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https://www.readbyqxmd.com/read/28916520/rubrocerebellar-feedback-loop-isolates-the-interposed-nucleus-as-an-independent-processor-of-corollary-discharge-information-in-mice
#1
Christy S Beitzel, Brenda D Houck, Samantha M Lewis, Abigail L Person
Understanding cerebellar contributions to motor coordination requires deeper insight into how the output structures of the cerebellum, the cerebellar nuclei, integrate their inputs and influence downstream motor pathways. The magnocellular red nucleus (RNm), a brainstem premotor structure, is a major target of the interposed nucleus (IN), and has also been described in previous studies to send feedback collaterals to the cerebellum. Because such a pathway is in a key position to provide motor efferent information to the cerebellum, satisfying predictions about the use of corollary discharge in cerebellar computations, we studied it in mice of both sexes...
September 15, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28901195/feedforward-coordinate-control-of-a-robotic-cell-injection-catheter
#2
Weyland Cheng, Peter K Law
Remote and robotically actuated catheters are the stepping-stones toward autonomous catheters, where complex intravascular procedures may be performed with minimal intervention from a physician. This article proposes a concept for the positional, feedforward control of a robotically actuated cell injection catheter used for the injection of myogenic or undifferentiated stem cells into the myocardial infarct boundary zones of the left ventricle. The prototype for the catheter system was built upon a needle-based catheter with a single degree of deflection, a 3-D printed handle combined with actuators, and the Arduino microcontroller platform...
August 2017: Cell Transplantation
https://www.readbyqxmd.com/read/28895002/synaptic-convergence-regulates-synchronization-dependent-spike-transfer-in-feedforward-neural-networks
#3
Pachaya Sailamul, Jaeson Jang, Se-Bum Paik
Correlated neural activities such as synchronizations can significantly alter the characteristics of spike transfer between neural layers. However, it is not clear how this synchronization-dependent spike transfer can be affected by the structure of convergent feedforward wiring. To address this question, we implemented computer simulations of model neural networks: a source and a target layer connected with different types of convergent wiring rules. In the Gaussian-Gaussian (GG) model, both the connection probability and the strength are given as Gaussian distribution as a function of spatial distance...
September 12, 2017: Journal of Computational Neuroscience
https://www.readbyqxmd.com/read/28885162/adaptive-approximation-based-regulation-control-for-a-class-of-uncertain-nonlinear-systems-without-feedback-linearizability
#4
Ning Wang, Jing-Chao Sun, Min Han, Zhongjiu Zheng, Meng Joo Er
In this paper, for a general class of uncertain nonlinear (cascade) systems, including unknown dynamics, which are not feedback linearizable and cannot be solved by existing approaches, an innovative adaptive approximation-based regulation control (AARC) scheme is developed. Within the framework of adding a power integrator (API), by deriving adaptive laws for output weights and prediction error compensation pertaining to single-hidden-layer feedforward network (SLFN) from the Lyapunov synthesis, a series of SLFN-based approximators are explicitly constructed to exactly dominate completely unknown dynamics...
September 6, 2017: IEEE Transactions on Neural Networks and Learning Systems
https://www.readbyqxmd.com/read/28885146/adaptive-neural-network-control-of-a-flapping-wing-micro-aerial-vehicle-with-disturbance-observer
#5
Wei He, Zichen Yan, Changyin Sun, Yunan Chen
The research of this paper works out the attitude and position control of the flapping wing micro aerial vehicle (FWMAV). Neural network control with full state and output feedback are designed to deal with uncertainties in this complex nonlinear FWMAV dynamic system and enhance the system robustness. Meanwhile, we design disturbance observers which are exerted into the FWMAV system via feedforward loops to counteract the bad influence of disturbances. Then, a Lyapunov function is proposed to prove the closed-loop system stability and the semi-global uniform ultimate boundedness of all state variables...
