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1
Rungta, Satya, Debaleena Basu, Naveen Sendhilnathan i Aditya Murthy. "Preparatory activity links the frontal eye field response with small amplitude motor unit recruitment of neck muscles during gaze planning". Journal of Neurophysiology 126, nr 2 (1.08.2021): 451–63. http://dx.doi.org/10.1152/jn.00141.2021.
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This study shows that the temporal aspects of a motor plan in the oculomotor circuitry can be accessed by peripheral neck muscles hundreds of milliseconds before the instruction to initiate a saccadic eye movement. The coupling between central and peripheral processes during the delay time is mediated by the recruitment pattern of motor units with smaller amplitude. These findings suggest that information processed in cortical areas could be read from periphery before execution.
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Ackerley, Rochelle, Michael Borich, Calogero Maria Oddo i Silvio Ionta. "Insights and Perspectives on Sensory-Motor Integration and Rehabilitation". Multisensory Research 29, nr 6-7 (2016): 607–33. http://dx.doi.org/10.1163/22134808-00002530.
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The present review focuses on the flow and interaction of somatosensory-motor signals in the central and peripheral nervous system. Specifically, where incoming sensory signals from the periphery are processed and interpreted to initiate behaviors, and how ongoing behaviors produce sensory consequences encoded and used to fine-tune subsequent actions. We describe the structure–function relations of this loop, how these relations can be modeled and aspects of somatosensory-motor rehabilitation. The work reviewed here shows that it is imperative to understand the fundamental mechanisms of the somatosensory-motor system to restore accurate motor abilities and appropriate somatosensory feedback. Knowledge of the salient neural mechanisms of sensory-motor integration has begun to generate innovative approaches to improve rehabilitation training following neurological impairments such as stroke. The present work supports the integration of basic science principles of sensory-motor integration into rehabilitation procedures to create new solutions for sensory-motor disorders.
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Suminski, Aaron J., Philip Mardoum, Timothy P. Lillicrap i Nicholas G. Hatsopoulos. "Temporal evolution of both premotor and motor cortical tuning properties reflect changes in limb biomechanics". Journal of Neurophysiology 113, nr 7 (kwiecień 2015): 2812–23. http://dx.doi.org/10.1152/jn.00486.2014.
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A prevailing theory in the cortical control of limb movement posits that premotor cortex initiates a high-level motor plan that is transformed by the primary motor cortex (MI) into a low-level motor command to be executed. This theory implies that the premotor cortex is shielded from the motor periphery, and therefore, its activity should not represent the low-level features of movement. Contrary to this theory, we show that both dorsal (PMd) and ventral premotor (PMv) cortexes exhibit population-level tuning properties that reflect the biomechanical properties of the periphery similar to those observed in M1. We recorded single-unit activity from M1, PMd, and PMv and characterized their tuning properties while six rhesus macaques performed a reaching task in the horizontal plane. Each area exhibited a bimodal distribution of preferred directions during execution consistent with the known biomechanical anisotropies of the muscles and limb segments. Moreover, these distributions varied in orientation or shape from planning to execution. A network model shows that such population dynamics are linked to a change in biomechanics of the limb as the monkey begins to move, specifically to the state-dependent properties of muscles. We suggest that, like M1, neural populations in PMd and PMv are more directly linked with the motor periphery than previously thought.
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Brezina, Vladimir, Charles C. Horn i Klaudiusz R. Weiss. "Modeling Neuromuscular Modulation in Aplysia. III. Interaction of Central Motor Commands and Peripheral Modulatory State for Optimal Behavior". Journal of Neurophysiology 93, nr 3 (marzec 2005): 1523–56. http://dx.doi.org/10.1152/jn.00475.2004.
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Recent work in computational neuroethology has emphasized that “the brain has a body”: successful adaptive behavior is not simply commanded by the nervous system, but emerges from interactions of nervous system, body, and environment. Here we continue our study of these issues in the accessory radula closer (ARC) neuromuscular system of Aplysia. The ARC muscle participates in the animal's feeding behaviors, a set of cyclical, rhythmic behaviors driven by a central pattern generator (CPG). Patterned firing of the ARC muscle's two motor neurons, B15 and B16, releases not only ACh to elicit the muscle's contractions but also peptide neuromodulators that then shape the contractions through a complex network of actions on the muscle. These actions are dynamically complex: some are fast, but some are slow, so that they are temporally uncoupled from the motor neuron firing pattern in the current cycle. Under these circumstances, how can the nervous system, through just the narrow channel of the firing patterns of the motor neurons, control the contractions, movements, and behavior in the periphery? In two earlier papers, we developed a realistic mathematical model of the B15/B16-ARC neuromuscular system and its modulation. Here we use this model to study the functional performance of the system in a realistic behavioral task. We run the model with two kinds of inputs: a simple set of regular motor neuron firing patterns that allows us to examine the entire space of patterns, and the real firing patterns of B15 and B16 previously recorded in a 21/2-h-long meal of 749 cycles in an intact feeding animal. These real patterns are extremely irregular. Our main conclusions are the following. 1) The modulation in the periphery is necessary for superior functional performance. 2) The components of the modulatory network interact in nonlinear, context- and task-dependent combinations for best performance overall, although not necessarily in any particular cycle. 3) Both the fast and the slow dynamics of the modulatory state make important contributions. 4) The nervous system controls different components of the periphery to different degrees. To some extent the periphery operates semiautonomously. However, the structure of the peripheral modulatory network ensures robust performance under all circumstances, even with the irregular motor neuron firing patterns and even when the parameters of the functional task are randomly varied from cycle to cycle to simulate a variable feeding environment. In the variable environment, regular firing patterns, which are fine-tuned to one particular task, fail to provide robust performance. We propose that the CPG generates the irregular firing patterns, which nevertheless are guaranteed to give robust performance overall through the actions of the peripheral modulatory network, as part of a trial-and-error feeding strategy in a variable, uncertain environment.
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van der Mars, Hans, Paul Darst, Bill Vogler i Barbara Cusimano. "Active Supervision Patterns of Physical Education Teachers and Their Relationship with Student Behaviors". Journal of Teaching in Physical Education 14, nr 1 (październik 1994): 99–112. http://dx.doi.org/10.1123/jtpe.14.1.99.
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Supervision patterns of elementary physical educators were analyzed in relation to work involvement patterns of students in each teacher’s class. The supervision patterns analyzed included teacher location, rate of movement, and provision of verbal feedback. Work involvement by students was categorized into on-task, off-task, total motor engagement, and successful motor engagement (ALT-PE). Results showed that teachers spent more time along the periphery of the activity area, and that they were positioned more along the sides. They were active movers, averaging six sector changes per minute, and active in providing verbal feedback (3.2/min). Teacher feedback patterns did not correlate with teacher location/movement patterns. Teachers’ location (periphery) and movement correlated significantly with students’ total motor engagement. Teacher movement also correlated significantly with ALT-PE. Positive behavior feedback correlated with students’ on-task behaviors. Findings indicate that active supervision is important in maintaining students’ involvement with learning tasks in physical education.
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Sun, Jing Rui, i Jin Cheng Wu. "Research and Implementation of Folding Machine Control System Based on MPU". Advanced Materials Research 383-390 (listopad 2011): 5838–43. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.5838.
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The purpose of this paper is to analyze the working principle of folding machine and it also explains the working mode of the stepper motor. Basing on these, the control-system of folding machine is designed. It is through the AT89C52 MPU and the corresponding circuit of periphery to control the two stepper motors. So it can drive the feeding roller and the paper roller to overlay in accordance with the predefined size. The system achieves the automation of folding. It not only reduces the labor, but also improves the efficiency and accuracy of folding. It has a very broad application prospect.
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Ebneth, A., R. Godemann, K. Stamer, S. Illenberger, B. Trinczek, E. M. Mandelkow i E. Mandelkow. "Overexpression of Tau Protein Inhibits Kinesin-dependent Trafficking of Vesicles, Mitochondria, and Endoplasmic Reticulum: Implications for Alzheimer's Disease". Journal of Cell Biology 143, nr 3 (2.11.1998): 777–94. http://dx.doi.org/10.1083/jcb.143.3.777.
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The neuronal microtubule-associated protein tau plays an important role in establishing cell polarity by stabilizing axonal microtubules that serve as tracks for motor-protein–driven transport processes. To investigate the role of tau in intracellular transport, we studied the effects of tau expression in stably transfected CHO cells and differentiated neuroblastoma N2a cells. Tau causes a change in cell shape, retards cell growth, and dramatically alters the distribution of various organelles, known to be transported via microtubule-dependent motor proteins. Mitochondria fail to be transported to peripheral cell compartments and cluster in the vicinity of the microtubule-organizing center. The endoplasmic reticulum becomes less dense and no longer extends to the cell periphery. In differentiated N2a cells, the overexpression of tau leads to the disappearance of mitochondria from the neurites. These effects are caused by tau's binding to microtubules and slowing down intracellular transport by preferential impairment of plus-end–directed transport mediated by kinesin-like motor proteins. Since in Alzheimer's disease tau protein is elevated and mislocalized, these observations point to a possible cause for the gradual degeneration of neurons.
