Understanding Human Neural Control of Short-term Gait Adaptation to the Split-belt Treadmill

Neuroscience ◽  
2020 ◽  
Vol 451 ◽  
pp. 36-50
Author(s):  
Dorelle C. Hinton ◽  
David Moulaee Conradsson ◽  
Caroline Paquette
Keyword(s):  
Neural Control ◽  
Short Term ◽  
Gait Adaptation

Blood volume redistribution from a passive elastic permeable microcirculation due to hypovolemia

1994 ◽  
Vol 266 (6) ◽  
pp. H2268-H2278
Author(s):  
A. J. LaForte ◽  
L. P. Lee ◽  
G. F. Rich ◽  
T. C. Skalak ◽  
J. S. Lee
Keyword(s):  
Blood Volume ◽  
Plasma Density ◽  
Neural Control ◽  
Circulation Model ◽  
Volume Of Fluid ◽  
Time Interval ◽  
Short Term ◽  
Local Regulation ◽  
Pentobarbital Sodium ◽  
Volume Shift

We measured the variations in blood and plasma density for a cyclic hemorrhage protocol in conscious rabbits to calculate delta Vf [the volume of fluid restituted into the circulation from the time the blood volume was at its control to that after the hemorrhage of a blood volume (delta V)] and delta Vs (the volume shift from micro- to macrocirculation over the same time interval). We found that delta Vf is 7% of delta V and delta Vs 60% of delta V. They combine to reduce the effect of hemorrhage on macrovascular volume by 67% of delta V. Based on a two-resistor circulation model, the change in microcirculatory pressure (delta Pmic) from control to hemorrhage was estimated from the measured cardiac outputs and arterial and venous pressures. The computations indicate that delta Vs (or delta Vf) is linearly related to delta Pmic. With one relation fitting all data of rabbits that were conscious, infused with hexamethonium, and anesthetized with pentobarbital sodium, we concluded that the two short-term volume redistributions are not direct neural control or local regulation, but the response of a passive, permeable microcirculation to delta Pmic. From the linear relations, we obtained 0.88 ml.mmHg-1.kg-1 as the compliance of the rabbit microcirculation and 0.21 ml.min-1.mmHg-1.kg-1 as its filtration coefficient.

PROLACTIN ACTIVITY OF SHORT-TERM AND LONG-TERM AUTOGRAFTED PITUITARIES OF THE HYPOPHYSECTOMIZED CRESTED NEWT

1969 ◽  
Vol 45 (4) ◽  
pp. 525-530 ◽  
Author(s):  
A. PEYROT ◽  
V. MAZZI ◽  
C. VELLANO ◽  
G. LODI
Keyword(s):  
Feedback Control ◽  
Neural Control ◽  
Short Term ◽  
Crested Newt

SUMMARY The transplanted pituitary is able to trigger water drive in estivating hypophysectomized adult newts up to 140 days after the operation. Both in short-term (30 days) and long-term (140 days) operated animals the grafted pituitary produced significantly more prolactin than in controls. The results indicate that in the estivating crested newt prolactin production is under an inhibitory neural control and that a short feedback control is not exerted by prolactin itself on the grafted pituitary.

scholarly journals An integrated mathematical model of the human cardiopulmonary system: model development

2016 ◽  
Vol 310 (7) ◽  
pp. H899-H921 ◽  
Author(s):  
Antonio Albanese ◽  
Limei Cheng ◽  
Mauro Ursino ◽  
Nicolas W. Chbat
Keyword(s):  
Neural Control ◽  
Model Development ◽  
Control Mechanisms ◽  
Short Term ◽  
Physiological Variables ◽  
Animal Data ◽  
Adult Humans ◽  
Underlying Mechanisms ◽  
Cardiopulmonary System ◽  
Alveolar Gas Exchange

Several cardiovascular and pulmonary models have been proposed in the last few decades. However, very few have addressed the interactions between these two systems. Our group has developed an integrated cardiopulmonary model (CP Model) that mathematically describes the interactions between the cardiovascular and respiratory systems, along with their main short-term control mechanisms. The model has been compared with human and animal data taken from published literature. Due to the volume of the work, the paper is divided in two parts. The present paper is on model development and normophysiology, whereas the second is on the model's validation on hypoxic and hypercapnic conditions. The CP Model incorporates cardiovascular circulation, respiratory mechanics, tissue and alveolar gas exchange, as well as short-term neural control mechanisms acting on both the cardiovascular and the respiratory functions. The model is able to simulate physiological variables typically observed in adult humans under normal and pathological conditions and to explain the underlying mechanisms and dynamics.

