HUMAN REFLEXIVE RESPONSE AND ITS OBJECTIVE FUNCTION REGARDING BALANCE RECOVERY FROM PERTURBATION DURING WALKING

2011 ◽  
Vol 11 (05) ◽  
pp. 1179-1198 ◽  
Author(s):  
YU YIKEMOTO ◽  
WENWEI YU ◽  
U. RAJENDRA ACHARYA
Keyword(s):  
Underlying Mechanism ◽  
Living Environment ◽  
Neural Mechanisms ◽  
Unified Theory ◽  
Response Patterns ◽  
Objective Functions ◽  
Balance Recovery ◽  
Uneven Terrain ◽  
Short Period ◽  
Evaluation Measure

Balance recovery from perturbation plays a crucial role in preventing people from falling during walking. Understanding the underlying mechanism of balance recovery during walking could not only bring new insights into the motor control field, but also benefit the development of walking assist systems for daily living environment, where perturbations to walking are frequently caused by slips, uneven terrain, slopes, obstacles, etc.It is evident that humans can cope with such perturbations, especially when the perturbations cannot be predicted or perceived in advance, by means of reflexes, which cause relatively fixed, unconscious muscular response patterns to perturbations within a short period of time ranging from several tens of ms to 200 ms. However, except for several hypotheses about the underlying neural mechanisms of the reflexes during walking, there is no widely accepted unified theory.In our previous study, a muscular-reflexive pattern was defined using muscle activity recorded during reflexive responses to slip perturbation. This is one important step toward the understanding of the underlying mechanism, since the pattern could serve as the quantitative target in pursuit of the underlying mechanism. We can speculate that this pattern is the optimal balance recovery behavior to human muscular-skeletal system, as a result of long evolution; however, before we use this target to guide our pursuit, we should first prove its optimality, while making clear the objective functions for balance recovery and the effect of morphological factors.Our approach includes (1) defining objective functions for balance recovery from a slip perturbation during walking; (2) using a bio-mimetic human walking simulator to perform evaluation according to the objective functions; (3) employing a genetic algorithm (GA) to search the optimal solutions, for different objective functions.Results showed that the muscular-reflexive pattern is optimal to the balance recovery from slip perturbation during walking, in terms of a hybrid evaluation measure (HEM), which takes both static and dynamic aspects of balance recovery into consideration.

scholarly journals The Roles of CPG Phase Modulation and Reflexive Muscular Patterns in Balance Recovery During Walking—A Simulation Study

2008 ◽  
Vol 5 (1) ◽  
pp. 1-11
Author(s):  
Yu Ikemoto ◽  
Wenwei Yu
Keyword(s):  
Motor Control ◽  
Simulation Study ◽  
Real World ◽  
Phase Modulation ◽  
Response Patterns ◽  
Stability Criteria ◽  
Simulation Experiments ◽  
Uneven Terrain ◽  
Short Period ◽  
Muscle Responses

Most walking assist systems reported are not available for real world environments where frequent perturbations are caused by slips, uneven terrain, slopes and obstacles. It is evident that humans are able to cope with such perturbations with reflexes that cause unconscious, relatively fixed muscular response patterns to perturbations within a short period of time. In our previous study, we showed that artificial reflexes could improve the perturbation resistance for simulated walkers, though the roles of different reflexive mechanisms were not quantitatively clarified. In this study, we focused on the different roles of reflexive muscle responses and the CPG phase modulation mechanism. By proposing and evaluating two stability criteria through a series of simulation experiments, we revealed different roles for two mechanisms in the simulated walkers. These will not only further increase the possibility of realising artificial reflexes for paralysed individuals, but also bring new insights into the field of motor control.

scholarly journals Superimposed gratings induce diverse response patterns of gamma oscillations in primary visual cortex

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bin Wang ◽  
Chuanliang Han ◽  
Tian Wang ◽  
Weifeng Dai ◽  
Yang Li ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Field Potential ◽  
Gamma Oscillations ◽  
Neural Mechanisms ◽  
Model Parameters ◽  
Response Patterns ◽  
Region Difference ◽  
High Gamma ◽  
Spiking Activity