October 2017: IEEE Transactions on Cybernetics
https://www.readbyqxmd.com/read/28884446/analysis-of-homeostatic-mechanisms-in-biochemical-networks
#6
Michael Reed, Janet Best, Martin Golubitsky, Ian Stewart, H Frederik Nijhout
Cell metabolism is an extremely complicated dynamical system that maintains important cellular functions despite large changes in inputs. This "homeostasis" does not mean that the dynamical system is rigid and fixed. Typically, large changes in external variables cause large changes in some internal variables so that, through various regulatory mechanisms, certain other internal variables (concentrations or velocities) remain approximately constant over a finite range of inputs. Outside that range, the mechanisms cease to function and concentrations change rapidly with changes in inputs...
September 7, 2017: Bulletin of Mathematical Biology
https://www.readbyqxmd.com/read/28867486/yap-taz-orchestrate-vegf-signaling-during-developmental-angiogenesis
#7
Xiaohong Wang, Aida Freire Valls, Géza Schermann, Ying Shen, Ivan M Moya, Laura Castro, Severino Urban, Gergely M Solecki, Frank Winkler, Lars Riedemann, Rakesh K Jain, Massimilano Mazzone, Thomas Schmidt, Tamás Fischer, Georg Halder, Carmen Ruiz de Almodóvar
Vascular endothelial growth factor (VEGF) is a major driver of blood vessel formation. However, the signal transduction pathways culminating in the biological consequences of VEGF signaling are only partially understood. Here, we show that the Hippo pathway effectors YAP and TAZ work as crucial signal transducers to mediate VEGF-VEGFR2 signaling during angiogenesis. We demonstrate that YAP/TAZ are essential for vascular development as endothelium-specific deletion of YAP/TAZ leads to impaired vascularization and embryonic lethality...
September 11, 2017: Developmental Cell
https://www.readbyqxmd.com/read/28863697/high-bandwidth-and-flexible-tracking-control-for-precision-motion-with-application-to-a-piezo-nanopositioner
#8
Zhao Feng, Jie Ling, Min Ming, Xiao-Hui Xiao
For precision motion, high-bandwidth and flexible tracking are the two important issues for significant performance improvement. Iterative learning control (ILC) is an effective feedforward control method only for systems that operate strictly repetitively. Although projection ILC can track varying references, the performance is still limited by the fixed-bandwidth Q-filter, especially for triangular waves tracking commonly used in a piezo nanopositioner. In this paper, a wavelet transform-based linear time-varying (LTV) Q-filter design for projection ILC is proposed to compensate high-frequency errors and improve the ability to tracking varying references simultaneously...
August 2017: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28855178/baroreflex-and-neurovascular-responses-to-skeletal-muscle-mechanoreflex-activation-in-humans-an-exercise-in-integrative-physiology
#9
Rachel C Drew
Cardiovascular adjustments to exercise, resulting in increased blood pressure (BP) and heart rate (HR), occur in response to activation of several neural mechanisms - the exercise pressor reflex, central command, and the arterial baroreflex. Neural inputs from these feedback and feedforward mechanisms integrate in the cardiovascular control centers in the brain stem, and modulate sympathetic and parasympathetic neural outflow, resulting in the increased BP and HR observed during exercise. Another specific consequence of the central neural integration of these inputs during exercise is increased sympathetic neural outflow directed to the kidneys, causing renal vasoconstriction, a key reflex mechanism involved in blood flow redistribution during increased skeletal muscle work...
August 30, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28842410/impaired-feedforward-control-and-enhanced-feedback-control-of-speech-in-patients-with-cerebellar-degeneration
#10
Benjamin Parrell, Zarinah Agnew, Srikantan Nagarajan, John Houde, Richard B Ivry
The cerebellum has been hypothesized to form a crucial part of the speech motor control network. Evidence for this comes from patients with cerebellar damage, who exhibit a variety of speech deficits, as well as imaging studies showing cerebellar activation during speech production in healthy individuals. To date, the precise role of the cerebellum in speech motor control remains unclear, as it has been implicated in both anticipatory (feedforward) and reactive (feedback) control. Here, we assess both anticipatory and reactive aspects of speech motor control, comparing the performance of patients with cerebellar degeneration and matched controls...
