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feedforward control

Yasunobu Murata, Matthew T Colonnese
Spontaneous retinal waves are critical for the development of receptive fields in visual thalamus (LGN) and cortex (VC). Despite a detailed understanding of the circuit specializations in retina that generate waves, whether central circuit specializations also exist to control their propagation through visual pathways of the brain is unknown. Here we identify a developmentally transient, corticothalamic amplification of retinal drive to thalamus as a mechanism for retinal wave transmission in the infant rat brain...
October 11, 2016: ELife
Shahin Nasr, Herminia D Rosas
: The caudate nucleus is a part of the visual corticostriatal loop (VCSL), receiving input from different visual areas and projecting back to the same cortical areas via globus pallidus, substantia nigra, and thalamus. Despite perceptual and navigation impairments in patients with VCSL disruption due to caudate atrophy (e.g., Huntington's disease, HD), the relevance of the caudate nucleus and VCSL on cortical visual processing is not fully understood. In a series of fMRI experiments, we found that the caudate showed a stronger functional connection to parahippocampal place area (PPA) compared with adjacent regions (e...
October 5, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Elisa Albini, Verdiana Rosini, Marco Gargaro, Giada Mondanelli, Maria L Belladonna, Maria Teresa Pallotta, Claudia Volpi, Francesca Fallarino, Antonio Macchiarulo, Cinzia Antognelli, Roberta Bianchi, Carmine Vacca, Paolo Puccetti, Ursula Grohmann, Ciriana Orabona
The enzyme indoleamine 2,3-dioxygenase 1 (IDO1) catalyses the initial, rate-limiting step in tryptophan (Trp) degradation, resulting in tryptophan starvation and the production of immunoregulatory kynurenines. IDO1's catalytic function has long been considered as the one mechanism responsible for IDO1-dependent immune suppression by dendritic cells (DCs), which are master regulators of the balance between immunity and tolerance. However, IDO1 also harbours immunoreceptor tyrosine-based inhibitory motifs, (ITIM1 and ITIM2), that, once phosphorylated, bind protein tyrosine phosphatases, (SHP-1 and SHP-2), and thus trigger an immunoregulatory signalling in DCs...
September 30, 2016: Journal of Cellular and Molecular Medicine
Adina E Draghici, J Andrew Taylor
Cardiovascular variabilities were recognized over 250 years ago, but only in the past 20 years has their apparent utility come to be appreciated. Technological advancement has allowed precise measurement and quantification of short-term cardiovascular fluctuations; however, our understanding of the integrated mechanisms which underlie these oscillations is inadequate for their widespread application. Both autonomic branches, the parasympathetic and sympathetic nervous system, are key determinants of the magnitude of these spontaneous cardiovascular fluctuations...
September 28, 2016: Journal of Physiological Anthropology
Rinaldo David D'Souza, Andrew Max Meier, Pawan Bista, Quanxin Wang, Andreas Burkhalter
Diverse features of sensory stimuli are selectively processed in distinct brain areas. The relative recruitment of inhibitory and excitatory neurons within an area controls the gain of neurons for appropriate stimulus coding. We examined how such a balance of inhibition and excitation is differentially recruited across multiple levels of a cortical hierarchy by mapping the locations and strengths of synaptic inputs to pyramidal and parvalbumin (PV)-expressing neurons in feedforward and feedback pathways interconnecting primary (V1) and two higher visual areas...
September 26, 2016: ELife
Frank M Drop, Daan M Pool, Marinus M van Paassen, Max Mulder, Heinrich H Bulthoff
Realistic manual control tasks typically involve predictable target signals and random disturbances. The human controller (HC) is hypothesized to use a feedforward control strategy for target-following, in addition to feedback control for disturbance-rejection. Little is known about human feedforward control, partly because common system identification methods have difficulty in identifying whether, and (if so) how, the HC applies a feedforward strategy. In this paper, an identification procedure is presented that aims at an objective model selection for identifying the human feedforward response, using linear time-invariant autoregressive with exogenous input models...
