Scale ◽  
Developing Economies ◽  
Financial Sector ◽  
The United States ◽  
Empirical Literature ◽  
Unique Contribution ◽  
Regulatory Structure ◽  
The Public ◽  
And Performance ◽  
The Uk

Purpose: The objective of the study was to investigate the duplicity in regulation and its effect on performance of the financial sector in Kenya. The specific objectives were; to review and identify regulation duplication/competition in existing regulatory framework for the financial sector in Kenya; to describe how regulatory effectiveness has been measured in empirical literature; to assess whether the current regulatory structure has affected the performance of the financial sector in Kenya and lastly to suggest potential ways of enhancing regulatory effectiveness in Kenya. Methodology: The paper used a desk study review methodology where relevant empirical literature was reviewed to identify main themes and to extract knowledge gaps. Findings: The study found out that financial sector in Kenya and other developing economies have reported losses on a large scale due to under regulation and regulator duplicity. Some of these have become insolvent, or have had to be taken over or rescued by their governments. A single market regulator clearly has its own advantages over multiple regulators. But it is more suitable for well-developed and mature markets which are smaller in size, like the UK. The study also found out that Kenya’s economy and political arena are not mature enough to handle a single financial market regulator. In this light it can be asserted that even mature economies such as the United States still have multiple regulators. Unique contribution to theory, practice and policy: Adherence to principles of open government, including transparency and participation in the regulatory process to ensure that regulation serves the public interest and is informed by the legitimate needs of those interested in and affected by regulation. Governments should ensure that regulations are comprehensible and clear and that parties can easily understand their rights and obligations. Organizations should create personalized technology systems that create a demand adaptation of ICT at every level of the organizational operations

scholarly journals The Empirical Structure of Narrative Identity: The Initial Big Three

2019 ◽  
Author(s):  
Kate C. McLean ◽  
Moin Syed ◽  
Monisha Pasupathi ◽  
Jonathan M. Adler ◽  
William Lewis Dunlop ◽  
...  
Keyword(s):  
Large Scale ◽  
Narrative Identity ◽  
Functional Model ◽  
Well Being ◽  
Empirical Literature ◽  
Life Narratives ◽  
Current Field ◽  
Latent Factors ◽  
Robust Model ◽  
Structural Aspects

A robust empirical literature suggests that individual differences in the thematic and structural aspects of life narratives are associated with and predictive of psychological well-being. However, one limitation of the current field is the multitude of ways of capturing these narrative features, with little attention to overarching dimensions or latent factors of narrative that are responsible for these associations with well-being. In the present study we uncovered a reliable structure that accommodates commonly studied features of life narratives in a large-scale, multi-University collaborative effort. Across three large samples of emerging and mid-life adults responding to various narrative prompts (N = 855 participants, N = 2565 narratives), we found support for three factors of life narratives: motivational and affective themes, autobiographical reasoning, and structural aspects. We also identified a “functional” model of these three factors that reveals a reduced set of narrative features that adequately captures each factor. Additionally, motivational and affective themes was the factor most reliably related to well-being. Finally, associations with personality traits were variable by narrative prompt. Overall, the present findings provide a comprehensive and robust model for understanding the empirical structure of narrative identity as it relates to well-being, which offers meaningful theoretical contributions to the literature, and facilitates practical decision making for researchers endeavoring to capture and quantify life narratives.

Research Challenges and Opportunities in Conducting Quantitative Studies on Large-Scale Agile Methodology

2020 ◽  
Vol 31 (2) ◽  
pp. 64-73
Author(s):  
Dinesh Batra
Keyword(s):  
Large Scale ◽  
Empirical Literature ◽  
Adoption Studies ◽  
Agile Methodology ◽  
Quantitative Studies ◽  
Balanced Approach ◽  
Research Challenges ◽  
Time Period ◽  
Dependent Variables ◽  
Challenges And Opportunities