August 23, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28838469/the-unpredictive-brain-under-threat-a-neurocomputational-account-of-anxious-hypervigilance
#11
Brian R Cornwell, Marta I Garrido, Cassie Overstreet, Daniel S Pine, Christian Grillon
BACKGROUND: Anxious hypervigilance is marked by sensitized sensory-perceptual processes and attentional biases to potential danger cues in the environment. How this is realized at the neurocomputational level is unknown but could clarify the brain mechanisms disrupted in psychiatric conditions such as posttraumatic stress disorder. Predictive coding, instantiated by dynamic causal models, provides a promising framework to ground these state-related changes in the dynamic interactions of reciprocally connected brain areas...
September 15, 2017: Biological Psychiatry
https://www.readbyqxmd.com/read/28835530/rapid-visuomotor-feedback-gains-are-tuned-to-the-task-dynamics
#12
Sae Franklin, Daniel M Wolpert, David W Franklin
Adaptation to novel dynamics requires learning a motor memory, or a new pattern of predictive feedforward motor commands. Recently we demonstrated the up-regulation of rapid visuomotor feedback gains early in curl force field learning, which decrease once a predictive motor memory is learned. However, even after learning is complete, these feedback gains are higher than those observed in the null field trials. Interestingly these up-regulated feedback gains in the curl field were not observed in a constant force field...
August 23, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28833283/mir-337-3p-controls-hepatobiliary-gene-expression-and-transcriptional-dynamics-during-hepatic-cell-differentiation
#13
Céline Demarez, Claude Gérard, Sabine Cordi, Alexis Poncy, Younes Achouri, Nicolas Dauguet, David A Rosa, Patrick T Gunning, Isabelle Manfroid, Frédéric P Lemaigre
Transcriptional networks control the differentiation of the hepatocyte and cholangiocyte lineages from embryonic liver progenitor cells, and their subsequent maturation to the adult phenotype. However, how accurate levels of hepatocyte and cholangiocyte gene expression are determined during differentiation remains poorly understood. Here we identify miR-337-3p as a novel regulator of liver development. MiR-337-3p stimulates expression of cholangiocyte genes and represses hepatocyte genes in undifferentiated progenitor cells in vitro and in embryonic mouse livers...
August 17, 2017: Hepatology: Official Journal of the American Association for the Study of Liver Diseases
https://www.readbyqxmd.com/read/28813876/design-control-and-validation-of-the-variable-stiffness-exoskeleton-flexo
#14
Sariah Mghames, Marco Laghi, Cosimo Della Santina, Manolo Garabini, Manuel Catalano, Giorgio Grioli, Antonio Bicchi
In this paper we present the design of a one degree of freedom assistive platform to augment the strength of upper limbs. The core element is a variable stiffness actuator, closely reproducing the behavior of a pair of antagonistic muscles. The novelty introduced by this device is the analogy of its control parameters with those of the human muscle system, the threshold lengths. The analogy can be obtained from a proper tuning of the mechanical system parameters. Based on this, the idea is to control inputs by directly mapping the estimation of the muscle activations, e...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28808338/a-dynamical-framework-for-complex-fractional-killing
#15
Richard Ballweg, Andrew L Paek, Tongli Zhang
When chemotherapy drugs are applied to tumor cells with the same or similar genotypes, some cells are killed, while others survive. This fractional killing contributes to drug resistance in cancer. Through an incoherent feedforward loop, chemotherapy drugs not only activate p53 to induce cell death, but also promote the expression of apoptosis inhibitors which inhibit cell death. Consequently, cells in which p53 is activated early undergo apoptosis while cells in which p53 is activated late survive. The incoherent feedforward loop and the essential role of p53 activation timing makes fractional killing a complex dynamical challenge, which is hard to understand with intuition alone...