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García-Crescioni, Keyla, Timothy J. Fort, Estee Stern, Vladimir Brezina i Mark W. Miller. "Feedback From Peripheral Musculature to Central Pattern Generator in the Neurogenic Heart of the Crab Callinectes sapidus: Role of Mechanosensitive Dendrites". Journal of Neurophysiology 103, nr 1 (styczeń 2010): 83–96. http://dx.doi.org/10.1152/jn.00561.2009.
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The neurogenic heart of decapod crustaceans is a very simple, self-contained, model central pattern generator (CPG)-effector system. The CPG, the nine-neuron cardiac ganglion (CG), is embedded in the myocardium itself; it generates bursts of spikes that are transmitted by the CG's five motor neurons to the periphery of the system, the myocardium, to produce its contractions. Considerable evidence suggests that a CPG-peripheral loop is completed by a return feedback pathway through which the contractions modify, in turn, the CG motor pattern. One likely pathway is provided by dendrites, presumably mechanosensitive, that the CG neurons project into the adjacent myocardial muscle. Here we have tested the role of this pathway in the heart of the blue crab, Callinectes sapidus . We performed “de-efferentation” experiments in which we cut the motor neuron axons to the myocardium and “de-afferentation” experiments in which we cut or ligated the dendrites. In the isolated CG, these manipulations had no effect on the CG motor pattern. When the CG remained embedded in the myocardium, however, these manipulations, interrupting either the efferent or afferent limb of the CPG-peripheral loop, decreased contraction amplitude, increased the frequency of the CG motor neuron spike bursts, and decreased the number of spikes per burst and burst duration. Finally, passive stretches of the myocardium likewise modulated the spike bursts, an effect that disappeared when the dendrites were cut. We conclude that feedback through the dendrites indeed operates in this system and suggest that it completes a loop through which the system self-regulates its activity.
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Krzyszton, C. P., N. L. Sparkman, R. W. Grant, J. B. Buchanan, S. R. Broussard, J. Woods i R. W. Johnson. "Exacerbated fatigue and motor deficits in interleukin-10-deficient mice after peripheral immune stimulation". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 295, nr 4 (październik 2008): R1109—R1114. http://dx.doi.org/10.1152/ajpregu.90302.2008.
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The anti-inflammatory cytokine interleukin (IL)-10 is important for regulating inflammation in the periphery and brain, but whether it protects against infection- or age-related psychomotor disturbances and fatigue is unknown. Therefore, the present study evaluated motor coordination, time to fatigue, and several central and peripheral proinflammatory cytokines in male young adult (3-mo-old) and middle-aged (12-mo-old) wild-type (IL-10+/+) and IL-10-deficient (IL-10−/−) mice after intraperitoneal injection of lipopolysaccharide (LPS) or saline. No age-related differences were observed; therefore, data from the two ages were pooled and analyzed to determine effects of genotype and treatment. LPS treatment increased IL-1β, IL-6, and TNFα mRNA in all brain areas examined in IL-10+/+and IL-10−/−mice, but to a greater extent and for a longer time in IL-10−/−mice. Plasma IL-1β and IL-6 were increased similarly in IL-10+/+and IL-10−/−mice 4 h after LPS but remained elevated longer in IL-10−/−mice, whereas TNFα was higher in IL-10−/−mice throughout after LPS treatment. Motor performance and motor learning in IL-10+/+mice were not affected by LPS treatment; however, both were reduced in IL-10−/−mice treated with LPS compared with those treated with saline. Furthermore, although LPS reduced the time to fatigue in IL-10+/+and IL-10−/−mice, the effects were exacerbated in IL-10−/−mice. Thus the increased brain and peripheral inflammation induced by LPS in IL-10−/−mice was associated with increased coordination deficits and fatigue. These data suggest that IL-10 may inhibit motor deficits and fatigue associated with peripheral infections via its anti-inflammatory effects.
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Gu, C., D. K. Wood, P. L. Gribble i B. D. Corneil. "A Trial-by-Trial Window into Sensorimotor Transformations in the Human Motor Periphery". Journal of Neuroscience 36, nr 31 (3.08.2016): 8273–82. http://dx.doi.org/10.1523/jneurosci.0899-16.2016.
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Fort, Timothy J., Vladimir Brezina i Mark W. Miller. "Modulation of an Integrated Central Pattern Generator–Effector System: Dopaminergic Regulation of Cardiac Activity in the Blue Crab Callinectes sapidus". Journal of Neurophysiology 92, nr 6 (grudzień 2004): 3455–70. http://dx.doi.org/10.1152/jn.00550.2004.
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Theoretical studies have suggested that the output of a central pattern generator (CPG) must be matched to the properties of its peripheral effector system to ensure production of functional behavior. One way that such matching could be achieved is through coordinated central and peripheral modulation. In this study, morphological and physiological methods were used to examine the sources and actions of dopaminergic modulation in the cardiac system of the blue crab, Callinectes sapidus. Immunohistochemical localization of tyrosine hydroxylase (TH) revealed a prominent neuron in the commissural ganglion, the L-cell, that projected a large-diameter axon to the pericardial organ (PO) by an indirect and circuitous route. Within the PO, the L-cell axon gave rise to fine varicose fibers, suggesting that it releases dopamine in a neurohormonal fashion onto the heart musculature. In addition, one branch of the axon continued beyond the PO to the heart, where it innervated the anterior motor neurons and the posterior pacemaker region of the cardiac ganglion (CG). In physiological experiments, exogenous dopamine produced multiple effects on contraction and motor neuron burst parameters that corresponded to the dual central-peripheral modulation suggested by the L-cell morphology. Interestingly, parameters of the ganglionic motor output were modulated differently in the isolated CG and in a novel semi-intact system where the CG remained embedded within the heart musculature. These observations suggest a critical role of feedback from the periphery to the CG and underscore the requirement for integration of peripheral (neurohormonal) actions and direct ganglionic modulation in the regulation of this exceptionally simple system.
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Westerfield, M. "Substrate interactions affecting motor growth cone guidance during development and regeneration". Journal of Experimental Biology 132, nr 1 (1.09.1987): 161–75. http://dx.doi.org/10.1242/jeb.132.1.161.
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Most serious injuries of spinal nerves or roots in man and other higher vertebrates lead to permanent loss of control of skeletal muscles. In some cases this may be due to a failure of motor axons to regenerate, although even when functional neuromuscular connections are re-established, coordinated use of body and limb muscles may be absent. In both mammals and lower vertebrates, damaged motor axons usually regrow and reform functional connections with muscles, although these connections are often inappropriate. The selectivity of reinnervation is improved by maintaining alignment of the severed ends of the nerve. Thus, factors operating near the lesion site may direct regenerating motor axons into fascicles in the distal nerve stump that lead to inappropriate muscles. The identity of some of these factors is suggested by recent studies of developing systems which have shown that motor axons are directed in their growth. (a) The filopodia of their growth cones sample a limited region of the periphery. If motor growth cones extend too far from their normal pathways they establish connections with inappropriate muscles. (b) Motor growth cones normally extend into regions of embryos rich in the extracellular matrix molecule laminin, and avoid regions containing fibronectin. Moreover, motor growth cones extend on laminin but not on fibronectin substrates in vitro. In peripheral nerves, these two molecules are differentially distributed; laminin is expressed by Schwann cells in the endoneurium whereas fibronectin is expressed by fibroblasts primarily in the perineurium. These studies suggest that regenerating motor growth cones may be directed to appropriate muscles if their original fascicles within the distal nerve stump are within filopodial reach but may not be able to escape the fibronectin-rich perineurial sheath once directed into an inappropriate fascicle.
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Barer, A. S., K. A. Semeneva, V. I. Dotsenko, V. M. Sinigin, E. G. Sologtlbov, E. P. Tikhomirov i O. G. Sheinkman. "New possibilities of rehabilitation of the disordered motor and speech functions in patients with paralyses of the cerebral origin". Neurology Bulletin XXVI, nr 1-2 (20.04.1994): 26–31. http://dx.doi.org/10.17816/nb107009.
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The theoretical justification of the new rehabilitation method of the disordered motor and speech functions of patients with paralyses of the cerebral origin is given. The method provided is based on the formation (recovery) of new functional connections at the expense of the afferentation from periphery and improvement of tissue trophicity being under load.
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Sirotkina, Irina. "From Top-Down Control to Self-Organisation: The “Thaw” and Motor Action Theory". Philosophical Literary Journal Logos 30, nr 2 (2020): 129–56. http://dx.doi.org/10.22394/0869-5377-2020-2-129-152.
