scholarly journals A closed-loop human simulator for investigating the role of feedback control in brain-machine interfaces

2011 ◽  
Vol 105 (4) ◽  
pp. 1932-1949 ◽  
Author(s):  
John P. Cunningham ◽  
Paul Nuyujukian ◽  
Vikash Gilja ◽  
Cindy A. Chestek ◽  
Stephen I. Ryu ◽  
...  
Keyword(s):  
Feedback Control ◽  
Neural Activity ◽  
High Performance ◽  
Closed Loop ◽  
Critical Role ◽  
Healthy Human ◽  
Neural Prosthetic ◽  
Decoding Algorithms ◽  
Current State

Neural prosthetic systems seek to improve the lives of severely disabled people by decoding neural activity into useful behavioral commands. These systems and their decoding algorithms are typically developed “offline,” using neural activity previously gathered from a healthy animal, and the decoded movement is then compared with the true movement that accompanied the recorded neural activity. However, this offline design and testing may neglect important features of a real prosthesis, most notably the critical role of feedback control, which enables the user to adjust neural activity while using the prosthesis. We hypothesize that understanding and optimally designing high-performance decoders require an experimental platform where humans are in closed-loop with the various candidate decode systems and algorithms. It remains unexplored the extent to which the subject can, for a particular decode system, algorithm, or parameter, engage feedback and other strategies to improve decode performance. Closed-loop testing may suggest different choices than offline analyses. Here we ask if a healthy human subject, using a closed-loop neural prosthesis driven by synthetic neural activity, can inform system design. We use this online prosthesis simulator (OPS) to optimize “online” decode performance based on a key parameter of a current state-of-the-art decode algorithm, the bin width of a Kalman filter. First, we show that offline and online analyses indeed suggest different parameter choices. Previous literature and our offline analyses agree that neural activity should be analyzed in bins of 100- to 300-ms width. OPS analysis, which incorporates feedback control, suggests that much shorter bin widths (25–50 ms) yield higher decode performance. Second, we confirm this surprising finding using a closed-loop rhesus monkey prosthetic system. These findings illustrate the type of discovery made possible by the OPS, and so we hypothesize that this novel testing approach will help in the design of prosthetic systems that will translate well to human patients.

The critical role of materials metrology in engineering

1987 ◽  
Vol 322 (1567) ◽  
pp. 361-372
Keyword(s):  
High Performance ◽  
Critical Role ◽  
Test Procedures ◽  
Engineering Structures ◽  
Codes Of Practice ◽  
Materials Research ◽  
Future Technologies ◽  
Industrial Needs ◽  
Industrial Standards

This paper analyses the critical underpinning role of materials research and testing for contemporary engineering and future technologies. It is obvious that measurements, tests and evaluations of materials and components, i.e. materials metrologies, are crucial to provide the information and data needed to optimize the function of engineering structures. The industrial needs and research trends in materials metrology are reviewed, and recent BAM-developments of measuring techniques for high-technology sectors, like high-temperature technology or high-performance ceramics, are presented. Finally, the relevance of an appropriate metrological base for the establishment of industrial standards, agreed codes of practice and the harmonization of test procedures for the international trade of technical products is discussed.

Critical role of atomic-scale defect disorders for high-performance nanostructured half-Heusler thermoelectric alloys and their thermal stability

2019 ◽  
Vol 180 ◽  
pp. 97-104 ◽  
Author(s):  
Ho Jae Lee ◽  
Kyu Hyoung Lee ◽  
Liangwei Fu ◽  
GyeongTak Han ◽  
Hyun-Sik Kim ◽  
...  
Keyword(s):  
Thermal Stability ◽  
High Performance ◽  
Critical Role ◽  
Atomic Scale

scholarly journals A Review on the Role of the Neuroscience of Flow States in the Modern World

2020 ◽  
Vol 10 (9) ◽  
pp. 137
Author(s):  
Joshua Gold ◽  
Joseph Ciorciari
Keyword(s):  
Skill Acquisition ◽  
High Performance ◽  
Peak Performance ◽  
Modern World ◽  
General Technique ◽  
Current State ◽  
Novel Method ◽  
Overall Performance ◽  
Flow States

