Local control of veins: biomechanical, metabolic, and humoral aspects

1995 ◽  
Vol 75 (3) ◽  
pp. 611-666 ◽  
Author(s):  
E. Monos ◽  
V. Berczi ◽  
G. Nadasy
Keyword(s):  
Neural Control ◽  
Orthostatic Intolerance ◽  
Good Reason ◽  
Scientific Data ◽  
Venous System ◽  
Control Mechanisms ◽  
Critical Survey ◽  
Order Of Magnitude ◽  
Important Field ◽  
Effective Integration

The incidence of vein diseases (varicosity, thrombophlebitis, phlebosclerosis, orthostatic intolerance) is extremely high. In several countries it may exceed that of the arterial pathology by an order of magnitude. In the last decades, this recognition and the rapid accumulation of experimental data have resulted in a progressive reevaluation of the physiological significance of the venous system, which had been rather neglected earlier by scientists. The major aim of this review is to provide a critical survey of recent selected literature related to different physiological functions of the venous system as well as to biomechanical, metabolic, and humoral (ionic, hormonal) aspects of the local venous control. Local neural control mechanisms, including effects of catecholamines and other transmitters, are regarded to be beyond the scope of this work. At present, the synthesis of information available in the literature meets certain difficulties, because occasionally poorly defined methodological techniques and physiological parameters have been applied. On the other hand, a significant part of works dealing with venous physiology is excellent and inspirational. We have good reason to believe that the fast accumulation of reliable scientific data on this very important field will soon reach a new critical level, then an even more effective integration of knowledge will be possible.

Resituating cognitive mechanisms within heterarchical networks controlling physiology and behavior

2019 ◽  
Vol 29 (5) ◽  
pp. 620-639 ◽  
Author(s):  
William Bechtel
Keyword(s):  
Cognitive Control ◽  
Cognitive Science ◽  
Neural Control ◽  
Science Research ◽  
Control Mechanisms ◽  
Cognitive Mechanisms ◽  
Physiological Processes ◽  
High Level ◽  
And Behavior ◽  
Production Mechanisms

Cognitive science has traditionally focused on mechanisms involved in high-level reasoning and problem-solving processes. Such mechanisms are often treated as autonomous from but controlling underlying physiological processes. I offer a different perspective on cognition which starts with the basic production mechanisms through which organisms construct and repair themselves and navigate their environments and then I develop a framework for conceptualizing how cognitive control mechanisms form a heterarchical network that regulates production mechanisms. Many of these control mechanisms perform cognitive tasks such as evaluating circumstances and making decisions. Cognitive control mechanisms are present in individual cells, but in metazoans, intracellular control is supplemented by a nervous system in which a multitude of neural control mechanisms are organized heterarchically. On this perspective, high-level cognitive mechanisms are not autonomous, but are elements in larger heterarchical networks. This has implications for future directions in cognitive science research.

Formulation of “Stability Equations” and Derivation of New Constructions with Complete Systems of Design-formulae for Variable-speed Control Mechanisms

1953 ◽  
Vol 167 (1) ◽  
pp. 319-339
Author(s):  
M. S. Frenkel
Keyword(s):  
Nuclear Physics ◽  
Characteristic Curve ◽  
Mathematical Formulation ◽  
Control Mechanisms ◽  
Variable Speed ◽  
Speed Governor ◽  
Minimum Number ◽  
Order Of Magnitude ◽  
The Stability ◽  
Stable Characteristic