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The period from the late 1950s to the mid-1960s in the Soviet Union was known as the “Thaw,” a political era that fostered hopes of restoring the rule of law and democracy to the country. In that period cybernetics came to symbolize both scientific progress and social change. The Soviet intelligentsia had survived the hardship of Stalinist repression and now regarded the new discipline, which brought together the natural sciences and the human sciences, as a pathway to building a freer and more equal society. After decades of domination by Pavlovian doctrine, a paradigm shift was under way in physiology and psychology. Cybernetics reinforced the new paradigm, which put forward ideas of purposive behavior and self-organization in living and non-living systems. The conditioned reflex and a simplistic one-to-one view of connections in the nervous system gave way to more sophisticated and complex models, which could be formalized mathematically. Previous models of control in living organisms were mostly hierarchical and included top-down control of peripheral movement by the motor centers. The new models supplemented this picture with feedback commands from the periphery to the center. By the time cybernetics had made its appearance in the Soviet Union, new models of control had already been formulated in physiology by Nikolay Bernstein (1896– 1966). He termed the feedback from afferent signals “sensorial corrections,” meaning that they play an important part in adapting central control to the changing situation at the periphery of movement. The new paradigm emphasized horizontal connections over vertical ones, and new models took hold based on less “totalitarian” and more “democratic” principles, such as the idea of automatic or autonomous functioning of intermediate centers, the mathematical concept of well-organized functions, the theory of “the collective behavior of automata,” etc. This line of research was carried out in the USSR as well as abroad by Bernstein’s students and followers who formed the Moscow School of Motor Control. The author argues that this preference for less hierarchical models was one expression of the Thaw’s trend toward liberalization of life within the USSR and greater involvement in international politics.
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Sink, H., i P. M. Whitington. "Pathfinding in the central nervous system and periphery by identified embryonic Drosophila motor axons". Development 112, nr 1 (1.05.1991): 307–16. http://dx.doi.org/10.1242/dev.112.1.307.
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We have studied the pattern of axon outgrowth from the identified embryonic Drosophila motorneurons, RP1, RP3, RP4 and RP5, from the onset of axonogenesis to the time of arborization over target muscles. Lucifer Yellow was intracellularly injected into each of these neurons to obtain a detailed description of the morphology of their growth cones and of the pathways that they follow. We have divided the sequence of axon growth from these neurons into five major phases. In the first phase, the growth cone of each RP axon grows medially along its contralateral homologue along the anterior commissure. Each RP axon follows a separate path across the midline in the anterior commissure. After crossing the ventral midline, the axons wrap around specific contralateral RP somata. In the second phase, each axon grows posteriorly and dorsally down the contralateral longitudinal connective, fasciculating with the other RP axons. In the third phase, the axons turn into the intersegmental nerve via the anterior nerve root, then cross over to the segmental nerve, before contacting the external surfaces of intermediate muscles 15/16. They do not fasciculate with the pioneering aCC and RP2 axons at this time. In the fourth phase, the axons advance laterally across the ventral muscle group. During this phase, each axon extends processes over a number of inappropriate muscles as well as contacting its correct, target muscle. In the final phase, the processes to inappropriate muscles are withdrawn, generating the mature pattern of motor axon projections. There is no consistent, clear difference between the RP motorneurons in the relative timing of axon outgrowth.
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Gomi, H., N. Abekawa i S. Shimojo. "The Hand Sees Visual Periphery Better Than the Eye: Motor-Dependent Visual Motion Analyses". Journal of Neuroscience 33, nr 42 (16.10.2013): 16502–9. http://dx.doi.org/10.1523/jneurosci.4741-12.2013.
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Adler, Henry J., Inna A. Belyantseva, Raymond C. Merritt, Gregory I. Frolenkov, Gerard W. Dougherty i Bechara Kachar. "Expression of prestin, a membrane motor protein, in the mammalian auditory and vestibular periphery". Hearing Research 184, nr 1-2 (październik 2003): 27–40. http://dx.doi.org/10.1016/s0378-5955(03)00192-8.
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Zeller, Jörg, Valerie Schneider, Saniniuj Malayaman, Shin-ichi Higashijima, Hitoshi Okamoto, Jianfang Gui, Shuo Lin i Michael Granato. "Migration of Zebrafish Spinal Motor Nerves into the Periphery Requires Multiple Myotome-Derived Cues". Developmental Biology 252, nr 2 (grudzień 2002): 241–56. http://dx.doi.org/10.1006/dbio.2002.0852.
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Hu, Ling Yin. "Research on Design of BLDCM Controlling System Based on FPGA". Applied Mechanics and Materials 687-691 (listopad 2014): 3120–23. http://dx.doi.org/10.4028/www.scientific.net/amm.687-691.3120.
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Brushless dc motor is widely used in high electric field because of its simple structure, large power density, excellent speed regulating performance, and low noise characteristics. This paper describes a brushless DC motor real-time control system based on FPGA. The DC motor is controlled by PWM model and control model which simple the circuit; Calculating the rate of motor by determining the impulse width of n. hall sensor signal; Adopting the soft-core processor embedded in FPGA process increment PID arithmetic control, improve the system real time performance. Experimental results show that the hardware and software are reasonable, owning very good reliability and real time performance. The control system's hardware circuit was designed and implemented such as FPGA periphery circuit, drive circuit, current detecting circuit and so on. And the control arithmetic of current loop, position loop and speed loop were designed and the closed loop control of control system in hardware was achieved.
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Shi, Min, Allison R. Jones, Mark S. Niedringhaus, Rebecca J. Pearson, Ann M. Biehl, Manuel Ferreira, Niaz Sahibzada, Joseph G. Verbalis i Richard A. Gillis. "Glucose acts in the CNS to regulate gastric motility during hypoglycemia". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 285, nr 5 (listopad 2003): R1192—R1202. http://dx.doi.org/10.1152/ajpregu.00179.2003.
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Our purposes were to 1) develop an animal model where intravenously (iv) administered d-glucose consistently inhibited antral motility, and 2) use this model to assess whether iv glucose acts to inhibit motility from a peripheral or a central nervous system site and to elucidate the factor(s) that determine(s) whether stomach motor function is sensitive to changes in blood glucose. Rats were anesthetized with α-chloralose-urethane, and antral motility was measured by a strain-gauge force transducer sutured to the antrum. In some cases, antral motility and gastric tone were measured by monitoring intragastric balloon pressure. Increases in blood glucose were produced by continuous iv infusion of 25% d-glucose at 2 ml/h. Inhibition of antral motility and gastric tone was observed when gastric contractions were induced by hypoglycemia (subcutaneously administered insulin, 2.5 IU/animal). In contrast, no inhibition of gastric motor function was observed when glucose infusion was tested on gastric contractions that were 1) spontaneously occurring, 2) evoked by iv administered bethanechol in vagotomized animals, and 3) evoked by the TRH analog RX77368, microinjected into the dorsal motor nucleus of the vagus. Using the model of insulin-induced hypoglycemia to increase gastric motor activity, we found that neither sectioning the hepatic branch of the vagus ( n = 5), nor treating animals with capsaicin to destroy sensory vagal afferent nerves ( n = 5) affected the ability of iv d-glucose to inhibit gastric motor function. Our results indicate that an important factor determining whether stomach motor function will be sensitive to changes in blood glucose is the method used to stimulate gastric contractions, and that the primary site of the inhibitory action of iv glucose on gastric motility is the central nervous system rather than the periphery.
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Zeller, J., i M. Granato. "The zebrafish diwanka gene controls an early step of motor growth cone migration". Development 126, nr 15 (1.08.1999): 3461–72. http://dx.doi.org/10.1242/dev.126.15.3461.
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During vertebrate embryogenesis different classes of motor axons exit the spinal cord and migrate on common axonal paths into the periphery. Surprisingly little is known about how this initial migration of spinal motor axons is controlled by external cues. Here, we show that the diwanka gene is required for growth cone migration of three identified subtypes of zebrafish primary motoneurons. In diwanka mutant embryos, motor growth cone migration within the spinal cord is unaffected but it is strongly impaired as motor axons enter their common path to the somites. Chimera analysis shows that diwanka gene activity is required in a small set of myotomal cells, called adaxial cells. We identified a subset of the adaxial cells to be sufficient to rescue the diwanka motor axon defect. Moreover, we show that this subset of adaxial cells delineates the common axonal path prior to axonogenesis, and we show that interactions between these adaxial cells and motor growth cones are likely to be transient. The studies demonstrate that a distinct population of myotomal cells plays a pivotal role in the early migration of zebrafish motor axons and identify the diwanka gene as a somite-derived cue required to establish an axonal path from the spinal cord to the somites.
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Battiston, Federico, Jeremy Guillon, Mario Chavez, Vito Latora i Fabrizio De Vico Fallani. "Multiplex core–periphery organization of the human connectome". Journal of The Royal Society Interface 15, nr 146 (wrzesień 2018): 20180514. http://dx.doi.org/10.1098/rsif.2018.0514.