This research note suggests five research challenges when conducting quantitative studies on large-scale agile methodology (LSAM). First, the LSAM empirical literature, which is mainly characterized by qualitative studies primarily focusing on coordination issues, provides limited background. Second, the notion of “large” in LSAM needs to be clarified because the existing research seems to have focused on “very large” or outlier projects. Third, the popular LSAM methods suggest broad and general maxims that may result in difficulty in operationalizing dependent variables, especially in innovation adoption studies. Fourth, the researcher may get overwhelmed when selecting independent variables from the plethora of suggested constructs. Finally, some of the problems associated with large-scale agile are mostly challenges of using conventional agile during a time-period when LSAM had not formally emerged. Researchers should take a balanced approach considering both benefits and challenges of using LSAM and focusing on project-level dependent measures such as success and acceptance.

Dexterous Hand Movements and Their Recovery After Central Nervous System Injury

2019 ◽  
Vol 42 (1) ◽  
pp. 315-335 ◽  
Author(s):  
Tadashi Isa
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Large Scale ◽  
Therapeutic Strategies ◽  
Central Nervous System Injury ◽  
Hand Movements ◽  
Recovery Model ◽  
Cortical Motor ◽  
Hand Dexterity ◽  
Dexterous Hand

Hand dexterity has uniquely developed in higher primates and is thought to rely on the direct corticomotoneuronal (CM) pathway. Recent studies have shown that rodents and carnivores lack the direct CM pathway but can control certain levels of dexterous hand movements through various indirect CM pathways. Some homologous pathways also exist in higher primates, and among them, propriospinal (PrS) neurons in the mid-cervical segments (C3-C4) are significantly involved in hand dexterity. When the direct CM pathway was lesioned caudal to the PrS and transmission of cortical commands to hand motoneurons via the PrS neurons remained intact, dexterous hand movements could be significantly recovered. This recovery model was intensively studied, and it was found that, in addition to the compensation by the PrS neurons, a large-scale reorganization in the bilateral cortical motor-related areas and mesolimbic structures contributed to recovery. Future therapeutic strategies should target these multihierarchical areas.

scholarly journals Measuring Discretion and Delegation in Legislative Texts: Methods and Application to US States

2020 ◽  
Vol 29 (1) ◽  
pp. 43-57 ◽  
Author(s):  
Matia Vannoni ◽  
Elliott Ash ◽  
Massimo Morelli
Keyword(s):  
Computational Linguistics ◽  
Large Scale ◽  
Cost Model ◽  
Agency Cost ◽  
Empirical Literature ◽  
State Legislation ◽  
Us States ◽  
Bureaucratic Discretion ◽  
Legal Texts ◽  
Parse Trees

Bureaucratic discretion and executive delegation are central topics in political economy and political science. The previous empirical literature has measured discretion and delegation by manually coding large bodies of legislation. Drawing from computational linguistics, we provide an automated procedure for measuring discretion and delegation in legal texts to facilitate large-scale empirical analysis. The method uses information in syntactic parse trees to identify legally relevant provisions, as well as agents and delegated actions. We undertake two applications. First, we produce a measure of bureaucratic discretion by looking at the level of legislative detail for US states and find that this measure increases after reforms giving agencies more independence. This effect is consistent with an agency cost model, where a more independent bureaucracy requires more specific instructions (less discretion) to avoid bureaucratic drift. Second, we construct measures of delegation to governors in state legislation. Consistent with previous estimates using non-text metrics, we find that executive delegation increases under unified government.

