scholarly journals Low vision impairs implicit sensorimotor adaptation in response to small errors, but not large errors

2022 ◽  
Author(s):  
Jonathan S Tsay ◽  
Steven Tan ◽  
Marlena Chu ◽  
Richard B Ivry ◽  
Emily A Cooper
Keyword(s):  
Low Vision ◽  
The Body ◽  
Fine Tuning ◽  
Learning Deficits ◽  
Adaptive Process ◽  
Visuomotor Tasks ◽  
Size Interaction ◽  
Clinical Conditions ◽  
Sensory Uncertainty ◽  
New Hypothesis

Successful goal-directed actions require constant fine-tuning in response to errors introduced by changes in the body and environment. This implicit adaptive process has been assumed to operate in a statistically optimal fashion, reducing its sensitivity to errors when sensory uncertainty is high. However, recent work has shown that visual uncertainty attenuates implicit adaptation for small errors, but not large errors, a result that is at odds with an optimal integration hypothesis. This error size interaction has motivated a new hypothesis that sensory uncertainty impacts the distribution of the perceived error locations but not the system's sensitivity to errors. To examine these competing hypotheses, previous studies have experimentally manipulated uncertainty. But it is unknown which hypothesis best describes motor adaptation to sensory uncertainty experienced during daily life. To address this question, we recruited individuals with low vision due to diverse clinical conditions impacting visual uncertainty and matched controls. The groups were tested on visuomotor tasks designed to isolate implicit adaptation and maintain tight control over the error size. In two experiments, low vision was associated with attenuated implicit adaptation only for small errors, but not for large errors. Taken together with prior work in which visual uncertainty was experimentally manipulated, these results support the notion that increasing sensory uncertainty increases the likelihood that errors are mis-localized but does not affect error sensitivity, offering a novel account for the motor learning deficits seen in low vision.

Nervous Control of Chromatophores in Teleost Fishes

1964 ◽  
Vol 41 (3) ◽  
pp. 543-552
Author(s):  
J. D. PYE
Keyword(s):  
Local Heating ◽  
Respiratory Rhythm ◽  
Cellular Responses ◽  
The Body ◽  
Adaptive Responses ◽  
Physiological Mechanisms ◽  
Nervous Control ◽  
Temperature Thresholds ◽  
Motor Tracts ◽  
New Hypothesis

1. Observations of earlier workers on the chromatic responses to local heating or cooling of the skin of Phoxinus have been confirmed. They have also been found to hold true for anaesthetized fish, in which finer control and observation are possible. 2. The results of a series of nerve-section experiments are held to exclude any possibility that the responses of the intact fish are mediated by a nervous reflex from thermoreceptors in the skin. 3. The responses of melanophores following section of the chromatic motor tracts, or when isolated from the body, are considered to be independent cellular responses. 4. Normal responses in the intact fish show clear temperature thresholds and are completely dependent upon continuation of the respiratory rhythm. 5. Possible physiological mechanisms for mediating these non-adaptive responses are discussed and a new hypothesis is put forward.

scholarly journals Splenic Mechanisms of Thrombocytopenia

Blood ◽  
2017 ◽  
Vol 130 (Suppl_1) ◽  
pp. SCI-33-SCI-33
Author(s):  
John W. Semple
Keyword(s):  
Immune Responses ◽  
Reticuloendothelial System ◽  
Lymphoid Organ ◽  
The Body ◽  
White Pulp ◽  
Cellular Mechanisms ◽  
Venous Circulation ◽  
Destructive Processes ◽  
Clinical Conditions ◽  
Red Pulp