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What is the core of the human brain is a fundamental question that has been mainly addressed by studying the anatomical connections between differently specialized areas, thus neglecting the possible contributions from their functional interactions. While many methods are available to identify the core of a network when connections between nodes are all of the same type, a principled approach to define the core when multiple types of connectivity are allowed is still lacking. Here, we introduce a general framework to define and extract the core–periphery structure of multi-layer networks by explicitly taking into account the connectivity patterns at each layer. We first validate our algorithm on synthetic networks of different size and density, and with tunable overlap between the cores at different layers. We then use our method to merge information from structural and functional brain networks, obtaining in this way an integrated description of the core of the human connectome. Results confirm the role of the main known cortical and subcortical hubs, but also suggest the presence of new areas in the sensori-motor cortex that are crucial for intrinsic brain functioning. Taken together these findings provide fresh evidence on a fundamental question in modern neuroscience and offer new opportunities to explore the mesoscale properties of multimodal brain networks.
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Fort, Timothy J., Vladimir Brezina i Mark W. Miller. "Regulation of the Crab Heartbeat by FMRFamide-Like Peptides: Multiple Interacting Effects on Center and Periphery". Journal of Neurophysiology 98, nr 5 (listopad 2007): 2887–902. http://dx.doi.org/10.1152/jn.00558.2007.
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We are studying the functional “logic” of neuromodulatory actions in a simple central pattern generator (CPG)-effector system, the heart of the blue crab Callinectes sapidus. The rhythmic contractions of this heart are neurogenic, driven by rhythmic motor patterns generated by the cardiac ganglion (CG). Here we used anatomical and physiological methods to examine the sources and actions on the system of the FMRFamide-like peptides (FLPs) TNRNFLRFamide (F1), SDRNFLRFamide (F2), and GYNRSFLRFamide, an authentic Callinectes FLP. Immunohistochemical localization revealed a plexus of FLP-immunoreactive fibers in the pericardial organs (POs), from which modulators are released to reach the heart as circulating neurohormones. Combined backfill and immunohistochemical experiments indicated that the FLPs in the POs originated in the CNS, from large neurosecretory cells in the B cluster of the first thoracic neuromere. In physiological experiments, we examined the actions of the FLPs on the intact working heart, on the semi-intact heart in which we could record the motor patterns as well as the muscle contractions, on the isolated CG, and in a preparation developed to assess direct actions on the muscle with controlled patterns of motor neuron spikes. The FLPs had strong positive chronotropic and inotropic effects. Dissection of these effects suggested that they were produced through at least two primary actions of the FLPs exerted both on the heart muscle and on the CG. These primary actions elicited numerous secondary consequences mediated by the feedforward and feedback interactions that integrate the activity of the complete, coupled CPG-effector system.
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Frolova, Liudmyla Serhiivna, Nataliia Pavlivna Chernenko i YuriyOleksiyovych Petrenko. "FEATURES OF THE VISUAL-MOTOR REACTION OF YOUNG VOLLEYBALL PLAYERS AND ITS IMPACTON THE ACCURACY OF THE ATTACKING BLOW". CHERKASY UNIVERSITY BULLETIN: BIOLOGICAL SCIENCES SERIES, nr 2 (2021): 71–79. http://dx.doi.org/10.31651/2076-5835-2018-1-2021-2-71-79.
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Introduction.The high speed and accuracy of the visual-motor reaction are the basis for the formation of the precision of volleyball players' movements. However, the visual-motor reaction of young volleyball players and its effect on the accuracy of an attack strike has not been studied.Purpose.Establishing features of the visual-motor reaction of young volleyball players with the direction of the periphery of the vision during the visual perception of moving objects and their influence on the accuracy of the attacking blow, taking into account motor asymmetry.Methods and material. 66 femaile volleyball players (7-16 years old) were examined. Technical preparedness of 22 femaile volleyball players (14-16 years old) were researched. A computer-based visual-response program and an impact test were used.Results.The dependence of the motor action on the accuracy of the reaction to the object moving is shown.At binocular perception,7-9-year-old volleyball players are dominated by the processes of excitation both in the general hit and in the reaction to the irritants presented fromthe left and fromthe rightsides. Volleyball players 13-16 years demonstrated the balance of nerve processes.Inhibition processes prevailed for athletes 10–12 years old. Proximity to balance of nervous processes was observed for 13–16 year olds when perceived with the left eye. The results of the study showed the correlation of the accuracy of the reaction with the accuracy of the attacking blow in the binocular and monocular perception of moving objects.Originality.Data on sensorimotor reactions in volleyball have been expanded. Taking into account the versatile perception of moving objects.Conclusions.Sensory prerequisites for the formation of the accuracy of an attack hit of young volleyball players are considered. The accuracy of the attacking blow by the right (dominant) hand depends on the accuracy of the reaction to the object moving from above-below with binocular perception. The connection of the accuracy of the reaction to a moving object from above with the accuracy of the attacking blow to the left area of the volleyball court increases significantly with the perception of the left eye. The accuracy of the reaction to the moving object from the right-left is less significant for the accuracy of the attacking blow by the right (the dominant) hand compared with the reaction to the object moving from above-below.Keywords.reaction to a moving object, periphery ofvisual perception, motor accuracy, motor asymmetry, excitation and inhibition of the nervous system.
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Wubbolts, R., M. Fernandez-Borja, I. Jordens, E. Reits, S. Dusseljee, C. Echeverri, R. B. Vallee i J. Neefjes. "Opposing motor activities of dynein and kinesin determine retention and transport of MHC class II-containing compartments". Journal of Cell Science 112, nr 6 (15.03.1999): 785–95. http://dx.doi.org/10.1242/jcs.112.6.785.
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MHC class II molecules exert their function at the cell surface by presenting to T cells antigenic fragments that are generated in the endosomal pathway. The class II molecules are targetted to early lysosomal structures, termed MIIC, where they interact with antigenic fragments and are subsequently transported to the cell surface. We previously visualised vesicular transport of MHC class II-containing early lysosomes from the microtubule organising centre (MTOC) region towards the cell surface in living cells. Here we show that the MIIC move bidirectionally in a ‘stop-and-go’ fashion. Overexpression of a motor head-deleted kinesin inhibited MIIC motility, showing that kinesin is the motor that drives its plus end transport towards the cell periphery. Cytoplasmic dynein mediates the return of vesicles to the MTOC area and effectively retains the vesicles at this location, as assessed by inactivation of dynein by overexpression of dynamitin. Our data suggest a retention mechanism that determines the perinuclear accumulation of MIIC, which is the result of dynein activity being superior over kinesin activity. The bidirectional nature of MIIC movement is the result of both kinesin and dynein acting reciprocally on the MIIC during its transport. The motors may be the ultimate targets of regulatory kinases since the protein kinase inhibitor staurosporine induces a massive release of lysosomal vesicles from the MTOC region that is morphologically similar to that observed after inactivation of the dynein motor.
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Kendrick, Agnieszka A., Andrea M. Dickey, William B. Redwine, Phuoc Tien Tran, Laura Pontano Vaites, Monika Dzieciatkowska, J. Wade Harper i Samara L. Reck-Peterson. "Hook3 is a scaffold for the opposite-polarity microtubule-based motors cytoplasmic dynein-1 and KIF1C". Journal of Cell Biology 218, nr 9 (18.07.2019): 2982–3001. http://dx.doi.org/10.1083/jcb.201812170.
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The unidirectional and opposite-polarity microtubule-based motors, dynein and kinesin, drive long-distance intracellular cargo transport. Cellular observations suggest that opposite-polarity motors may be coupled. We recently identified an interaction between the cytoplasmic dynein-1 activating adaptor Hook3 and the kinesin-3 KIF1C. Here, using in vitro reconstitutions with purified components, we show that KIF1C and dynein/dynactin can exist in a complex scaffolded by Hook3. Full-length Hook3 binds to and activates dynein/dynactin motility. Hook3 also binds to a short region in the “tail” of KIF1C, but unlike dynein/dynactin, this interaction does not activate KIF1C. Hook3 scaffolding allows dynein to transport KIF1C toward the microtubule minus end, and KIF1C to transport dynein toward the microtubule plus end. In cells, KIF1C can recruit Hook3 to the cell periphery, although the cellular role of the complex containing both motors remains unknown. We propose that Hook3’s ability to scaffold dynein/dynactin and KIF1C may regulate bidirectional motility, promote motor recycling, or sequester the pool of available dynein/dynactin activating adaptors.
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Caton, A., A. Hacker, A. Naeem, J. Livet, F. Maina, F. Bladt, R. Klein, C. Birchmeier i S. Guthrie. "The branchial arches and HGF are growth-promoting and chemoattractant for cranial motor axons". Development 127, nr 8 (15.04.2000): 1751–66. http://dx.doi.org/10.1242/dev.127.8.1751.