September 19, 2016: IEEE Transactions on Cybernetics
Li Xu, Hao Ren, Guangang Gao, Linkang Zhou, Muhammad Arshad Malik, Peng Li
Metabolism refers to a chain of chemical reactions converting food/fuel into energy to conduct cellular processes, including the synthesis of the building blocks of the body, such as proteins, lipids, nucleic acids, and carbohydrates, and the elimination of nitrogenous wastes. Metabolic chain reactions are catalyzed by various enzymes that are orchestrated in specific pathways. Metabolic pathways are important for organisms to grow and reproduce, maintain their structures, and respond to their environments...
September 20, 2016: IUBMB Life
Shawn M O'Connor, Jeremy D Wong, J Maxwell Donelan
While forcing of end-tidal gases by regulating inspired gas concentrations is a common technique for studying cardio-respiratory physiology, independently controlling end-tidal gases is technically challenging. Feedforward control methods are challenging because end-tidal values vary as a dynamic function of both inspired gases and other non-regulated physiological parameters. Conventional feedback control is limited by delays within the lungs and body tissues, and within the end-tidal forcing system itself...
September 15, 2016: Journal of Applied Physiology
Terry Elliott
Integrate-and-express models of synaptic plasticity propose that synapses integrate plasticity induction signals before expressing synaptic plasticity. By discerning trends in their induction signals, synapses can control destabilizing fluctuations in synaptic strength. In a feedforward perceptron framework with binary-strength synapses for associative memory storage, we have previously shown that such a filter-based model outperforms other, nonintegrative, "cascade"-type models of memory storage in most regions of biologically relevant parameter space...
September 14, 2016: Neural Computation
Gauravkumar K Patel, Strahinja Dosen, Claudio Castellini, Dario Farina
OBJECTIVE: Closing the loop in myoelectric prostheses by providing artificial somatosensory feedback to the user is an important need for prosthetic users. Previous studies investigated feedback strategies in combination with the control of one degree of freedom of simple grippers. Modern hands, however, are sophisticated multifunction systems. In this study, we assessed multichannel electrotactile feedback integrated with an advanced method for the simultaneous and proportional control of individual fingers of a dexterous hand...
October 2016: Journal of Neural Engineering
Laura M McGarry, Adam G Carter
UNLABELLED: Interactions between the prefrontal cortex (PFC) and basolateral amygdala (BLA) regulate emotional behaviors. However, a circuit-level understanding of functional connections between these brain regions remains incomplete. The BLA sends prominent glutamatergic projections to the PFC, but the overall influence of these inputs is predominantly inhibitory. Here we combine targeted recordings and optogenetics to examine the synaptic underpinnings of this inhibition in the mouse infralimbic PFC...
September 7, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Evie van der Spoel, Steffy W Jansen, Abimbola A Akintola, Bart E Ballieux, Christa M Cobbaert, P Eline Slagboom, Gerard Jan Blauw, Rudi G J Westendorp, Hanno Pijl, Ferdinand Roelfsema, Diana van Heemst
Reduced growth hormone (GH) signaling has been consistently associated with increased health and lifespan in various mouse models. Here, we assessed GH secretion and its control in relation with human familial longevity. We frequently sampled blood over 24 h in 19 middle-aged offspring of long-living families from the Leiden Longevity Study together with 18 of their partners as controls. Circulating GH concentrations were measured every 10 min and insulin-like growth factor 1 (IGF-1) and insulin-like growth factor binding protein 3 (IGFBP3) every 4 h...
September 7, 2016: Aging Cell
Katalin Gemes, Yu Jung Kim, Ky Young Park, Panagiotis Nikolaou Moschou, Efthimios Andronis, Chryssanthi Valassakis, Andreas Roussis, Kalliopi A Roubelakis-Angelakis
Reactive Oxygen Species (ROS) generating and scavenging pathways balance ROS levels. The intracellular NADPH-oxidase is considered as the primary ROS-generating source in cells. Recently, the apoplastic polyamine (PA) oxidase (PAO) emerged as a significant ROS source in plants. The apoplastic PAO catalyzes the oxidation of the higher PAs, spermidine (Spd) and spermine (Spm), and is considered as a secondary ROS-generating source. Here we unravel a feedback loop that controls ROS burst under salinity and includes NADPH-oxidase and PAO...