Modular Neural Control for Gait Adaptation and Obstacle Avoidance of a Tailless Gecko Robot

2021 ◽  
Vol 101 (2) ◽  
Author(s):  
Arthicha Srisuchinnawong ◽  
Bingcheng Wang ◽  
Donghao Shao ◽  
Potiwat Ngamkajornwiwat ◽  
Zhendong Dai ◽  
...  
Keyword(s):  
Obstacle Avoidance ◽  
Neural Control ◽  
Gait Adaptation

scholarly journals Assessment of Baroreflex Sensitivity Using Time-Frequency Analysis during Postural Change and Hypercapnia

2019 ◽  
Vol 2019 ◽  
pp. 1-17
Author(s):  
Agnieszka Kazimierska ◽  
Michał M. Placek ◽  
Agnieszka Uryga ◽  
Paweł Wachel ◽  
Małgorzata Burzyńska ◽  
...  
Keyword(s):  
Heart Rate ◽  
Neural Control ◽  
Baroreflex Sensitivity ◽  
Systolic Pressure ◽  
Pulse Interval ◽  
Postural Change ◽  
Short Term ◽  
Time Frequency ◽  
Arterial Blood ◽  
The Relationship

Baroreflex is a mechanism of short-term neural control responsible for maintaining stable levels of arterial blood pressure (ABP) in an ABP-heart rate negative feedback loop. Its function is assessed by baroreflex sensitivity (BRS)—a parameter which quantifies the relationship between changes in ABP and corresponding changes in heart rate (HR). The effect of postural change as well as the effect of changes in blood O2 and CO2 have been the focus of multiple previous studies on BRS. However, little is known about the influence of the combination of these two factors on dynamic baroreflex response. Furthermore, classical methods used for BRS assessment are based on the assumption of stationarity that may lead to unreliable results in the case of mostly nonstationary cardiovascular signals. Therefore, we aimed to investigate BRS during repeated transitions between squatting and standing in normal end-tidal CO2 (EtCO2) conditions (normocapnia) and conditions of progressively increasing EtCO2 with a decreasing level of O2 (hypercapnia with hypoxia) using joint time and frequency domain (TF) approach to BRS estimation that overcomes the limitation of classical methods. Noninvasive continuous measurements of ABP and EtCO2 were conducted in a group of 40 healthy young volunteers. The time course of BRS was estimated from TF representations of pulse interval variability and systolic pressure variability, their coherence, and phase spectra. The relationship between time-variant BRS and indices of ABP and HR was analyzed during postural change in normocapnia and hypercapnia with hypoxia. In normocapnia, observed trends in all measures were in accordance with previous studies, supporting the validity of presented TF method. Similar but slightly attenuated response to postural change was observed in hypercapnia with hypoxia. Our results show the merits of the nonstationary methods as a tool to study the cardiovascular system during short-term hemodynamic changes.

scholarly journals Gait parameter control timing with dynamic manual contact or visual cues

2016 ◽  
Vol 115 (6) ◽  
pp. 2880-2892 ◽  
Author(s):  
Ely Rabin ◽  
Peter Shi ◽  
William Werner
Keyword(s):  
Gait Speed ◽  
Neural Control ◽  
Gait Parameter ◽  
Tracking Accuracy ◽  
Step Cycle ◽  
Double Support ◽  
Gait Adaptation ◽  
Eyes Closed ◽  
Gait Parameters ◽  
Timing Pattern

We investigated the timing of gait parameter changes (stride length, peak toe velocity, and double-, single-support, and complete step duration) to control gait speed. Eleven healthy participants adjusted their gait speed on a treadmill to maintain a constant distance between them and a fore-aft oscillating cue (a place on a conveyor belt surface). The experimental design balanced conditions of cue modality (vision: eyes-open; manual contact: eyes-closed while touching the cue); treadmill speed (0.2, 0.4, 0.85, and 1.3 m/s); and cue motion (none, ±10 cm at 0.09, 0.11, and 0.18 Hz). Correlation analyses revealed a number of temporal relationships between gait parameters and cue speed. The results suggest that neural control ranged from feedforward to feedback. Specifically, step length preceded cue velocity during double-support duration suggesting anticipatory control. Peak toe velocity nearly coincided with its most-correlated cue velocity during single-support duration. The toe-off concluding step and double-support durations followed their most-correlated cue velocity, suggesting feedback control. Cue-tracking accuracy and cue velocity correlations with timing parameters were higher with the manual contact cue than visual cue. The cue/gait timing relationships generalized across cue modalities, albeit with greater delays of step-cycle events relative to manual contact cue velocity. We conclude that individual kinematic parameters of gait are controlled to achieve a desired velocity at different specific times during the gait cycle. The overall timing pattern of instantaneous cue velocities associated with different gait parameters is conserved across cues that afford different performance accuracies. This timing pattern may be temporally shifted to optimize control. Different cue/gait parameter latencies in our nonadaptation paradigm provide general-case evidence of the independent control of gait parameters previously demonstrated in gait adaptation paradigms.