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During development, cranial motor neurons extend their axons along distinct pathways into the periphery. For example, branchiomotor axons extend dorsally to leave the hindbrain via large dorsal exit points. They then grow in association with sensory ganglia, to their targets, the muscles of the branchial arches. We have investigated the possibility that pathway tissues might secrete diffusible chemorepellents or chemoattractants that guide cranial motor axons, using co-cultures in collagen gels. We found that explants of dorsal neural tube or hindbrain roof plate chemorepelled cranial motor axons, while explants of cranial sensory ganglia were weakly chemoattractive. Explants of branchial arch mesenchyme were strongly growth-promoting and chemoattractive for cranial motor axons. Enhanced and oriented axon outgrowth was also elicited by beads loaded with Hepatocyte Growth Factor (HGF); antibodies to this protein largely blocked the outgrowth and orientation effects of the branchial arch on motor axons. HGF was expressed in the branchial arches, whilst Met, which encodes an HGF receptor, was expressed by subpopulations of cranial motor neurons. Mice with targetted disruptions of HGF or Met showed defects in the navigation of hypoglossal motor axons into the branchial region. Branchial arch tissue may thus act as a target-derived factor that guides motor axons during development. This influence is likely to be mediated partly by Hepatocyte Growth Factor, although a component of branchial arch-mediated growth promotion and chemoattraction was not blocked by anti-HGF antibodies.
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Pinter, Ilona J., Arthur J. van Soest, Maarten F. Bobbert i Jeroen B. J. Smeets. "Conclusions on motor control depend on the type of model used to represent the periphery". Biological Cybernetics 106, nr 8-9 (7.08.2012): 441–51. http://dx.doi.org/10.1007/s00422-012-0505-7.
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Tuma, M. Carolina, Andrew Zill, Nathalie Le Bot, Isabelle Vernos i Vladimir Gelfand. "Heterotrimeric Kinesin II Is the Microtubule Motor Protein Responsible for Pigment Dispersion in Xenopus Melanophores". Journal of Cell Biology 143, nr 6 (14.12.1998): 1547–58. http://dx.doi.org/10.1083/jcb.143.6.1547.
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Melanophores move pigment organelles (melanosomes) from the cell center to the periphery and vice-versa. These bidirectional movements require cytoplasmic microtubules and microfilaments and depend on the function of microtubule motors and a myosin. Earlier we found that melanosomes purified from Xenopus melanophores contain the plus end microtubule motor kinesin II, indicating that it may be involved in dispersion (Rogers, S.L., I.S. Tint, P.C. Fanapour, and V.I. Gelfand. 1997. Proc. Natl. Acad. Sci. USA. 94: 3720–3725). Here, we generated a dominant-negative construct encoding green fluorescent protein fused to the stalk-tail region of Xenopus kinesin-like protein 3 (Xklp3), the 95-kD motor subunit of Xenopus kinesin II, and introduced it into melanophores. Overexpression of the fusion protein inhibited pigment dispersion but had no effect on aggregation. To control for the specificity of this effect, we studied the kinesin-dependent movement of lysosomes. Neither dispersion of lysosomes in acidic conditions nor their clustering under alkaline conditions was affected by the mutant Xklp3. Furthermore, microinjection of melanophores with SUK4, a function-blocking kinesin antibody, inhibited dispersion of lysosomes but had no effect on melanosome transport. We conclude that melanosome dispersion is powered by kinesin II and not by conventional kinesin. This paper demonstrates that kinesin II moves membrane-bound organelles.
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Finlay, Barbara L., Flora Hinz i Richard B. Darlington. "Mapping behavioural evolution onto brain evolution: the strategic roles of conserved organization in individuals and species". Philosophical Transactions of the Royal Society B: Biological Sciences 366, nr 1574 (27.07.2011): 2111–23. http://dx.doi.org/10.1098/rstb.2010.0344.
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The pattern of individual variation in brain component structure in pigs, minks and laboratory mice is very similar to variation across species in the same components, at a reduced scale. This conserved pattern of allometric scaling resembles robotic architectures designed to be robust to changes in computing power and task demands, and may reflect the mechanism by which both growing and evolving brains defend basic sensory, motor and homeostatic functions at multiple scales. Conserved scaling rules also have implications for species-specific sensory and social communication systems, motor competencies and cognitive abilities. The role of relative changes in neuron number in the central nervous system in producing species-specific behaviour is thus highly constrained, while changes in the sensory and motor periphery, and in motivational and attentional systems increase in probability as the principal loci producing important changes in functional neuroanatomy between species. By their nature, these loci require renewed attention to development and life history in the initial organization and production of species-specific behavioural abilities.
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Amri, Lahcen, Smail Zouggar, Jean-Frédéric Charpentier, Mohamed Kebdani, Abdelhamid Senhaji, Abdelilah Attar i Farid Bakir. "Design and Optimization of Synchronous Motor Using PM Halbach Arrays for Rim-Driven Counter-Rotating Pump". Energies 16, nr 7 (28.03.2023): 3070. http://dx.doi.org/10.3390/en16073070.
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This document deals with the design of a Permanent Magnet Synchronous Motor (PMSM) to peripherally drive a counter-rotating pump inducer. The motor/pump is associated using a rim-driven principle where the motor’s active parts are located at the periphery of the inducer blades. It proposes using a Halbach array of permanent magnets for the active rotor of the motor. This solution allows the generation of a Sinusoidal Electromotive Force (EMF). Therefore, a more stable electromagnetic torque is reached. An optimum geometry suitable for the inducer specifications while respecting operational constraints is determined. The obtained geometry is then simulated using the Finite Element Method. The results are satisfactory in terms of average torque and EMF waveform. Use of the Halbach array allows a significant improvement of the flux density in the air gap compared to a designed surface-mounted machine. The experimental validation will be performed once the prototype is realized in the Laboratory of Fluid Engineering and Energy systems (LISFE).
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Torres, Vanessa O., Katie Poinsatte, Sterling B. Ortega, Xiangmei Kong, Erik J. Plautz, Denise M. O. Ramirez, Apoorva Ajay, Julian P. Meeks, Mark P. Goldberg i Ann M. Stowe. "Characterizing region-specific lymphocyte migration within the post-stroke brain". Journal of Immunology 204, nr 1_Supplement (1.05.2020): 72.11. http://dx.doi.org/10.4049/jimmunol.204.supp.72.11.
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Abstract Background Studies in our lab show that while B cell-depleted mice exhibit motor deficits, impaired neurogenesis, increased anxiety, and spatial memory deficits after stroke, CD8 T cell depletion reduces post-stroke motor deficits. Therefore, we hypothesized that B cells migrate into brain regions outside the infarct to promote post-stroke motor and cognitive recovery, unlike pro-inflammatory CD8 T cells that migrate to the area of injury. Methods Naïve donor B or CD8 T cells were labeled with e450 dye and injected i.v. into recipient mice at 7, 24, 48 and 72h after receiving a 60-minute transient middle cerebral artery occlusion (tMCAo). Peripheral and brain lymphocyte migration was assessed using flow cytometry and serial two-photon tomography (STPT) 96h after tMCAo. Results e450+ lymphocytes were detected in the periphery 96h after stroke. STPT co-registered with the Common Coordinate Framework (Allen Institute) created a 3D brain reconstruction that identified lymphocyte diapedesis. B cells were found bilaterally in areas outside the ischemic penumbra, such as the olfactory areas (p<0.05) and dentate gyrus (p<0.05), whereas CD8 T cells migrated into ipsilesional areas including the somatosensory cortex (p<0.01) and brainstem (p<0.01). Conclusions B cell diapedesis differs distinctly from that of CD8 T cells throughout the ischemic brain. While B cells migrate bilaterally into brain regions mediating cognitive deficits and neurogenesis, CD8 T cells exhibit greater unilateral migration into the injured hemisphere, including motor and sensory-related areas. Future directions will determine if the spatial location of CD8 T cells or B cells mediates post-stroke pathology or supports functional recovery, respectively.
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Munson, John B., Robert C. Foehring, Lorne M. Mendell i Tessa Gordon. "Fast-to-Slow Conversion Following Chronic Low-Frequency Activation of Medial Gastrocnemius Muscle in Cats. II. Motoneuron Properties". Journal of Neurophysiology 77, nr 5 (1.05.1997): 2605–15. http://dx.doi.org/10.1152/jn.1997.77.5.2605.