Flow states have been shown to help people reach peak performance, yet this elusive state is not easily attained. The review describes the current state of literature on flow by addressing the environmental influences as well as the cognitive and neurocognitive elements that underlie the experience. In particular, the research focusses on the transition of cognitive control from an explicit to an implicit process. This is further expanded upon to look at the current, yet related neurocognitive research of high performance associated with the implicit process of automaticity. Finally, the review focusses on transcranial direct current stimulation (tDCS) as a novel method to facilitates an induction of flow states. Implications are aimed at a general technique to improve on skill acquisition and overall performance.

N-Glycosylation of IgG and IgG-Like Recombinant Therapeutic Proteins: Why Is It Important and How Can We Control It?

2020 ◽  
Vol 11 (1) ◽  
pp. 311-338 ◽  
Author(s):  
Natalia I. Majewska ◽  
Max L. Tejada ◽  
Michael J. Betenbaugh ◽  
Nitin Agarwal
Keyword(s):  
Posttranslational Modifications ◽  
Critical Role ◽  
Process Conditions ◽  
Current State ◽  
Pharmacokinetic Properties ◽  
Regulatory Bodies ◽  
Nucleotide Sugars ◽  
Analytical Approaches ◽  
Advanced Glycosylation

Regulatory bodies worldwide consider N-glycosylation to be a critical quality attribute for immunoglobulin G (IgG) and IgG-like therapeutics. This consideration is due to the importance of posttranslational modifications in determining the efficacy, safety, and pharmacokinetic properties of biologics. Given its critical role in protein therapeutic production, we review N-glycosylation beginning with an overview of the myriad interactions of N-glycans with other biological factors. We examine the mechanism and drivers for N-glycosylation during biotherapeutic production and the several competing factors that impact glycan formation, including the abundance of precursor nucleotide sugars, transporters, glycosidases, glycosyltransferases, and process conditions. We explore the role of these factors with a focus on the analytical approaches used to characterize glycosylation and associated processes, followed by the current state of advanced glycosylation modeling techniques. This combination of disciplines allows for a deeper understanding of N-glycosylation and will lead to more rational glycan control.

Sovereign Wealth Funds and the Global Political Economy of Trust and Legitimacy

2017 ◽  
Author(s):  
Gordon L. Clark ◽  
Adam D. Dixon
Keyword(s):  
Political Economy ◽  
Critical Role ◽  
Regulatory Regime ◽  
Sovereign Wealth Funds ◽  
Global Political Economy ◽  
Form And Function ◽  
Current State ◽  
And Function

This chapter unpacks the concepts of trust and legitimacy as they pertain to sovereign funds in the global political economy. Its argument is divided into three parts. First, the importance of trust in finance and geopolitics, and the critical role of transparency, and how this relates to sovereign funds. Second, the legitimacy of sovereign funds at home and abroad in general with particular reference to how the regulatory regime surrounding public institutional investors in developed democracies is emulated in the Santiago Principles, and why it is significant for understanding the legitimacy of sovereign funds. Third, the current state of trust and legitimacy for sovereign funds is evaluated, with an explanation of why the continued opacity of some sovereign funds has not reduced trustworthiness. The chapter concludes on a speculative note, suggesting that the expected institutional form and function of sovereign funds may be at odds with the long-term interests of their state-sponsors.

scholarly journals Variability in locomotor dynamics reveals the critical role of feedback in task control

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Ismail Uyanik ◽  
Shahin Sefati ◽  
Sarah A Stamper ◽  
Kyoung-A Cho ◽  
M Mert Ankarali ◽  
...  
Keyword(s):  
System Dynamics ◽  
Closed Loop ◽  
Critical Role ◽  
Tracking Task ◽  
Behavioral Performance ◽  
Task Control ◽  
Neural Controllers ◽  
Eigenmannia Virescens ◽  
The Impact

Animals vary considerably in size, shape, and physiological features across individuals, but yet achieve remarkably similar behavioral performances. We examined how animals compensate for morphophysiological variation by measuring the system dynamics of individual knifefish (Eigenmannia virescens) in a refuge tracking task. Kinematic measurements of Eigenmannia were used to generate individualized estimates of each fish’s locomotor plant and controller, revealing substantial variability between fish. To test the impact of this variability on behavioral performance, these models were used to perform simulated ‘brain transplants’—computationally swapping controllers and plants between individuals. We found that simulated closed-loop performance was robust to mismatch between plant and controller. This suggests that animals rely on feedback rather than precisely tuned neural controllers to compensate for morphophysiological variability.