AbstractStimulus-dependence of gamma oscillations (GAMMA, 30–90 Hz) has not been fully understood, but it is important for revealing neural mechanisms and functions of GAMMA. Here, we recorded spiking activity (MUA) and the local field potential (LFP), driven by a variety of plaids (generated by two superimposed gratings orthogonal to each other and with different contrast combinations), in the primary visual cortex of anesthetized cats. We found two distinct narrow-band GAMMAs in the LFPs and a variety of response patterns to plaids. Similar to MUA, most response patterns showed that the second grating suppressed GAMMAs driven by the first one. However, there is only a weak site-by-site correlation between cross-orientation interactions in GAMMAs and those in MUAs. We developed a normalization model that could unify the response patterns of both GAMMAs and MUAs. Interestingly, compared with MUAs, the GAMMAs demonstrated a wider range of model parameters and more diverse response patterns to plaids. Further analysis revealed that normalization parameters for high GAMMA, but not those for low GAMMA, were significantly correlated with the discrepancy of spatial frequency between stimulus and sites’ preferences. Consistent with these findings, normalization parameters and diversity of high GAMMA exhibited a clear transition trend and region difference between area 17 to 18. Our results show that GAMMAs are also regulated in the form of normalization, but that the neural mechanisms for these normalizations might differ from those of spiking activity. Normalizations in different brain signals could be due to interactions of excitation and inhibitions at multiple stages in the visual system.

scholarly journals The Wuhan Pneumonia Outbreak: High Isoleucine and High Valine Plus Glycine Contents Are Features of the Proteins of 2019-nCoV Virus

2020 ◽  
Author(s):  
Sirui Yan ◽  
Yulin Wan ◽  
Ying Zhang ◽  
Shanshan An ◽  
Kaiqiao Yang ◽  
...  
Keyword(s):  
Amino Acids ◽  
Animal Studies ◽  
Viral Infections ◽  
Underlying Mechanism ◽  
Essential Amino Acids ◽  
Global Scale ◽  
Open Reading Frame ◽  
Cell Swelling ◽  
Reading Frame ◽  
Short Period

The current pneumonia epidemic in China could evolve into a pandemic on a global scale if not effectively contained. The 2019-nCoV possesses a 61-amino acid open reading frame resembling SARS-CoV virulence factor - ORF6 peptide. The isoleucine content is 15.9% in ORF6 of SARS-CoV versus 16.4% of that in 2019-nCoV. Given the proton affinity in the carbonyl oxygen in isoleucine, augmented proton traffic can enhance proton-ion antiport and prompt cell swelling. As the content of essential amino acids in the open reading frame of 2019-nCoV reaches 57.4%, a starch/vitamin diet served for short period of time does not give rise to essential amino acids and halts virion production, which could be adopted as prophylactic approach of many viral infections. Plant-based diet or fasting/boiled rice water can also minimize the intake of essential amino acids or all amino acids respectively. Calorie restriction has been confirmed in animal studies to extend lifespan, and its underlying mechanism is not fully known. Furthermore, several proteins of 2019-nCoV possess high valine plus glycine content, which is implicated in heart disease.

Neural mechanisms of sneeze

1975 ◽  
Vol 229 (3) ◽  
pp. 770-776 ◽  
Author(s):  
HL Batsel ◽  
AJ Lines
Keyword(s):  
High Frequency ◽  
Neural Mechanisms ◽  
Nucleus Ambiguus ◽  
Respiratory Neurons ◽  
Similar Response ◽  
Response Patterns ◽  
Nerve Activity ◽  
Inspiratory Neurons ◽  
Expiratory Neurons ◽  
Stimulation Of

Sneezes were induced in anestized cats by repetitive stimulation of the ethmoidal nerve. Activity of bulbar respiratory neurons during sneezing was recorded extracellularly through tungsten microelectrodes. Most expiratory neurons could be locked onto the stimulus pulses so that they responded either throughout inspiration as well as expiration or so that they began responding at some time during inspiration. As inspiration approached termination, multiple spiking occurred, finally to result in high-frequency bursts which just preceded active expiration. A fraction of expiratory neurons were activated only in bursts. Latent expiratory neurons were recruited in sneezing. Inspiratory neurons near nucleus ambiguus and most of those near fasciculus solitarius displayed similar response patterns consisting of silent periods followed by delayed smooth activations. Temporal characteristics of the silent periods, "inhibitory gaps," suggested that they resulted from inhibition whose source was the expiratory neurons which were driven throughout inspriation. Some inspiratory neurons in the area of fasciculus solitarius failed to exhibit inhibitory gaps.