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Munson, John B., Robert C. Foehring, Lorne M. Mendell, and Tessa Gordon. Fast-to-slow conversion following chronic low-frequency activation of medial gastrocnemius muscle in cats. II. Motoneuron properties. J. Neurophysiol. 77: 2605–2615, 1997. Chronic stimulation (for 2–3 mo) of the medial gastrocnemius (MG) muscle nerve by indwelling electrodes renders the normally heterogeneous MG muscle mechanically and histochemically slow (type SO). We tested the hypothesis that motoneurons of MG muscle thus made type SO by chronic stimulation would also convert to slow phenotype. Properties of all single muscle units became homogeneously type SO (slowly contracting, nonfatiguing, nonsagging contraction during tetanic activation). Motoneuron electrical properties were also modified in the direction of type S, fatigue-resistant motor units. Two separate populations were identified (on the basis of afterhyperpolarization, rheobase, and input resistance) that likely correspond to motoneurons that had been fast (type F) or type S before stimulation. Type F motoneurons, although modified by chronic stimulation, were not converted to the type S phenotype, despite apparent complete conversion of their muscle units to the slow oxidative type (type SO). Muscle units of the former type F motor units were faster and/or more powerful than those of the former type S motor units, indicating some intrinsic regulation of motor unit properties. Experiments in which chronic stimulation was applied to the MG nerve cross-regenerated into skin yielded changes in motoneuron properties similar to those above, suggesting that muscle was not essential for the effects observed. Modulation of group Ia excitatory postsynaptic potential (EPSP) amplitude during high-frequency trains, which in normal MG motoneurons can be either positive or negative, was negative in 48 of 49 chronically stimulated motoneurons. Negative modulation is characteristic of EPSPs in motoneurons of most fatigue-resistant motor units. The general hypothesis of a periphery-to-motoneuron retrograde mechanism was supported, although the degree of control exerted by the periphery may vary: natural type SO muscle appears especially competent to modify motoneuron properties. We speculate that activity-dependent regulation of the neurotrophin-(NT) 4/5 in muscle plays an important role in controlling muscle and motoneuron properties.
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Müller, Thomas. "The Impact of COMT-inhibition on Gastrointestinal Levodopa Absorption in Patients with Parkinson's Disease". Clinical Medicine Insights: Therapeutics 2 (styczeń 2010): CMT.S1169. http://dx.doi.org/10.4137/cmt.s1169.
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The drug Levodopa (LD) is an efficient compound for the treatment of patients with Parkinson's disease (PD). Its short half life generates plasma behaviour of LD with peaks and troughs. Therefore, following the LD transport into the brain and the conversion to dopamine, an alternating stimulation of nigrostriatal postsynaptic dopamine receptors takes place. In the long term these fluctuations of dopamine concentrations supports onset of motor complications (MC) in PD patients. General opinion is that loss of central compensatory mechanisms of dopamine metabolism is responsible for the development of MC. However, in the periphery, LD troughs are preponderantly associated with the MC wearing off, which is the reappearance of motor symptoms with decreasing drug effect. Addition of the catechol-O-methyltransferase (COMT) inhibitor Entacapone (EN) to LD/carbidopa (CD) improved wearing off, since EN prolongs LD half life and avoids troughs. Plasma LD peaks are mostly related to the clinical manifestation of the MC dyskinesia, which appear as involuntary movements. One time addition of EN to a LD/CD formulation showed no increase of peripheral maximum LD concentration. But repeat combination of EN to each LD/CD intake elevated plasma LD bioavailability and peaks. Therefore switch from a LD/CD–-to a LD/CD/EN regime may also ask for reduction of LD/CD dosing or delay of the next LD/CD intake, to avoid onset of the most common peak dose dyskinesia. In conclusion, pharmacokinetic studies on peripheral LD metabolism and mode of intake underline their importance as peripheral components for MC manifestations in PD patients.
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Sonner, Patrick M., i David R. Ladle. "Early postnatal development of GABAergic presynaptic inhibition of Ia proprioceptive afferent connections in mouse spinal cord". Journal of Neurophysiology 109, nr 8 (15.04.2013): 2118–28. http://dx.doi.org/10.1152/jn.00783.2012.
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Sensory feedback is critical for normal locomotion and adaptation to external perturbations during movement. Feedback provided by group Ia afferents influences motor output both directly through monosynaptic connections and indirectly through spinal interneuronal circuits. For example, the circuit responsible for reciprocal inhibition, which acts to prevent co-contraction of antagonist flexor and extensor muscles, is driven by Ia afferent feedback. Additionally, circuits mediating presynaptic inhibition can limit Ia afferent synaptic transmission onto central neuronal targets in a task-specific manner. These circuits can also be activated by stimulation of proprioceptive afferents. Rodent locomotion rapidly matures during postnatal development; therefore, we assayed the functional status of reciprocal and presynaptic inhibitory circuits of mice at birth and compared responses with observations made after 1 wk of postnatal development. Using extracellular physiological techniques from isolated and hemisected spinal cord preparations, we demonstrate that Ia afferent-evoked reciprocal inhibition is as effective at blocking antagonist motor neuron activation at birth as at 1 wk postnatally. In contrast, at birth conditioning stimulation of muscle nerve afferents failed to evoke presynaptic inhibition sufficient to block functional transmission at synapses between Ia afferents and motor neurons, even though dorsal root potentials could be evoked by stimulating the neighboring dorsal root. Presynaptic inhibition at this synapse was readily observed, however, at the end of the first postnatal week. These results indicate Ia afferent feedback from the periphery to central spinal circuits is only weakly gated at birth, which may provide enhanced sensitivity to peripheral feedback during early postnatal experiences.
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Huttenlocher, Peter R., i Christine Bonnier. "Effects of changes in the periphery on development of the corticospinal motor system in the rat". Developmental Brain Research 60, nr 2 (czerwiec 1991): 253–60. http://dx.doi.org/10.1016/0165-3806(91)90054-m.
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Nowacek, Ari S., i Dale R. Sengelaub. "Estrogenic support of motoneuron dendritic growth via the neuromuscular periphery in a sexually dimorphic motor system". Journal of Neurobiology 66, nr 9 (2006): 962–76. http://dx.doi.org/10.1002/neu.20274.
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Buckingham, Martin J., Kerry R. Crone, William S. Ball, Thomas A. Tomsick, Thomas S. Berger i John M. Tew. "Traumatic Intracranial Aneurysms in Childhood: Two Cases and a Review of the Literature". Neurosurgery 22, nr 2 (1.02.1988): 398–408. http://dx.doi.org/10.1227/00006123-198802000-00022.
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Abstract Traumatic intracranial aneurysms in childhood are rare. To date, 67 well-documented cases in children have been reported. We present 2 additional cases and review the literature. Traumatic aneurysms can best be categorized based on mechanism of injury and location. Aneurysms secondary to penetrating trauma occur most commonly in teenage boys suffering gunshot wounds. Aneurysms secondary to nonpenetrating trauma occur at the skull base or in the periphery, with motor vehicle accidents and falls as the most common modes of injury. Skull base traumatic aneurysms most commonly involve the petrous, cavernous, or supraclinoid carotid artery and also show a predominance in teenage boys. Peripheral traumatic aneurysms can further be divided into distal anterior cerebral artery aneurysms secondary to trauma against the falcine edge and distal cortical artery aneurysms associated with an overlying skull fracture. Peripheral traumatic aneurysms tend to occur in younger patients with a less marked male predominance. Two-thirds of the patients suffered symptomatic aneurysmal hemorrhage, with an associated mortality rate of 31%. The clinical presentation, diagnosis, and treatment of traumatic intracranial aneurysms are discussed. (Neurosurgery 22:398-408, 1988)
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Buscaglia, Carlos A., Isabelle Coppens, Wim G. J. Hol i Victor Nussenzweig. "Sites of Interaction between Aldolase and Thrombospondin-related Anonymous Protein in Plasmodium". Molecular Biology of the Cell 14, nr 12 (grudzień 2003): 4947–57. http://dx.doi.org/10.1091/mbc.e03-06-0355.
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Gliding motility and host cell invasion by apicomplexan parasites are empowered by an acto-myosin motor located underneath the parasite plasma membrane. The motor is connected to host cell receptors through trans-membrane invasins belonging to the thrombospondin-related anonymous protein (TRAP) family. A recent study indicates that aldolase bridges the cytoplasmic tail of MIC2, the homologous TRAP protein in Toxoplasma, and actin. Here, we confirm these unexpected findings in Plasmodium sporozoites and identify conserved features of the TRAP family cytoplasmic tail required to bind aldolase: a subterminal tryptophan residue and two noncontiguous stretches of negatively charged amino acids. The aldolase substrate and other compounds that bind to the active site inhibit its interaction with TRAP and with F-actin, suggesting that the function of the motor is metabolically regulated. Ultrastructural studies in salivary gland sporozoites localize aldolase to the periphery of the secretory micronemes containing TRAP. Thus, the interaction between aldolase and the TRAP tail takes place during or preceding the biogenesis of the micronemes. The release of their contents in the anterior pole of the parasite upon contact with the target cells should bring simultaneously aldolase, TRAP and perhaps F-actin to the proper subcellular location where the motor is engaged.
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Carata, Elisabetta, Marco Muci, Simona Di Giulio, Stefania Mariano i Elisa Panzarini. "Looking to the Future of the Role of Macrophages and Extracellular Vesicles in Neuroinflammation in ALS". International Journal of Molecular Sciences 24, nr 14 (8.07.2023): 11251. http://dx.doi.org/10.3390/ijms241411251.