The spleen is the largest secondary lymphoid organ in the body and contains up to 25 percent of the body's lymphocyte populations. It is not only responsible for initiating immune responses against a multitude of infectious antigens within its white pulp, it also has the exquisite ability to filter the blood and remove, for example, senescent erythrocytes and platelets. This natural process is carried out within the red pulp of the spleen which is composed monocyte-rich connective tissue cords of Billroth intertwined with sinus cavities lined by parallel-oriented endothelial cells that have interendothelial slits which allow for the mechanical sorting of "old" cells. This occurs because of the inability of the senescent cells to properly migrate through the endothelial fenestrae into the venous circulation allowing them to be identified by cells of the reticuloendothelial system (RES) and quickly destroyed by phagocytosis. This process also allows for the efficient recycling of iron from destroyed erythrocyte hemoglobin molecules. There are a wide variety of clinical conditions that can significantly alter the ability of the RES to destroy blood cells including hereditary blood cell defects, inflammation, cancer and abnormal immune responses. This lecture will focus on the central role that the spleen plays in not only generating immune responses against platelets but also in primarily causing the destruction of both senescent and antibody-opsonized platelets leading to thrombocytopenia. It will discuss the soluble and cellular mechanisms of splenic sequestration, destruction and the ability of the spleen to modulate anti-platelet immunity. Mechanisms involving complement activation, Fc Receptor-mediated phagocytosis, antibody dependent cellular cytotoxicity and platelet self-destruction will be addressed. It will compare the spleen's platelet destructive capabilities with other organs, particularly the liver and will detail how immune responses generated in the white pulp can modulate platelet destructive processes in the red pulp. Disclosures Semple: Amgen: Consultancy, Honoraria, Speakers Bureau; Rigel: Consultancy, Honoraria; UCB: Consultancy, Honoraria.

scholarly journals Latent Factors Limiting the Performance of sEMG-Interfaces

2018 ◽  
Author(s):  
Sergey Lobov ◽  
Nadia Krilova ◽  
Innokentiy Kastalskiy ◽  
Victor Kazantsev ◽  
Valeri A. Makarov
Keyword(s):  
The Body ◽  
Fine Tuning ◽  
Fatty Tissue ◽  
Latent Factors ◽  
Individual Subject ◽  
Training Strategy ◽  
Real Time Analysis ◽  
Signal Processing Algorithms ◽  
Gaming Environment

Recent advances in recording and real-time analysis of surface electromyographic signals (sEMG) have fostered the use of sEMG human-machine interfaces for controlling personal computers, prostheses of upper limbs, and exoskeletons among others. Despite a relatively high mean performance, sEMG-interfaces still exhibit strong variance in the fidelity of gesture recognition among different users. Here we systematically study the latent factors determining the performance of sEMG-interfaces in synthetic tests and in an arcade game. We show that the degree of muscle cooperation and the amount of the body fatty tissue are the decisive factors in synthetic tests. Our data suggest that these factors can only be adjusted by a long-term training, which promotes fine-tuning of low-level neural circuits driving the muscles. A short-term training has no effect on synthetic tests, but significantly increases the game scoring. This implies that it works at a higher decision-making level, not relevant for synthetic gestures. We propose a procedure that enables quantification of the gestures’ fidelity in a dynamic gaming environment. For each individual subject the approach allows identifying “problematic” gestures that decrease gaming performance. This information can be used for optimizing the training strategy and for adapting the signal processing algorithms to individual users, which could be a way for a qualitative leap in the development of future sEMG-interfaces.

Heart failure: update on treatment and prognosis

2001 ◽  
Vol 10 (4) ◽  
pp. 285-293 ◽  
Author(s):  
LG Futterman ◽  
L Lemberg
Keyword(s):  
Beta Blockers ◽  
Left Ventricular ◽  
The Body ◽  
Fine Tuning ◽  
Significant Advance ◽  
Aldosterone Antagonists ◽  
Exercise Regimen ◽  
Hemodynamic Deterioration ◽  
Common Diagnosis ◽  
End Stage

HF is a prevalent and debilitating disease, affecting nearly 5 million patients and perhaps an equal number with asymptomatic left ventricular dysfunction who are at high risk of atrial fibrillation developing. An estimated 550,000 new cases occur every year. HF is the most common diagnosis in hospitalized patients aged 65 and over and is a major cause of death. The median survival after onset is 1.7 years in men and 3.2 years in women. The majority of cardiac deaths in patients with HF are sudden and arrhythmogenic: the rest are due to progressive hemodynamic deterioration. A significant advance in the past decade has been the recognition of the importance of inhibiting the neurohormonal action in HF with the use of beta-blockers, angiotensin receptor, and aldosterone antagonists. In addition, a new concept in HF therapy has evolved. The view that chronic HF is an irreversible, end-stage process is being supplanted by the fact that it is possible to effect biological improvement in the intrinsic defects of function and structure in hearts afflicted with chronic HF. Reversibility of HF has been reported by (1) unloading the failing heart using an LVAD, (2) the sophisticated use of diuretic combinations and neurohormonal blocking drugs, or (3) employing continuous arteriovenous hemofiltration. Thus it is now possible to reverse a process that has long been considered irreversible. Exercise programs designed for patients with HF that have been advocated recently can be difficult to apply. Fine tuning of an exercise regimen is required because a reduction in cardiac work is mandatory when treating HF, where the concern is that the heart may not be capable of supplying the metabolic needs of the body, even in resting states. Finally, although not emphasized in the recent literature on HF, the use of diuretics and sodium restriction continue to be the mainstays of therapy without which compensation of HF is not possible.