Modeling Neural Mechanisms for Genesis of Respiratory Rhythm and Pattern. III. Comparison of Model Performances During Afferent Nerve Stimulation

1997 ◽  
Vol 77 (4) ◽  
pp. 2027-2039 ◽  
Author(s):  
Ilya A. Rybak ◽  
Julian F. R. Paton ◽  
James S. Schwaber
Keyword(s):  
Experimental Data ◽  
Short Duration ◽  
Nerve Stimulation ◽  
Vagal Stimulation ◽  
Respiratory Rhythm ◽  
Neural Mechanisms ◽  
Afferent Nerve ◽  
Respiratory Pattern ◽  
Expiratory Phase ◽  
Short Period

Rybak, Ilya A., Julian F. R. Paton, and James S. Schwaber. Modeling neural mechanisms for genesis of respiratory rhythm and pattern. III. Comparison of model performances during afferent nerve stimulation. J. Neurophysiol. 77: 2027–2039, 1997. The goal of the present study was to evaluate the relative plausibility of the models of the central respiratory pattern generator (CRPG) proposed in our previous paper. To test the models, we compared changes in generated patterns with the experimentally observed alterations of the respiratory pattern induced by various stimuli applied to superior laryngeal (SLN), vagus and carotid sinus (CS) nerves. In all models, short-duration SLN simulation caused phase-resetting behavior consistent with experimental data. Relatively weak sustained SLN stimulation elicited a two-phase rhythm comprising inspiration and postinspiration whereas a stronger stimulation stopped oscillations in the postinspiratory phase (“postinspiratory apnea”). In all models, sustained vagus nerve stimulation produced postinspiratory apnea. A short vagal stimulus delivered during inspiration terminated this phase. The threshold for inspiratory termination decreased during the course of the inspiratory phase. The effects of short-duration vagal stimulation applied during expiration were different in different models. In model 1, stimuli delivered in the postinspiratory phase prolonged expiration whereas the late expiratory phase was insensitive to vagal stimulation. No insensitive period was found in model 2 because vagal stimuli delivered at any time during expiration prolonged this phase. Model 3 demonstrated a short period insensitive to vagal stimulation at the very end of expiration. When phasic CS nerve stimulation was applied during inspiration or the first half of expiration, the performances of all models were similar and consistent with experimental data: stimuli delivered at the beginning inspiration shortened this phase whereas stimuli applied in the middle or at the end of inspiration prolonged it and stimuli delivered in the first half of expiration prolonged the expiratory interval. Behavior of the models were different when CS stimuli were delivered during the late expiratory phase. In model 1, these stimuli were ineffective or shortened expiration initiating the next inspiration. Alternatively, in models 2 and 3, they caused a prolongation of expiration. Although all CRPG models demonstrated a number of plausible alterations in the respiratory pattern elicited by afferent nerve stimulation, the behavior of model 1 was most consistent with experimental data. Taking into account differences in the model architectures and employed neural mechanisms, we suggest that the concept of respiratory rhythmogenesis based on the essential role of postinspiratory neurons is more plausible than the concept employing specific functional properties of decrementing expiratory (dec-E) neurons and that the ramp firing pattern of the late expiratory neuron is more likely to reflect intrinsic properties than disinhibition from the dec-E neurons.

scholarly journals Vancomycin Acts Synergistically with Gentamicin against Penicillin-Resistant Pneumococci by Increasing the Intracellular Penetration of Gentamicin

2003 ◽  
Vol 47 (1) ◽  
pp. 144-147 ◽  
Author(s):  
P. Cottagnoud ◽  
M. Cottagnoud ◽  
M. G. Täuber
Keyword(s):  
Viable Cell ◽  
Underlying Mechanism ◽  
Intracellular Concentration ◽  
Combination Regimen ◽  
Cell Counts ◽  
Short Period ◽  
Before And After ◽  
Gentamicin Concentration

ABSTRACT Vancomycin and gentamicin act synergistically against penicillin-resistant pneumococci in vitro and in experimental rabbit meningitis. The aim of the present study was to investigate the underlying mechanism of this synergism. The intracellular concentration of gentamicin was measured by using the following experimental setting. Bacterial cultures were incubated with either gentamicin alone or gentamicin plus vancomycin for a short period (15 min). The gentamicin concentration was determined before and after grinding of the cultures by using the COBAS INTEGRA fluorescence polarization system (Roche). The grinding efficacies ranged between 44 and 54%, as determined by viable cell counts. In the combination regimen the intracellular concentration of gentamicin increased to 186% compared to that achieved with gentamicin monotherapy. These data suggest that the synergy observed in vivo and in vitro is based on an increased intracellular penetration of the aminoglycoside, probably due to the effect of vancomycin on the permeability of the cell wall.

scholarly journals Freezing: how do water mites (Acari: Hydrachnidia) survive exposure to sub-zero temperatures?