Requirements for stability are formulated mathematically and, through the “transformatory operations of mathematics”, yield a series of “stability equations” of ascending order which are generally applicable, for example to control mechanisms, electronics†, nuclear physics, etc. From these stability equations, the equation of the stable characteristic curve of a governor, and the differential equations of the oscillations of a governor-engine system, are derived. It emerges that the first part of the new oscillatory equation is identical with the whole of the differential equation in the literature to date (unchanged since Maxwell 1868)‡, while the important second part, which consists of terms of the same order of magnitude as the first part and which is the only one containing the equation of the stable characteristic curve, is lacking in literature. The stability equations classify all possible constructions of variable-speed governor according to “order of stability”, which signifies important operating properties. This classification accounts for the known shortcomings of conventional types. The stability equations, combined with the mathematical formulation of practical requirements (speed-adjustment with only one actuating motion, etc.), lead to new basic types of variable-speed governor, with complete systems of design equations. In addition to determining all unknown dimensions, this set of equations is important because it derives constructions of which the complexity increases with order of stability and, furthermore, a simple construction which provides any required high order of stability with the minimum number of adjustable components.

Autonomic Neural Control Mechanisms and the Release of Adrenal Steroids after Hypoglycaemia in Man

2008 ◽  
Vol 16 (S 1) ◽  
pp. 138-141 ◽  
Author(s):  
B. Frier ◽  
E. A. S. Al-Dujaili ◽  
R. J. M. Corrall ◽  
J. Pritchard ◽  
C. R. W. Edwards
Keyword(s):  
Neural Control ◽  
Control Mechanisms ◽  
Adrenal Steroids

scholarly journals Integration of auditory and somatosensory error signals in the neural control of speech movements

2011 ◽  
Vol 106 (2) ◽  
pp. 667-679 ◽  
Author(s):  
Yongqiang Feng ◽  
Vincent L. Gracco ◽  
Ludo Max
Keyword(s):  
Auditory Feedback ◽  
Neural Control ◽  
Dominant Role ◽  
Feedback Signal ◽  
Sensorimotor Adaptation ◽  
Auditory Modality ◽  
Control Mechanisms ◽  
Articulatory Movements ◽  
Jaw Opening ◽  
Jaw Position

We investigated auditory and somatosensory feedback contributions to the neural control of speech. In task I, sensorimotor adaptation was studied by perturbing one of these sensory modalities or both modalities simultaneously. The first formant (F1) frequency in the auditory feedback was shifted up by a real-time processor and/or the extent of jaw opening was increased or decreased with a force field applied by a robotic device. All eight subjects lowered F1 to compensate for the up-shifted F1 in the feedback signal regardless of whether or not the jaw was perturbed. Adaptive changes in subjects' acoustic output resulted from adjustments in articulatory movements of the jaw or tongue. Adaptation in jaw opening extent in response to the mechanical perturbation occurred only when no auditory feedback perturbation was applied or when the direction of adaptation to the force was compatible with the direction of adaptation to a simultaneous acoustic perturbation. In tasks II and III, subjects' auditory and somatosensory precision and accuracy were estimated. Correlation analyses showed that the relationships 1) between F1 adaptation extent and auditory acuity for F1 and 2) between jaw position adaptation extent and somatosensory acuity for jaw position were weak and statistically not significant. Taken together, the combined findings from this work suggest that, in speech production, sensorimotor adaptation updates the underlying control mechanisms in such a way that the planning of vowel-related articulatory movements takes into account a complex integration of error signals from previous trials but likely with a dominant role for the auditory modality.

scholarly journals MRI and CT-venography in the diagnosis of hemodynamic disturbances in patients with chronic lower extremities venous disorders. Part III. Possibilities of CT-investigation in diagnosing of venous hemodynamics violations

2021 ◽  
Vol 25 (4) ◽  
pp. 53-74
Author(s):  
E. V. Shajdakov ◽  
A. B. Sannikov ◽  
V. M. Emelyanenko ◽  
M. A. Rachkov ◽  
L. N. Kryukova ◽  
...  
Keyword(s):  
Lower Extremities ◽  
Scientific Data ◽  
Venous System ◽  
Venous Blood Flow ◽  
Technical Problems ◽  
Ct Venography ◽  
Vein Thrombosis ◽  
Venous Diseases ◽  
The World ◽  
Contrast Ct