scholarly journals Equilibrium disorders in elderly: diagnostic classification and differential diagnosis

2013 ◽  
pp. 16-22
Author(s):  
Alessandro Castiglione ◽  
Claudia Aimoni ◽  
Giovanni Scanelli
Keyword(s):  
Differential Diagnosis ◽  
Elderly Patients ◽  
Neurological Disorders ◽  
Sensory Input ◽  
Neurological Diseases ◽  
Specific Treatment ◽  
The Body ◽  
Diagnostic Classification ◽  
Main Challenge ◽  
Clinical Conditions

Background: Balance is primarily related to the proper functioning of three sensory input: vestibular, visual and proprioceptive. The integration of these different afferences contributes to the proper attitude of the body in static and dynamic conditions. Equilibrium disorders are common among elderly patients and are responsible for falls and fractures, leading sometimes to catastrophic outcomes, representing a serious health and social problem. Approximately one third of elderly patients at home and about 50% of institutionalized, over 75 year-old, suffer from this particular condition, with at least one fall a year and almost 50% of these with recurrent episodes. Females are more affected than males. Attempts to ascertain the underlying cause of unbalance should be done, leading then to specific treatment. Nevertheless, many elderly patients do not have a single disease but rather a multitude of medical conditions which may cause dizziness, imbalance and vertigo: effects of ageing, drugs, cardiovascular and neurological disorders, ocular and orthopaedic diseases. Aim of the study: A literature review was carried out with the intention to offer practical and useful notions for the management and treatment of equilibrium disorders. Discussion: In clinical practice, the main challenge is to distinguish between peripheral and central imbalance disorders. The data collected from history and clinical exams should be integrated with the intent to include the patient in one of the following clinical conditions: vertiginous syndrome, pre-syncope and/or syncope, neurological diseases, other conditions.Conclusions: Following the differential diagnosis, treatment mainly consists in drug administration (antiemetic and vestibular suppressor drugs) and vestibular rehabilitation (physiotherapy and vestibular exercises).

scholarly journals RADIOACTIVE IRON ABSORPTION IN CLINICAL CONDITIONS: NORMAL, PREGNANCY, ANEMIA, AND HEMOCHROMATOSIS

1942 ◽  
Vol 76 (1) ◽  
pp. 15-30 ◽  
Author(s):  
W. M. Balfour ◽  
P. F. Hahn ◽  
W. F. Bale ◽  
W. T. Pommerenke ◽  
G. H. Whipple
Keyword(s):  
Iron Absorption ◽  
Normal Pregnancy ◽  
The Body ◽  
Human Beings ◽  
Chronic Infections ◽  
Red Marrow ◽  
Absorption Studies ◽  
Normal Absorption ◽  
Normal Human ◽  
Clinical Conditions

Radio iron is a tool which makes iron absorption studies quite accurate in dogs and reasonably satisfactory in human beings. This method is vastly superior to others previously used. Normal human pregnancy without significant anemia may show active radio iron absorption—16 to 27 per cent of iron intake. The pregnant woman as a rule shows 2 to 10 times the normal absorption of radio iron. Diseased states in which iron stores are known to be very abundant—pernicious anemia, hemochromatosis, familial icterus, and Mediterranean anemia —show very little absorption, probably less than normal. This is in spite of a severe anemia in all conditions except hemochromatosis. Chronic infections in spite of anemia show no utilization of radio iron, whether it may be absorbed or not. Leukemia shows little utilization of radio iron in red cells in spite of absorption (autopsy), probably because of white cells choking the red marrow. Polycythemia shows very low values for iron absorption as do normal persons. Two pregnant women showed only normal iron absorption. We believe that reserve stores of iron in the body, rather than anemia, control iron absorption. This control is exerted upon the gastro-intestinal mucosa which can refuse or accept iron under various conditions.