2021 ◽  
Author(s):  
Andrzej Zawal ◽  
Tomasz Czernicki ◽  
Grzegorz Michoński ◽  
Aleksandra Bańkowska ◽  
Robert Stryjecki ◽  
...  
Keyword(s):  
Survival Rate ◽  
Survival Rates ◽  
Living Environment ◽  
Individual Species ◽  
Water Mites ◽  
Climatic Zones ◽  
Long Period ◽  
Short Period ◽  
The Moment ◽  
The Impact

AbstractUntil now, very little is known about the ability of adult and deutonymph water mites (Acari, Hydrachnidia) to survive in sub-zero temperatures. Information concerns mainly water mites from vernal astatic waters, and the knowledge has never been experimentally verified. To determine the sensitivity of water mites to freezing, experiments were conducted on (1) the impact of acclimatization, (2) temperature, and (3) duration of freezing on survival, (4) the survival rate of water mites from various types of water bodies, and (5) the survival rate of water mites from different climatic zones. The experiments were carried out in a phytotron chamber, and water mites were placed in containers (10 × 10 × 5 cm) filled with 4/5 of water for 10 specimens each. Water mites were identified to the species level after finishing the experiments. The temperature was lowered 1 °C every hour until the target temperature was reached. After a certain period of freezing (depending on the treatment) the temperature was raised by 1 °C every hour until it reached 4 °C. The time of the experiment was measured from the moment the desired temperature was reached (below 0 °C) until the ice thawed and the temperature of 4 °C was reached again. The highest survival rates had Limnochares aquatica, Piona nodata, Sperchon clupeifer and Lebertia porosa, followed by L. insignis, Hygrobates longipalpis, H. setosus, Limnesia undulatoides, Piona pusilla, Arrenurus globator, Hydrodroma despiciens, Piona longipalpis, Sperchonopsis verrucosa, Unionicola crassipes and Mideopsis crassipes; no specimens of Torrenticola amplexa survived. The following conclusions were drawn: (1) water mites can survive freezing to −2 °C, lower temperatures are lethal for them; (2) they survived better the short period of freezing (24–48 h) than the long period (168 h); (3) resistance to freezing seems to be an evolutionary trait of individual species, only partly related to the living environment; and (4) freezing survival rates are linked to the region of Europe and are much lower in Southern than in Central Europe.

scholarly journals The Wuhan Pneumonia Outbreak: High Isoleucine and High Valine Plus Glycine Contents Are Features of the Proteins of 2019-nCoV Virus

2020 ◽  
Author(s):  
Sirui Yan ◽  
Yulin Wan ◽  
Ying Zhang ◽  
Shanshan An ◽  
Kaiqiao Yang ◽  
...  
Keyword(s):  
Amino Acids ◽  
Animal Studies ◽  
Viral Infections ◽  
Underlying Mechanism ◽  
Essential Amino Acids ◽  
Global Scale ◽  
Open Reading Frame ◽  
Cell Swelling ◽  
Reading Frame ◽  
Short Period

The current pneumonia epidemic in China could evolve into a pandemic on a global scale if not effectively contained. The 2019-nCoV possesses a 61-amino acid open reading frame resembling SARS-CoV virulence factor - ORF6 peptide. The isoleucine content is 15.9% in ORF6 of SARS-CoV versus 16.4% of that in 2019-nCoV. Given the proton affinity in the carbonyl oxygen in isoleucine, augmented proton traffic can enhance proton-ion antiport and prompt cell swelling. As the content of essential amino acids in the open reading frame of 2019-nCoV reaches 57.4%, a starch/vitamin diet served for short period of time does not give rise to essential amino acids and halts virion production, which could be adopted as prophylactic approach of many viral infections. Plant-based diet or fasting/boiled rice water can also minimize the intake of essential amino acids or all amino acids respectively. Calorie restriction has been confirmed in animal studies to extend lifespan, and its underlying mechanism is not fully known. Furthermore, several proteins of 2019-nCoV possess high valine plus glycine content, which is implicated in heart disease.