As a result of solving a large number of technical problems (increasing the area of anatomical coverage and scanning speed, increasing the signal-to-noise ratio, improving spatial and contrast resolution, building a color image quality in 3D mode, significantly reducing the radiation dose), the method of computed tomography imaging of the vascular system has won a leading position in the world today. However, if CT Angiography is used everywhere and daily in the diagnosis of arterial pathology, this method has not yet received clinical recognition in patients with chronic venous diseases.This review of the literature analyzes the scientific data published in the world on the results of CT Venography. Methods of indirect and direct contrast CT Venography are described. The possibility of using contrast CT Venography in the diagnosis of deep vein thrombosis is shown, where the accuracy, sensitivity and specificity of the method according to foreign authors is up to 97.9%, 96.8% and 100%, respectively. This method acquires particular importance in the diagnosis of pelvic vein thrombosis and inferior Vena cava, where the informative value of USDS is lower. The second clinical direction that is actively developing today is the combined use of CT Venography and CT Angiopulmonography in the diagnosis of a deadly complication of pulmonary embolism. The prospects of these attempts are preferable by the following advantages: the single-time study and the absence of the need for additional administration of contrast agents, the speed of scanning, and obtaining additional information about the state of the peripheral venous system in patients with venous thromboembolism.Another and irreplaceable tool of contrast-enhanced CT Venography can become in the study of the features of the topographic and anatomical structure of the venous bed. Using their own research, the authors demonstrate the possibilities of direct CT Venography in the visualization of the venous system of the lower extremities.The need for more accurate topical diagnostics with 3D visualization of the venous system of the lower extremities and pelvis by CT-Venography is due to the growing interest in recent years of vascular and interventional surgeons to test and more actively implement endovasal methods of correction of venous blood flow in phlebological practice.

scholarly journals Emerging ideas and tools to study the emergent properties of the cortical neural circuits for voluntary motor control in non-human primates

F1000Research ◽  
2019 ◽  
Vol 8 ◽  
pp. 749 ◽  
Author(s):  
John F. Kalaska
Keyword(s):  
Motor Control ◽  
Neural Control ◽  
Neural Circuits ◽  
Neuron Activity ◽  
Emergent Properties ◽  
Control Mechanisms ◽  
Single Neurons ◽  
Electrode Arrays ◽  
Voluntary Motor ◽  
Neurophysiological Studies

For years, neurophysiological studies of the cerebral cortical mechanisms of voluntary motor control were limited to single-electrode recordings of the activity of one or a few neurons at a time. This approach was supported by the widely accepted belief that single neurons were the fundamental computational units of the brain (the “neuron doctrine”). Experiments were guided by motor-control models that proposed that the motor system attempted to plan and control specific parameters of a desired action, such as the direction, speed or causal forces of a reaching movement in specific coordinate frameworks, and that assumed that the controlled parameters would be expressed in the task-related activity of single neurons. The advent of chronically implanted multi-electrode arrays about 20 years ago permitted the simultaneous recording of the activity of many neurons. This greatly enhanced the ability to study neural control mechanisms at the population level. It has also shifted the focus of the analysis of neural activity from quantifying single-neuron correlates with different movement parameters to probing the structure of multi-neuron activity patterns to identify the emergent computational properties of cortical neural circuits. In particular, recent advances in “dimension reduction” algorithms have attempted to identify specific covariance patterns in multi-neuron activity which are presumed to reflect the underlying computational processes by which neural circuits convert the intention to perform a particular movement into the required causal descending motor commands. These analyses have led to many new perspectives and insights on how cortical motor circuits covertly plan and prepare to initiate a movement without causing muscle contractions, transition from preparation to overt execution of the desired movement, generate muscle-centered motor output commands, and learn new motor skills. Progress is also being made to import optical-imaging and optogenetic toolboxes from rodents to non-human primates to overcome some technical limitations of multi-electrode recording technology.