scholarly journals DNA methylation in the gene body influences MeCP2-mediated gene repression

2016 ◽  
Vol 113 (52) ◽  
pp. 15114-15119 ◽  
Author(s):  
Benyam Kinde ◽  
Dennis Y. Wu ◽  
Michael E. Greenberg ◽  
Harrison W. Gabel
Keyword(s):  
Gene Expression ◽  
Binding Protein ◽  
Neurodevelopmental Disorder ◽  
Transcriptional Repressor ◽  
The Body ◽  
Fine Tuning ◽  
Gene Repression ◽  
Gene Body ◽  
Primary Driver ◽  
Gene Expression Studies

Rett syndrome is a severe neurodevelopmental disorder caused by mutations in the methyl-CpG binding protein gene (MECP2). MeCP2 is a methyl-cytosine binding protein that is proposed to function as a transcriptional repressor. However, multiple gene expression studies comparing wild-type and MeCP2-deficient neurons have failed to identify gene expression changes consistent with loss of a classical transcriptional repressor. Recent work suggests that one function of MeCP2 in neurons is to temper the expression of the longest genes in the genome by binding to methylated CA dinucleotides (mCA) within transcribed regions of these genes. Here we explore the mechanism of mCA and MeCP2 in fine tuning the expression of long genes. We find that mCA is not only highly enriched within the body of genes normally repressed by MeCP2, but also enriched within extended megabase-scale regions surrounding MeCP2-repressed genes. Whereas enrichment of mCA exists in a broad region around these genes, mCA together with mCG within gene bodies appears to be the primary driver of gene repression by MeCP2. Disruption of methylation at CA sites within the brain results in depletion of MeCP2 across genes that normally contain a high density of gene-body mCA. We further find that the degree of gene repression by MeCP2 is proportional to the total number of methylated cytosine MeCP2 binding sites across the body of a gene. These findings suggest a model in which MeCP2 tunes gene expression in neurons by binding within the transcribed regions of genes to impede the elongation of RNA polymerase.

scholarly journals Neuroimmune Interactions: From the Brain to the Immune System and Vice Versa

2018 ◽  
Vol 98 (1) ◽  
pp. 477-504 ◽  
Author(s):  
Robert Dantzer
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Immune System ◽  
Long Range ◽  
Immune Cells ◽  
Short Range ◽  
The Body ◽  
Fine Tuning ◽  
Brain Functions ◽  
The Central Nervous System

Because of the compartmentalization of disciplines that shaped the academic landscape of biology and biomedical sciences in the past, physiological systems have long been studied in isolation from each other. This has particularly been the case for the immune system. As a consequence of its ties with pathology and microbiology, immunology as a discipline has largely grown independently of physiology. Accordingly, it has taken a long time for immunologists to accept the concept that the immune system is not self-regulated but functions in close association with the nervous system. These associations are present at different levels of organization. At the local level, there is clear evidence for the production and use of immune factors by the central nervous system and for the production and use of neuroendocrine mediators by the immune system. Short-range interactions between immune cells and peripheral nerve endings innervating immune organs allow the immune system to recruit local neuronal elements for fine tuning of the immune response. Reciprocally, immune cells and mediators play a regulatory role in the nervous system and participate in the elimination and plasticity of synapses during development as well as in synaptic plasticity at adulthood. At the whole organism level, long-range interactions between immune cells and the central nervous system allow the immune system to engage the rest of the body in the fight against infection from pathogenic microorganisms and permit the nervous system to regulate immune functioning. Alterations in communication pathways between the immune system and the nervous system can account for many pathological conditions that were initially attributed to strict organ dysfunction. This applies in particular to psychiatric disorders and several immune-mediated diseases. This review will show how our understanding of this balance between long-range and short-range interactions between the immune system and the central nervous system has evolved over time, since the first demonstrations of immune influences on brain functions. The necessary complementarity of these two modes of communication will then be discussed. Finally, a few examples will illustrate how dysfunction in these communication pathways results in what was formerly considered in psychiatry and immunology to be strict organ pathologies.