Conceptual short-term memory (CSTM) supports core claims of Christiansen and Chater

2016 ◽  
Vol 39 ◽  
Author(s):  
Mary C. Potter
Keyword(s):  
Working Memory ◽  
Rapid Serial Visual Presentation ◽  
Language Comprehension ◽  
Short Term Memory ◽  
Visual Presentation ◽  
Long Term Memory ◽  
Short Term ◽  
Term Memory ◽  
Use Of Knowledge

AbstractRapid serial visual presentation (RSVP) of words or pictured scenes provides evidence for a large-capacity conceptual short-term memory (CSTM) that momentarily provides rich associated material from long-term memory, permitting rapid chunking (Potter 1993; 2009; 2012). In perception of scenes as well as language comprehension, we make use of knowledge that briefly exceeds the supposed limits of working memory.

Ultrastructural Changes of Canine Kidneys During 24-Hour Perfusion on a LI-400 Preservation System

1971 ◽  
Vol 29 ◽  
pp. 316-317
Author(s):  
M. O. Magnusson ◽  
D. G. Osborne ◽  
T. Shimoji ◽  
W. S. Kiser ◽  
W. A. Hawk
Keyword(s):  
Electron Microscopy ◽  
Electrolyte Solution ◽  
Ultrastructural Changes ◽  
Midline Incision ◽  
Short Term ◽  
Pentobarbital Anesthesia ◽  
Pulsatile Perfusion

Short term experimental and clinical preservation of kidneys is presently best accomplished by hypothermic continuous pulsatile perfusion with cryoprecipitated and millipore filtered plasma. This study was undertaken to observe ultrastructural changes occurring during 24-hour preservation using the above mentioned method.A kidney was removed through a midline incision from healthy mongrel dogs under pentobarbital anesthesia. The kidneys were flushed immediately after removal with chilled electrolyte solution and placed on a LI-400 preservation system and perfused at 8-10°C. Serial kidney biopsies were obtained at 0-½-1-2-4-8-16 and 24 hours of preservation. All biopsies were prepared for electron microscopy. At the end of the preservation period the kidneys were autografted.

Polychlorinated biphenyl induced hepatocyte alterations

1987 ◽  
Vol 45 ◽  
pp. 716-717
Author(s):  
D.N. Collins ◽  
J.N. Turner ◽  
K.O. Brosch ◽  
R.F. Seegal
Keyword(s):  
Lipid Droplets ◽  
Wistar Rats ◽  
Homovanillic Acid ◽  
Polychlorinated Biphenyl ◽  
Corn Oil ◽  
Environmental Pollutants ◽  
Short Term ◽  
Pcb Congeners ◽  
Urinary Levels ◽  
The Brain

Polychlorinated biphenyls (PCBs) are a ubiquitous class of environmental pollutants with toxic and hepatocellular effects, including accumulation of fat, proliferated smooth endoplasmic recticulum (SER), and concentric membrane arrays (CMAs) (1-3). The CMAs appear to be a membrane storage and degeneration organelle composed of a large number of concentric membrane layers usually surrounding one or more lipid droplets often with internalized membrane fragments (3). The present study documents liver alteration after a short term single dose exposure to PCBs with high chlorine content, and correlates them with reported animal weights and central nervous system (CNS) measures. In the brain PCB congeners were concentrated in particular regions (4) while catecholamine concentrations were decreased (4-6). Urinary levels of homovanillic acid a dopamine metabolite were evaluated (7).Wistar rats were gavaged with corn oil (6 controls), or with a 1:1 mixture of Aroclor 1254 and 1260 in corn oil at 500 or 1000 mg total PCB/kg (6 at each level).

Acetaminophen: Macula densa hypersecretory activity by induced hepatotoxicity

1987 ◽  
Vol 45 ◽  
pp. 934-935
Author(s):  
S.S. Poolsawat ◽  
C.A. Huerta ◽  
S.TY. Lae ◽  
G.A. Miranda
Keyword(s):  
Cell Proliferation ◽  
Liver Function ◽  
Chronic Inflammation ◽  
Foam Cell ◽  
Term Effect ◽  
Short Term ◽  
Drug Induced ◽  
Experimental Induction ◽  
Tissue Alterations ◽  
Toxic Responses

Introduction. Experimental induction of altered histology by chemical toxins is of particular importance if its outcome resembles histopathological phenomena. Hepatotoxic drugs and chemicals are agents that can be converted by the liver into various metabolites which consequently evoke toxic responses. Very often, these drugs are intentionally administered to resolve an illness unrelated to liver function. Because of hepatic detoxification, the resulting metabolites are suggested to be integrated into the macromolecular processes of liver function and cause an array of cellular and tissue alterations, such as increased cytoplasmic lysis, centrilobular and localized necroses, chronic inflammation and “foam cell” proliferation of the hepatic sinusoids (1-4).Most experimentally drug-induced toxicity studies have concentrated primarily on the hepatic response, frequently overlooking other physiological phenomena which are directly related to liver function. Categorically, many studies have been short-term effect investigations which seldom have followed up the complications to other tissues and organs when the liver has failed to function normally.

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