Critical role of EphA3 in cancer and current state of EphA3 drug therapeutics

2020 ◽  
Vol 47 (7) ◽  
pp. 5523-5533 ◽  
Author(s):  
Max London ◽  
Eugenio Gallo
Keyword(s):  
Critical Role ◽  
Current State

scholarly journals Variability in Locomotor Dynamics Reveals the Critical Role of Feedback in Task Control

2019 ◽  
Author(s):  
Ismail Uyanik ◽  
Shahin Sefati ◽  
Sarah A. Stamper ◽  
Kyoung-A Cho ◽  
M. Mert Ankarali ◽  
...  
Keyword(s):  
System Dynamics ◽  
Closed Loop ◽  
Critical Role ◽  
Tracking Task ◽  
Behavioral Performance ◽  
Task Control ◽  
Neural Controllers ◽  
Eigenmannia Virescens ◽  
The Impact

AbstractAnimals vary considerably in size, shape, and physiological features across individuals, but yet achieve behavioral performances that are virtually indistinguishable between conspecifics. We examined how animals compensate for morphophysiological variation by measuring the system dynamics of individual knifefish (Eigenmannia virescens) in a refuge tracking task. Kinematic measurements of Eigenmannia were used to generate individualized estimates of each fish’s locomotor plant and controller revealing substantial variability between fish. To test the impact of this variability on behavioral performance, these models were used to perform simulated ‘brain transplants’—computationally swapping controllers and plants between individuals. We found that simulated closed-loop performance was robust to mismatch between plant and controller. This suggests that animals rely on feedback rather than precisely tuned neural controllers to compensate for morphophysiological variability.

scholarly journals Isoflurane-Induced Burst Suppression Is a Thalamus-Modulated, Focal-Onset Rhythm With Persistent Local Asynchrony and Variable Propagation Patterns in Rats

2021 ◽  
Vol 14 ◽  
Author(s):  
Qianwen Ming ◽  
Jyun-You Liou ◽  
Fan Yang ◽  
Jing Li ◽  
Chaojia Chu ◽  
...  
Keyword(s):  
Neural Activity ◽  
High Speed ◽  
Critical Role ◽  
Burst Suppression ◽  
Propagating Waves ◽  
Inhalational Anesthetic ◽  
Highly Correlated ◽  
Subsequent Propagation ◽  
Global Brain

Background: Inhalational anesthetic-induced burst suppression (BS) is classically considered a bilaterally synchronous rhythm. However, local asynchrony has been predicted in theoretical studies and reported in patients with pre-existing focal pathology.Method: We used high-speed widefield calcium imaging to study the spatiotemporal dynamics of isoflurane-induced BS in rats.Results: We found that isoflurane-induced BS is not a globally synchronous rhythm. In the neocortex, neural activity first emerged in a spatially shifting, variably localized focus. Subsequent propagation across the whole cortex was rapid, typically within <100 milliseconds, giving the superficial resemblance to global synchrony. Neural activity remained locally asynchronous during the bursts, forming complex recurrent propagating waves. Despite propagation variability, spatial sequences of burst propagation were largely preserved between the hemispheres, and neural activity was highly correlated between the homotopic areas. The critical role of the thalamus in cortical burst initiation was demonstrated by using unilateral thalamic tetrodotoxin injection.Conclusion: The classical impression that anesthetics-induced BS is a state of global brain synchrony is inaccurate. Bursts are a series of shifting local cortical events facilitated by thalamic projection that unfold as rapid, bilaterally asynchronous propagating waves.

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