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Neuroinflammation is a common pathological feature of amyotrophic lateral sclerosis (ALS). Although scientific evidence to date does not allow defining neuroinflammation as an ALS trigger, its role in exacerbating motor neuron (MNs) degeneration and disease progression is attracting research interest. Activated CNS (Central Nervous System) glial cells, proinflammatory peripheral and infiltrated T lymphocytes and monocytes/macrophages, as well as the immunoreactive molecules they release, represent the active players for the role of immune dysregulation enhancing neuroinflammation. The crosstalk between the peripheral and CNS immune cells significantly correlates with the survival of ALS patients since the modification of peripheral macrophages can downregulate inflammation at the periphery along the nerves and in the CNS. As putative vehicles for misfolded protein and inflammatory mediators between cells, extracellular vesicles (EVs) have also drawn particular attention in the field of ALS. Both CNS and peripheral immune cells release EVs, which are able to modulate the behavior of neighboring recipient cells; unfortunately, the mechanisms involved in EVs-mediated communication in neuroinflammation remain unclear. This review aims to synthesize the current literature regarding EV-mediated cell-to-cell communication in the brain under ALS, with a particular point of view on the role of peripheral macrophages in responding to inflammation to understand the biological process and exploit it for ALS management.
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Diagouraga, Boubou, Alexei Grichine, Arnold Fertin, Jin Wang, Saadi Khochbin i Karin Sadoul. "Motor-driven marginal band coiling promotes cell shape change during platelet activation". Journal of Cell Biology 204, nr 2 (13.01.2014): 177–85. http://dx.doi.org/10.1083/jcb.201306085.
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Platelets float in the blood as discoid particles. Their shape is maintained by microtubules organized in a ring structure, the so-called marginal band (MB), in the periphery of resting platelets. Platelets are activated after vessel injury and undergo a major shape change known as disc to sphere transition. It has been suggested that actomyosin tension induces the contraction of the MB to a smaller ring. In this paper, we show that antagonistic microtubule motors keep the MB in its resting state. During platelet activation, dynein slides microtubules apart, leading to MB extension rather than contraction. The MB then starts to coil, thereby inducing the spherical shape of activating platelets. Newly polymerizing microtubules within the coiled MB will then take a new path to form the smaller microtubule ring, in concerted action with actomyosin tension. These results present a new view of the platelet activation mechanism and reveal principal mechanistic features underlying cellular shape changes.
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Jellema, T., i W. Heitler. "Peripheral control of the gain of a central synaptic connection between antagonistic motor neurones in the locust". Journal of Experimental Biology 199, nr 3 (1.03.1996): 613–25. http://dx.doi.org/10.1242/jeb.199.3.613.
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The metathoracic fast extensor tibiae (FETi) motor neurone of locusts is unusual amongst insect motor neurones because it makes output connections within the central nervous system as well as in the periphery. It makes excitatory chemical synaptic connections to most if not all of the antagonist flexor tibiae motor neurones. The gain of the FETi-flexor connection is dependent on the peripheral conditions at the time of the FETi spike. This dependency has two aspects. First, sensory input resulting from the extensor muscle contraction can sum with the central excitatory postsynaptic potential (EPSP) to augment its falling phase if the tibia is restrained in the flexed position (initiating a tension-dependent reflex) or is free to extend (initiating a movement-dependent resistance reflex). This effect is thus due to simple postsynaptic summation of the central EPSP with peripheral sensory input. Second, the static tibial position at the time of the FETi spike can change the amplitude of the central EPSP, in the absence of any extensor muscle contraction. The EPSP can be up to 30 % greater in amplitude if FETi spikes with the tibia held flexed rather than extended. The primary sense organ mediating this effect is the femoral chordotonal organ. Evidence is presented suggesting that the mechanism underlying this change in gain may be specifically localised to the FETi-flexor connection, rather than being due to general position-dependent sensory feedback summing with the EPSP. The change in the amplitude of the central EPSP is probably not caused by general postsynaptic summation with tonic sensory input, since a diminution in the amplitude of the central EPSP caused by tibial extension is often accompanied by overall tonic excitation of the flexor motor neurone. Small but significant changes in the peak amplitude of the FETi spike have a positive correlation with changes in the EPSP amplitude, suggesting a likely presynaptic component to the mechanism of gain control. The change in amplitude of the EPSP can alter its effectiveness in producing flexor motor output and, thus, has functional significance. The change serves to augment the effectiveness of the FETi-flexor connection when the tibia is fully flexed, and thus to increase its adaptive advantage during the co-contraction preceding a jump or kick, and to reduce the effectiveness of the connection when the tibia is partially or fully extended, and thus to reduce its potentially maladaptive consequences during voluntary extension movements such as thrusting.
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Hafed, Ziad M., Chih-Yang Chen, Xiaoguang Tian, Matthias P. Baumann i Tong Zhang. "Active vision at the foveal scale in the primate superior colliculus". Journal of Neurophysiology 125, nr 4 (1.04.2021): 1121–38. http://dx.doi.org/10.1152/jn.00724.2020.
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The primate superior colliculus (SC) has recently been shown to possess both a large foveal representation as well as a varied visual processing repertoire. This structure is also known to contribute to eye movement generation. Here, we describe our current understanding of how SC visual and movement-related signals interact within the realm of small eye movements associated with the foveal scale of visuomotor behavior. Within the SC’s foveal representation, there is a full spectrum of visual, visual-motor, and motor-related discharge for fixational eye movements. Moreover, a substantial number of neurons only emit movement-related discharge when microsaccades are visually guided, but not when similar movements are generated toward a blank. This represents a particularly striking example of integrating vision and action at the foveal scale. Beyond that, SC visual responses themselves are strongly modulated, and in multiple ways, by the occurrence of small eye movements. Intriguingly, this impact can extend to eccentricities well beyond the fovea, causing both sensitivity enhancement and suppression in the periphery. Because of large foveal magnification of neural tissue, such long-range eccentricity effects are neurally warped into smaller differences in anatomical space, providing a structural means for linking peripheral and foveal visual modulations around fixational eye movements. Finally, even the retinal-image visual flows associated with tiny fixational eye movements are signaled fairly faithfully by peripheral SC neurons with relatively large receptive fields. These results demonstrate how studying active vision at the foveal scale represents an opportunity for understanding primate vision during natural behaviors involving ever-present foveating eye movements.
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Tokuo, Hiroshi, Katsuhide Mabuchi i Mitsuo Ikebe. "The motor activity of myosin-X promotes actin fiber convergence at the cell periphery to initiate filopodia formation". Journal of Cell Biology 179, nr 2 (22.10.2007): 229–38. http://dx.doi.org/10.1083/jcb.200703178.
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Filopodia are actin-rich fingerlike protrusions found at the leading edge of migrating cells and are believed to play a role in directional sensing. Previous studies have shown that myosin-X (myoX) promotes filopodia formation and that this is mediated through its ability to deliver specific cargoes to the cell periphery (Tokuo, H., and M. Ikebe. 2004. Biochem Biophys. Commun. 319:214–220; Zhang, H., J.S. Berg, Z. Li, Y. Wang, P. Lang, A.D. Sousa, A. Bhaskar, R.E. Cheney, and S. Stromblad. 2004. Nat. Cell Biol. 6:523–531; Bohil, A.B., B.W. Robertson, and R.E. Cheney. 2006. Proc. Natl. Acad. Sci. USA. 103:12411–12416; Zhu, X.J., C.Z. Wang, P.G. Dai, Y. Xie, N.N. Song, Y. Liu, Q.S. Du, L. Mei, Y.Q. Ding, and W.C. Xiong. 2007. Nat. Cell Biol. 9:184–192). In this study, we show that the motor function of myoX and not the cargo function is critical for initiating filopodia formation. Using a dimer-inducing technique, we find that myoX lacking its cargo-binding tail moves laterally at the leading edge of lamellipodia and induces filopodia in living cells. We conclude that the motor function of the two-headed form of myoX is critical for actin reorganization at the leading edge, leading to filopodia formation.
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Kurtzer, Isaac, Troy M. Herter i Stephen H. Scott. "Nonuniform Distribution of Reach-Related and Torque-Related Activity in Upper Arm Muscles and Neurons of Primary Motor Cortex". Journal of Neurophysiology 96, nr 6 (grudzień 2006): 3220–30. http://dx.doi.org/10.1152/jn.00110.2006.
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The present study examined the activity of primate shoulder and elbow muscles using a novel reaching task. We enforced similar patterns of center-out movement while the animals countered viscous loads at their shoulder, elbow, both joints, or neither joint. Accordingly, we could examine reach-related activity during the unloaded condition and torque-related activity by comparing activity across load conditions. During unloaded reaching the upper arm muscles exhibited a bimodal distribution of preferred hand direction. Maximal reach-related activity occurred with hand movements mostly toward or away from the body. Arm muscles also exhibited a bimodal distribution of their preferred torque direction. Maximal torque-related activity typically occurred with shoulder-extension/elbow-flexion torque or shoulder-flexion/elbow-extension torque. Similar biases in reach-related and torque-related activity could be reproduced by optimizing a global measure of muscle activity. These biases were also observed in the neural activity of primary motor cortex (M1). The parallels between M1 and muscular activity demonstrate another link between motor cortical processing and the motor periphery and may reflect an optimization process performed by the sensorimotor system.