scholarly journals Distinct Proximal and Distal Corticospinal Signals Embed Limb Dynamics Through the Modulation of Stiffness

2019 ◽  
Author(s):  
R. L. Hardesty ◽  
P. H. Ellaway ◽  
V. Gritsenko
Keyword(s):  
Nervous System ◽  
Physical Properties ◽  
Neural Control ◽  
Primary Motor Cortex ◽  
Equations Of Motion ◽  
Task Demands ◽  
The Body ◽  
Control Mechanisms ◽  
Neural Signals ◽  
Limb Dynamics

AbstractThe complexities of the human musculoskeletal system and its interactions with the environment creates a difficult challenge for the neural control of movement. The consensus is that the nervous system solves this challenge by embedding the dynamical properties of the body and the environment. However, the modality of control signals and how they are generated appropriately for the task demands are a matter of active debate. We used transcranial magnetic stimulation over the primary motor cortex to show that the excitability of the corticospinal tract is modulated to compensate for limb dynamics during reaching tasks in humans. Surprisingly, few profiles of corticospinal modulation in some muscles and conditions reflected Newtonian parameters of movement, such as kinematics or active torques. Instead, the overall corticospinal excitability was differentially modulated in proximal and distal muscles, which corresponded to different stiffness at proximal and distal joints. This suggests that the descending corticospinal signal determines the proximal and distal impedance of the arm for independent functional control of reaching and grasping.Significance StatementThe nervous system integrates both the physical properties of the human body and the environment to create a rich repertoire of actions. How these calculations are happening remains poorly understood. Neural activity is known to be correlated with different variables from the Newtonian equations of motion that describe forces acting on the body. In contrast, our data show that the overall activity of the descending neural signals is less related to the individual Newtonian variables and more related to limb impedance. We show that the physical properties of the arm are controlled by two distinct proximal and distal descending neural signals modulating components of limb stiffness. This identifies distinct neural control mechanisms for the transport and manipulation actions of reach.

scholarly journals Analysis of transcriptional regulation underlying central neural control mechanisms in acute hypertension

2007 ◽  
Vol 21 (5) ◽  
Author(s):  
Rajanikanth Vadigepalli ◽  
Rishi L Khan ◽  
Mary K McDonald ◽  
James S Schwaber
Keyword(s):  
Transcriptional Regulation ◽  
Neural Control ◽  
Control Mechanisms ◽  
Acute Hypertension

scholarly journals Regulat ory T-cells in periphera l blood of pat ientswith br onchial ast hma

2011 ◽  
Vol 8 (5) ◽  
pp. 21-25
Author(s):  
E E Kremer ◽  
N A Kirillova ◽  
N V Teplova ◽  
I A Deev ◽  
I V Petrova ◽  
...  
Keyword(s):  
T Cells ◽  
Peripheral Blood ◽  
Allergic Inflammation ◽  
Scientific Data ◽  
Control Mechanisms ◽  
Phenotypic Characteristics ◽  
Becton Dickinson ◽  
Surface Molecules ◽  
Healthy Donors ◽  
Healthy Control

Background. To investigate the expression of surface molecules CD4+CD25high and CD4+FoxP3+ on regulatory T-cells (Treg) in patients with different severity of bronchial asthma (BA). Methods. We included 19 patients with severe BA, 12 patients with mild BA and 17 healthy donors. The circulating percentage of CD4+CD25high and CD4+FoxP3+ T-reg in peripheral blood was estimated by the flow cytometry analysis (FACSCalibur, Becton Dickinson, USA). Results. Numbers of peripheral blood CD4+CD25high was significantly decreased in mild BA compared to healthy control. Patients with severe BA had increased levels of CD4+FoxP3+ and CD4+CD25high compared to mild BA. Conclusion. Our results demonstrate new scientific data on the phenotypic characteristics and the level of T-reg in peripheral blood at different clinical forms of asthma. This fact confirms the existence of immunoregulatory control mechanisms of allergic inflammation involving T-reg.

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