August 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28796509/predicting-thermal-behavior-of-secondary-organic-aerosols
#16
John H Offenberg, Michael Lewandowski, Tadeusz E Kleindienst, Kenneth S Docherty, Mohammed Jaoui, Jonathan Krug, Theran P Riedel, David A Olson
Volume concentrations of secondary organic aerosol (SOA) are measured in 139 steady-state, single precursor hydrocarbon oxidation experiments after passing through a temperature controlled inlet. The response to change in temperature is well predicted through a feedforward Artificial Neural Network. The most parsimonious model, as indicated by Akaike's Information Criterion, Corrected (AIC,C), utilizes 11 input variables, a single hidden layer of 4 tanh activation function nodes, and a single linear output function...
August 10, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28783639/supervised-learning-based-on-temporal-coding-in-spiking-neural-networks
#17
Hesham Mostafa
Gradient descent training techniques are remarkably successful in training analog-valued artificial neural networks (ANNs). Such training techniques, however, do not transfer easily to spiking networks due to the spike generation hard nonlinearity and the discrete nature of spike communication. We show that in a feedforward spiking network that uses a temporal coding scheme where information is encoded in spike times instead of spike rates, the network input-output relation is differentiable almost everywhere...
August 1, 2017: IEEE Transactions on Neural Networks and Learning Systems
https://www.readbyqxmd.com/read/28767379/composite-backstepping-consensus-algorithms-of-leader-follower-higher-order-nonlinear-multiagent-systems-subject-to-mismatched-disturbances
#18
Xiangyu Wang, Shihua Li, Michael Z Q Chen
This paper is devoted to solving the output consensus problem of leader-follower higher-order nonlinear multiagent systems subject to mismatched disturbances. The disturbances are allowed to be in higher-order forms. First, by constructing a generalized proportional-integral observer for each follower, estimates of the disturbances and their derivatives are obtained. At the same time, a distributed observer is also developed for the followers to estimate the leader state information. Second, based on the estimates of the disturbances and the leader state, together with the backstepping technique, a feedforward-feedback composite consensus control scheme is proposed...
July 27, 2017: IEEE Transactions on Cybernetics
https://www.readbyqxmd.com/read/28738310/postural-response-to-predictable-and-nonpredictable-visual-flow-in-children-and-adults
#19
Mark A Schmuckler
Children's (3-5years) and adults' postural reactions to different conditions of visual flow information varying in its frequency content was examined using a moving room apparatus. Both groups experienced four conditions of visual input: low-frequency (0.20Hz) visual oscillations, high-frequency (0.60Hz) oscillations, multifrequency nonpredictable visual input, and no imposed visual information. Analyses of the frequency content of anterior-posterior (AP) sway revealed that postural reactions to the single-frequency conditions replicated previous findings; children were responsive to low- and high-frequency oscillations, whereas adults were responsive to low-frequency information...
November 2017: Journal of Experimental Child Psychology
https://www.readbyqxmd.com/read/28736520/combined-effects-of-feedforward-inhibition-and-excitation-in-thalamocortical-circuit-on-the-transitions-of-epileptic-seizures
#20
Denggui Fan, Lixia Duan, Qian Wang, Guoming Luan
The mechanisms underlying electrophysiologically observed two-way transitions between absence and tonic-clonic epileptic seizures in cerebral cortex remain unknown. The interplay within thalamocortical network is believed to give rise to these epileptic multiple modes of activity and transitions between them. In particular, it is thought that in some areas of cortex there exists feedforward inhibition from specific relay nucleus of thalamus (TC) to inhibitory neuronal population (IN) which has even more stronger functions on cortical activities than the known feedforward excitation from TC to excitatory neuronal population (EX)...
2017: Frontiers in Computational Neuroscience
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