September 6, 2016: Plant Physiology
Cédrick T Bonnet, Stéphane Baudry
In everyday life, individuals sometimes have to perform precise, or challenging, visual tasks in upright standing. Upright, one problem to perform precise saccades and fixations is that the body oscillates continuously in a mainly unpredictable way. Current cognitive models assume that the central nervous system should divide its attention to perform these 'dual tasks' because of limited attentional resources (keeping balance and performing the precise visual task). The problem with the concept of duality is that individuals (need to) succeed in precise visual tasks upright and should not be more unstable and inefficient - because of a division of attention - in these tasks...
August 30, 2016: Gait & Posture
Eva-Maria Reuter, Ross Cunnington, Jason Brett Mattingley, Stephan Riek, Timothy John Carroll
There are well-documented differences in the way that people typically perform identical motor tasks with their dominant and the non-dominant arms. According Yadav and Sainburg's (2011) hybrid-control model, this is because the two arms rely to different degrees on impedance control versus predictive control processes. Here we assessed whether differences in limb control mechanisms influence the rate of feedforward compensation to a novel dynamic environment. Seventy-five healthy, right-handed participants, divided into four subsamples depending on the arm (left, right) and direction of the force field (ipsilateral, contralateral), reached to central targets in velocity-dependent curl force-fields...
August 31, 2016: Journal of Neurophysiology
Jhih-Hong Lin, Mao-Hsiung Chiang
Magnetic shape memory (MSM) alloys are a new class of smart materials with extraordinary strains up to 12% and frequencies in the range of 1 to 2 kHz. The MSM actuator is a potential device which can achieve high performance electromagnetic actuation by using the properties of MSM alloys. However, significant non-linear hysteresis behavior is a significant barrier to control the MSM actuator. In this paper, the Preisach model was used, by capturing experiments from different input signals and output responses, to model the hysteresis of MSM actuator, and the inverse Preisach model, as a feedforward control, provided compensational signals to the MSM actuator to linearize the hysteresis non-linearity...
2016: Sensors
Shunta Togo, Hiroshi Imamizu
We grasp and dexterously manipulate an object through multi-digit synergy. In the framework of the uncontrolled manifold (UCM) hypothesis, multi-digit synergy is defined as the coordinated control mechanism of fingers to stabilize variable important for task success, e.g., total force. Previous studies reported anticipatory synergy adjustments (ASAs) that correspond to a drop of the synergy index before a quick change of the total force. The present study compared ASA's properties with individual performances of feedforward force control to investigate a relationship of those...
October 6, 2016: Neuroscience Letters
Seong Ik Han, Jangmyung Lee
This paper presents finite-time sliding mode control (FSMC) with predefined constraints for the tracking error and sliding surface in order to obtain robust positioning of a robot manipulator with input nonlinearity due to an unknown deadzone and external disturbance. An assumed model feedforward FSMC was designed to avoid tedious identification procedures for the manipulator parameters and to obtain a fast response time. Two constraint switching control functions based on the tracking error and finite-time sliding surface were added to the FSMC to guarantee the predefined tracking performance despite the presence of an unknown deadzone and disturbance...
August 16, 2016: ISA Transactions
Liyang Xiong, Wenjia Shi, Chao Tang
Adaptation is a ubiquitous feature in biological sensory and signaling networks. It has been suggested that adaptive systems may follow certain simple design principles across diverse organisms, cells and pathways. One class of networks that can achieve adaptation utilizes an incoherent feedforward control, in which two parallel signaling branches exert opposite but proportional effects on the output at steady state. In this paper, we generalize this adaptation mechanism by establishing a steady-state proportionality relationship among a subset of nodes in a network...
2016: Physical Biology
Nora Rauch, Oleksii S Rukhlenko, Walter Kolch, Boris N Kholodenko
The RAS/RAF/MEK/MAPK kinase pathway has been extensively studied for more than 25 years, yet we continue to be puzzled by its intricate dynamic control and plasticity. Different spatiotemporal MAPK dynamics bring about distinct cell fate decisions in normal vs cancer cells and developing organisms. Recent modelling and experimental studies provided novel insights in the versatile MAPK dynamics concerted by a plethora of feedforward/feedback regulations and crosstalk on multiple timescales. Multiple cancer types and various developmental disorders arise from persistent alterations of the MAPK dynamics caused by RAS/RAF/MEK mutations...
August 10, 2016: Current Opinion in Structural Biology
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