scholarly journals Quercetin Reduces Oxidative Stress and Apoptosis by Inhibiting HMGB1 and Its Translocation, Thereby Alleviating Liver Injury in ACLF Rats

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Peng Fang ◽  
Bo Dou ◽  
Jiajun Liang ◽  
Weixin Hou ◽  
Chongyang Ma ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Liver Injury ◽  
Liver Failure ◽  
High Mobility ◽  
Rat Hepatocytes ◽  
Underlying Mechanism ◽  
Chronic Liver ◽  
Liver Pathology ◽  
Short Period

Background. Acute on chronic liver failure (ACLF) is a syndrome of acute liver failure that occurs on the basis of chronic liver disease, which is characterized by a rapid deterioration in a short period and high mortality. High mobility group box 1 (HMGB1) may be involved in the pathological process of ACLF; its specific role remains to be further elucidated. Our previous studies have shown that quercetin (Que) exerts anti-oxidant and anti-apoptotic effects by inhibiting HMGB1 in vitro. The present study aimed to investigate the effect of Que on liver injury in ACLF rats. Methods. The contents of ALT, AST, TBiL, and PT time of rats in each group were observed. HE staining was used to detect liver pathology. The levels of oxidative stress indicators such as MDA, GSH, and 4-HNE in the rat liver were detected. TUNEL assay was used to detect apoptosis in rat hepatocytes. Immunofluorescence and western blot analysis were performed to explore the protective effect of Que on ACLF rats and the underlying mechanism. Results. The results showed that Que could reduce the increase of serum biochemical indices, improve liver pathology, and reduce liver damage in ACLF rats. Further results confirmed that Que reduced the occurrence of oxidative stress and apoptosis of hepatocytes, and these reactions may aggravate the progress of ACLF. Meanwhile, the results of immunofluorescence and western blotting also confirmed that the expression of HMGB1 and extranuclear translocation in ACLF rat hepatocytes were significantly increased, which was alleviated by the treatment of Que. In addition, when cotreated with glycyrrhizin (Gly), an inhibitor of HMGB1, the inhibition of Que on HMGB1 and its translocation, apoptosis and oxidative stress, and the related proteins of HMGB1-mediated cellular pathway have been significantly enhanced. Conclusion. Thus, Que alleviates liver injury in ACLF rats, and its mechanism may be related to oxidative stress and apoptosis caused by HMGB1 and its translocation.

OPTIMIZING FOOT CENTERS OF PRESSURE THROUGH FORCE DISTRIBUTION IN A HUMANOID ROBOT

2013 ◽  
Vol 10 (03) ◽  
pp. 1350027 ◽  
Author(s):  
PATRICK M. WENSING ◽  
GHASSAN BIN HAMMAM ◽  
BEHZAD DARIUSH ◽  
DAVID E. ORIN
Keyword(s):  
Contact Forces ◽  
Whole Body ◽  
Force Distribution ◽  
Objective Functions ◽  
Distribution Problem ◽  
Double Support ◽  
Uneven Terrain ◽  
Analytical Approaches ◽  
Convex Formulation

The force distribution problem (FDP) in robotics requires the determination of multiple contact forces to match a desired net contact wrench. For the double support case encountered in humanoids, this problem is underspecified, and provides the opportunity to optimize desired foot centers of pressure (CoPs) and forces. In different contexts, we may seek CoPs and contact forces that optimize actuator effort or decrease the tendency for foot roll. In this work, we present two formulations of the FDP for humanoids in double support, and propose objective functions within a general framework to address the variety of competing requirements for the realization of balance. As a key feature, the framework is capable to optimize contact forces for motions on uneven terrain. Solutions for the formulations developed are obtained with a commercial nonlinear optimization package and through analytical approaches on a simplified problem. Results are shown for a highly dynamic whole-body humanoid reaching motion performed on even terrain and on a ramp. A convex formulation of the FDP provides real-time solutions with computation times of a few milliseconds. While the convex formulation does not include CoPs explicitly as optimization variables, a novel objective function is developed which penalizes foot CoP solutions that approach the foot boundaries.

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