scholarly journals Change in homeostasis of the body and the outcome of tuberculosis in the treatment of antituberculous medicines

2018 ◽  
Vol 20 (3) ◽  
pp. 95-99
Author(s):  
A I Loshakova ◽  
N V Tsygan ◽  
S G Zheleznyak ◽  
N A Brazhenko ◽  
O N Brazhenko
Keyword(s):  
The State ◽  
The Body ◽  
Physical Factors ◽  
Daily Work ◽  
Role Of The State ◽  
Proliferation And Differentiation ◽  
Fundamental Research ◽  
Clinical Conditions ◽  
Medical University ◽  
Adaptive Reactions

Fundamental research in the field of physiology revealed the important role of the state of homeostatic balance of the body in the emergence, development and outcome of human diseases, including granulomatous respiratory diseases- tuberculosis and sarcoidosis. To assess the homeostasis of the body in clinical conditions, various research methods are used - immunological, biochemical, hormonal and functional. However, in the daily work they can’t always be performed for technical and economic reasons. Proposed a new available diagnostics criterion of homeostasis based on the study of the quantitative and qualitative characteristics of the leukocytic formula of peripheral blood at the Department of videopornonoelia the First St. Petersburg state medical University Academy I. P. Pavlov. Among them types of adaptive reactions, leukocyte- lymphocytic index, entropy and redundancy of indicators of leukogram, monitorama blood, the degree of homeostasis and types of reactivity of an organism. During their approbation in the clinic high information content was revealed: more than 70% of the examined patients with tuberculosis of respiratory organs had defective types of adaptive reactions (intense), indices of proliferation and differentiation of monocytes were changed, and reactivity of the organism was characterized by pathological types (hyperreactive, paradoxical, hyporeactive and areactive). Treatment of patients with anti-tuberculosis drugs partially improved homeostasis, but its full recovery at the end of the main course of treatment did not occur. For better treatment in complex therapy, it is necessary to activate the body’s protective systems with the use of adaptogens (drugs, medicinal plants, physical factors: ultrasound, ultra-high-frequency inductothermy, alternating magnetic field on the regulatory centers of the suprasegmental apparatus of the autonomic nervous system). Monitoring of the state of homeostasis is most convenient to carry out using the proposed new available criteria for its evaluation.

scholarly journals Features of diagnostics and surgical treatment of right ventricular thrombosis complicated by pulmonary artery thromboembolism (clinical case)

2019 ◽  
pp. 67-71
Author(s):  
R. M. Vitovsky ◽  
P. M. Semeniv ◽  
A. O. Rusnak ◽  
Y. R. Ivanov ◽  
V. F. Onischenko
Keyword(s):  
Pulmonary Embolism ◽  
Surgical Treatment ◽  
Pulmonary Artery ◽  
Right Ventricle ◽  
Right Ventricular ◽  
Young Patients ◽  
The Body ◽  
Blood Clots ◽  
The Right ◽  
Clinical Conditions

The case of differential diagnosis and treatment of a patient with pulmonary embolism (PE), the source of which was the thrombus formed in the right ventricle of the heart, is presented. The peculiarity of this case was the untimely diagnosis of the disease, which simulated pneumonia, the treatment of which did not improve the clinical condition of the patient. Tomography allowed to determine the thrombosis of the right branch of the pulmonary artery and to send the patient to the cardiac surgery center for further treatment. Diagnosis of a probable source of embolism occurred after echocardiography, which revealed a tumor-like lesion of the right ventricle of large size and dense consistency. The results of surgical treatment of the patient, during which extensive formation of the right ventricle was removed, a dense elastic consistency with signs of fragmentation confirmed the prediction of this particular source of pulmonary embolism. Removal of blood clots from the right branch of the pulmonary embolism showed their similar macrostructure with right ventricular formation. The appearance and macrostructure of the formation did not allow to determine with certainty its character. Only histological examination was able to determine the thrombogenicity of the origin of this formation. The recurrent nature of pneumonia, without the presence of risk factors, in young patients may be the basis for more thorough examination to identify atypical clinical conditions. The restoration of the source of the body is of great importancefor the prevention of its relapse. Finding the source of pulmonary embolism should necessarily include echocardiography to carefully examine possible lesions of intracardiac structures with the formation of blood clots that may be responsible for its occurrence.

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