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van Leeuwen, Hans, Gill Elliott i Peter O'Hare. "Evidence of a Role for Nonmuscle Myosin II in Herpes Simplex Virus Type 1 Egress". Journal of Virology 76, nr 7 (1.04.2002): 3471–81. http://dx.doi.org/10.1128/jvi.76.7.3471-3481.2002.
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ABSTRACT After cell entry, herpes simplex virus (HSV) particles are transported through the host cell cytoplasm to nuclear pores. Following replication, newly synthesized virus particles are transported back to the cell periphery via a complex pathway including a cytoplasmic phase involving some form of unenveloped particle. These various transport processes are likely to make use of one or more components of the cellular cytoskeletal systems and associated motor proteins. Here we report that the HSV type 1 (HSV-1) major tegument protein, VP22, interacts with the actin-associated motor protein nonmuscle myosin IIA (NMIIA). HSV-1 infection resulted in reorganization of NMIIA, inducing retraction of NMIIA from the cell periphery and condensation into a spoke-like distribution around the nucleus along with a second effect of accumulation in a perinuclear cluster. VP22 did not appear to colocalize with the reorganized cagelike distribution of NMIIA. However, VP22 has been previously reported to localize in a perinuclear vesicular pattern, and significant overlap was observed between this pattern and the perinuclear clusters of NMIIA. Inhibition of the ATPase activity of NMIIA with the myosin-specific inhibitor butanedione monoxime impaired the formation of the perinuclear vesicular VP22 accumulations and also the release of virus into the extracellular medium while having much less effect on the yield of cell-associated virus. Virus infection frequently results in the induction of highly extended processes emanating from the infected cell, and we observed that VP22-containing particles line up along NMIIA-containing filaments which run through these protrusions.
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Pinder, J. C., R. E. Fowler, A. R. Dluzewski, L. H. Bannister, F. M. Lavin, G. H. Mitchell, R. J. Wilson i W. B. Gratzer. "Actomyosin motor in the merozoite of the malaria parasite, Plasmodium falciparum: implications for red cell invasion". Journal of Cell Science 111, nr 13 (1.07.1998): 1831–39. http://dx.doi.org/10.1242/jcs.111.13.1831.
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The genome of the malaria parasite, Plasmodium falciparum, contains a myosin gene sequence, which bears a close homology to one of the myosin genes found in another apicomplexan parasite, Toxoplasma gondii. A polyclonal antibody was generated against an expressed polypeptide of molecular mass 27,000, based on part of the deduced sequence of this myosin. The antibody reacted with the cognate antigen and with a component of the total parasite protein on immunoblots, but not with vertebrate striated or smooth muscle myosins. It did, however, recognise two components in the cellular protein of Toxoplasma gondii. The antibody was used to investigate stage-specificity of expression of the myosin (here designated Pf-myo1) in P. falciparum. The results showed that the protein is synthesised in mature schizonts and is present in merozoites, but vanishes after the parasite enters the red cell. Pf-myo1 was found to be largely, though not entirely, associated with the particulate parasite cell fraction and is thus presumably mainly membrane bound. It was not solubilised by media that would be expected to dissociate actomyosin or myosin filaments, or by non-ionic detergent. Immunofluorescence revealed that in the merozoite and mature schizont Pf-myo1 is predominantly located around the periphery of the cell. Immuno-gold electron microscopy also showed the presence of the myosin around almost the entire parasite periphery, and especially in the region surrounding the apical prominence. Labelling was concentrated under the plasma membrane but was not seen in the apical prominence itself. This suggests that Pf-myo1 is associated with the plasma membrane or with the outer membrane of the subplasmalemmal cisterna, which forms a lining to the plasma membrane, with a gap at the apical prominence. The results lead to a conjectural model of the invasion mechanism.
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Cardanho-Ramos, Carlos, i Vanessa Alexandra Morais. "Mitochondrial Biogenesis in Neurons: How and Where". International Journal of Molecular Sciences 22, nr 23 (2.12.2021): 13059. http://dx.doi.org/10.3390/ijms222313059.
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Neurons rely mostly on mitochondria for the production of ATP and Ca2+ homeostasis. As sub-compartmentalized cells, they have different pools of mitochondria in each compartment that are maintained by a constant mitochondrial turnover. It is assumed that most mitochondria are generated in the cell body and then travel to the synapse to exert their functions. Once damaged, mitochondria have to travel back to the cell body for degradation. However, in long cells, like motor neurons, this constant travel back and forth is not an energetically favourable process, thus mitochondrial biogenesis must also occur at the periphery. Ca2+ and ATP levels are the main triggers for mitochondrial biogenesis in the cell body, in a mechanism dependent on the Peroxisome-proliferator-activated γ co-activator-1α-nuclear respiration factors 1 and 2-mitochondrial transcription factor A (PGC-1α-NRF-1/2-TFAM) pathway. However, even though of extreme importance, very little is known about the mechanisms promoting mitochondrial biogenesis away from the cell body. In this review, we bring forward the evoked mechanisms that are at play for mitochondrial biogenesis in the cell body and periphery. Moreover, we postulate that mitochondrial biogenesis may vary locally within the same neuron, and we build upon the hypotheses that, in the periphery, local protein synthesis is responsible for giving all the machinery required for mitochondria to replicate themselves.
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Calvert, Jonathan S., Megan L. Gill, Margaux B. Linde, Daniel D. Veith, Andrew R. Thoreson, Cesar Lopez, Kendall H. Lee i in. "Voluntary Modulation of Evoked Responses Generated by Epidural and Transcutaneous Spinal Stimulation in Humans with Spinal Cord Injury". Journal of Clinical Medicine 10, nr 21 (24.10.2021): 4898. http://dx.doi.org/10.3390/jcm10214898.
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Transcutaneous (TSS) and epidural spinal stimulation (ESS) are electrophysiological techniques that have been used to investigate the interactions between exogenous electrical stimuli and spinal sensorimotor networks that integrate descending motor signals with afferent inputs from the periphery during motor tasks such as standing and stepping. Recently, pilot-phase clinical trials using ESS and TSS have demonstrated restoration of motor functions that were previously lost due to spinal cord injury (SCI). However, the spinal network interactions that occur in response to TSS or ESS pulses with spared descending connections across the site of SCI have yet to be characterized. Therefore, we examined the effects of delivering TSS or ESS pulses to the lumbosacral spinal cord in nine individuals with chronic SCI. During low-frequency stimulation, participants were instructed to relax or attempt maximum voluntary contraction to perform full leg flexion while supine. We observed similar lower-extremity neuromusculature activation during TSS and ESS when performed in the same participants while instructed to relax. Interestingly, when participants were instructed to attempt lower-extremity muscle contractions, both TSS- and ESS-evoked motor responses were significantly inhibited across all muscles. Participants with clinically complete SCI tested with ESS and participants with clinically incomplete SCI tested with TSS demonstrated greater ability to modulate evoked responses than participants with motor complete SCI tested with TSS, although this was not statistically significant due to a low number of subjects in each subgroup. These results suggest that descending commands combined with spinal stimulation may increase activity of inhibitory interneuronal circuitry within spinal sensorimotor networks in individuals with SCI, which may be relevant in the context of regaining functional motor outcomes.
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Snyder, Lawrence H., Aaron P. Batista i Richard A. Andersen. "Change in Motor Plan, Without a Change in the Spatial Locus of Attention, Modulates Activity in Posterior Parietal Cortex". Journal of Neurophysiology 79, nr 5 (1.05.1998): 2814–19. http://dx.doi.org/10.1152/jn.1998.79.5.2814.
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Snyder, Lawrence H., Aaron P. Batista, and Richard A. Andersen. Change in motor plan, without a change in the spatial locus of attention, modulates activity in posterior parietal cortex. J. Neurophysiol. 79: 2814–2819, 1998. The lateral intraparietal area (LIP) of macaque monkey, and a parietal reach region (PRR) medial and posterior to LIP, code the intention to make visually guided eye and arm movements, respectively. We studied the effect of changing the motor plan, without changing the locus of attention, on single neurons in these two areas. A central target was fixated while one or two sequential flashes occurred in the periphery. The first appeared either within the response field of the neuron being recorded or else on the opposite side of the fixation point. Animals planned a saccade (red flash) or reach (green flash) to the flash location. In some trials, a second flash 750 ms later could change the motor plan but never shifted attention: second flashes always occurred at the same location as the preceding first flash. Responses in LIP were larger when a saccade was instructed ( n = 20 cells), whereas responses in PRR were larger when a reach was instructed ( n = 17). This motor preference was observed for both first flashes and second flashes. In addition, the response to a second flash depended on whether it affirmed or countermanded the first flash; second flash responses were diminished only in the former case. Control experiments indicated that this differential effect was not due to stimulus novelty. These findings support a role for posterior parietal cortex in coding specific motor intention and are consistent with a possible role in the nonspatial shifting of motor intention.