Dignitarian Hunting

2018 ◽  
Vol 44 (1) ◽  
pp. 49-73 ◽  
Author(s):  
Dan Demetriou ◽  
Bob Fischer ◽  
Keyword(s):  
Animal Rights ◽  
Large Scale ◽  
Industrial Plant ◽  
Empirical Literature ◽  
Adversarial Ethics

Faced with the choice between supporting industrial plant agriculture and hunting, Tom Regan’s rights view can be plausibly developed in a way that permits a form of hunting we call “dignitarian.” To motivate this claim, we begin by showing how the empirical literature on animal deaths in plant agriculture suggests that a non-trivial amount of hunting would not add to animal harm. We discuss how Tom Regan’s miniride principle appears to morally permit hunting in that case, and we address recent objections by Jason Hanna to environmentally-based culling that may be seen to speak against this conclusion. We then turn to dignity, which is especially salient in scenarios where harm is necessary or justifiable. We situate “dignitarian” hunting within a larger framework of adversarial ethics, and argue that dignitarian hunting gives animals a more dignified death than the alternatives endemic to large-scale plant agriculture, and so is permissible based on the kinds of principles that Regan endorses. Indeed, dignitarian hunting may actually fit better with Regan’s widely endorsed animal rights framework than the practice of many vegans, and should only be rejected if we’re just as willing to condemn supporting conventional plant agriculture.

scholarly journals Efficacy of Acupuncture for Health Conditions in Children: A Review

2008 ◽  
Vol 8 ◽  
pp. 670-682 ◽  
Author(s):  
Jean Libonate ◽  
Subhadra Evans ◽  
Jennie C. I. Tsao
Keyword(s):  
Neurological Disorders ◽  
Large Scale ◽  
Health Conditions ◽  
Empirical Literature ◽  
Efficacy And Safety ◽  
Methodological Issues ◽  
Control Groups ◽  
Limited Sample ◽  
Randomized Controlled ◽  
Childhood Problems

Acupuncture has been used to treat a variety of childhood problems; however, the efficacy and safety of pediatric acupuncture remains unclear. This article reviews the existing empirical literature relating to the use of acupuncture for medical conditions in children. A systematic search of the literature revealed that acupuncture has been used to treat five main conditions in children, including pain, nocturnal enuresis, postoperative nausea/vomiting, laryngospasm/stridor, and neurological disorders. Despite a number of methodological issues, including limited sample sizes, lack of randomization, and inappropriate control groups, it is concluded that acupuncture represents a promising intervention for a variety of pediatric health conditions. To further address the safety, effectiveness, and acceptability of acupuncture in children, large-scale randomized controlled trials are needed.

scholarly journals Target amplification and distractor inhibition - Theta oscillatory dynamics of selective attention in a flanker task

2020 ◽  
Author(s):  
Céline C. Haciahmet ◽  
Christian Frings ◽  
Bernhard Pastötter
Keyword(s):  
Cluster Analysis ◽  
Selective Attention ◽  
Flanker Task ◽  
Response Conflict ◽  
Conflict Monitoring ◽  
Distractor Inhibition ◽  
Theta Power ◽  
Oscillatory Dynamics ◽  
Power Increase ◽  
Theta Frequency

Selective attention is a key mechanism to monitor conflict-related processing and behaviour, by amplifying task-relevant processing and inhibiting task-irrelevant information. Conflict monitoring and resolution is typically associated with brain oscillatory power increase in the theta frequency range (3-8 Hz), as indexed by increased midfrontal theta power. We expand previous findings of theta power increase related to conflict processing and distractor inhibition by considering attentional target amplification to be represented in theta frequency as well. The present study (N = 41) examined EEG oscillatory activities associated with stimulus and response conflict in a lateralized flanker task. Depending on the perceptual (in)congruency and response (in)compatibility of distractor-target associations, resulting stimulus and response conflicts were examined in behavioural and electrophysiological data analyses. Both response and stimulus conflict emerged in RT analysis. Regarding EEG data, response-locked cluster analysis showed an increase of midfrontal theta power related to response conflict. In addition, stimulus-locked cluster analysis revealed early clusters with increased parietal theta power for non-conflicting compared to conflicting trials, followed by increased midfrontal theta power for both stimulus and response conflict. Our results suggest that conflict resolution in the flanker task relies on a combination of target amplification, depicted by parietal theta power increase, and distractor inhibition, indexed by midfrontal theta power increase, for both stimulus and response conflicts. Attentional amplification of sensory target features is discussed with regard to a domain-general conflict monitoring account.

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