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1.
Sci Rep ; 12(1): 922, 2022 01 18.
Artigo em Inglês | MEDLINE | ID: mdl-35042915

RESUMO

The space immediately surrounding the body is crucial for the organization of voluntary motor actions and seems to be functionally represented in the brain according to motor capacities. However, despite extensive research, little is known about how the representation of peripersonal space is adjusted to new action capacities. Abrupt exposure to a new force field has been shown to cause the representation of peripersonal space to shrink, possibly reflecting a conservative spatial strategy triggered by consciously-perceived motor errors. The present study assessed whether the representation of peripersonal space is influenced by gradual exposure of reaching movements to a new force field, produced by a stepwise acceleration of a rotating platform. We hypothesized that such gradual exposure would induce progressive sensorimotor adaptation to motor errors, albeit too small to be consciously perceived. In contrast, we hypothesized that reachability judgments, used as a proxy of peripersonal space representation, would not be significantly affected. Results showed that gradual exposure to Coriolis force produced a systematic after-effect on reaching movements but no significant change in reachability judgments. We speculate that the conscious experience of large motor errors may influence the updating of the representation of peripersonal space.


Assuntos
Atividade Motora/fisiologia , Espaço Pessoal , Córtex Sensório-Motor/fisiologia , Aclimatação , Adaptação Fisiológica , Força Coriolis , Retroalimentação Sensorial/fisiologia , Feminino , Humanos , Julgamento , Masculino , Movimento , Percepção Espacial/fisiologia , Adulto Jovem
2.
Artigo em Inglês | MEDLINE | ID: mdl-34886576

RESUMO

This study investigated the effects of yelling intervention on symptoms and autonomic responses in motion sickness. Forty-two healthy participants were recruited, and they participated in Coriolis stimulation, a technique for inducing motion sickness. The experimental procedure comprised five 1-min rotating stimuli with 1-min rest after each stimulus. Then, the symptom severity was assessed using the Motion Sickness Symptom Rating (MSSR). The d2 Test of Attention scores and cardiovascular responses were recorded before and after Coriolis stimulation. The electrocardiogram results were documented to analyze heart rate variability (HRV). During Coriolis stimulus, the participants were required to yell 5-8 times in the experimental trial, and to keep quiet for each minute of rotation in the control trial. The yelling intervention significantly reduced the MSSR score (p < 0.001). Nevertheless, it did not significantly affect the d2 Test of Attention scores. Yelling while rotating did not significantly affect the heart rate nor blood pressure. However, it decreased the normalized low frequency of HRV (p = 0.036). Moreover, it improved motion sickness, but its effect on attention was not evident. Motion sickness could significantly affect cardiovascular responses and HRV. However, yelling did not affect cardiovascular response, and it reduced sympathetic nervous system activity.


Assuntos
Enjoo devido ao Movimento , Sistema Nervoso Autônomo , Força Coriolis , Humanos , Percepção , Sistema Nervoso Simpático
3.
PLoS One ; 15(10): e0240666, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33075104

RESUMO

When we reach for an object during a passive whole body rotation, a tangential Coriolis force is generated on the arm. Yet, within a few trials, the brain adapts to this force so it does not disrupt the reach. Is this adaptation governed by a single-rate or dual-rate learning process? Here, guided by state-space modeling, we studied human reach adaptation in a fully-enclosed rotating room. After 90 pre-rotation reaches (baseline), participants were trained to make 240 to-and-fro reaches while the room rotated at 10 rpm (block A), then performed 6 reaches under opposite room rotation (block B), and subsequently made 100 post-rotation reaches (washout). A control group performed the same paradigm, but without the reaches during rotation block B. Single-rate and dual-rate models can be best dissociated if there would be full un-learning of compensation A during block B, but minimal learning of B. From the perspective of a dual-rate model, the un-learning observed in block B would mainly be caused by the faster state, such that the washout reaches would show retention effects of the slower state, called spontaneous recovery. Alternatively, following a single-rate model, the same state would govern the learning in block A and un-learning in block B, such that the washout reaches mimic the baseline reaches. Our results do not provide clear signs of spontaneous recovery in the washout reaches. Model fits further show that a single-rate process outperformed a dual-rate process. We suggest that a single-rate process underlies Coriolis force reach adaptation, perhaps because these forces relate to familiar body dynamics and are assigned to an internal cause.


Assuntos
Adaptação Fisiológica , Força Coriolis , Aprendizagem , Desempenho Psicomotor , Rotação , Adulto , Braço/fisiologia , Feminino , Voluntários Saudáveis , Humanos , Masculino , Adulto Jovem
4.
Analyst ; 144(12): 3782-3789, 2019 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-31094378

RESUMO

We investigate the influence of rotational forces on blood dynamics in a microfluidic device. The special confluence of Coriolis force and blood rheology is brought forth by analyzing the flow at different hematocrit (volume fraction of red blood cells) levels and rotational speeds. We further study the effects of channel layout and alignment with regard to the axis of rotation to understand this intricate interplay. We provide a sound basis for efficient designing of a lab on a compact disc (lab on CD) platform by harnessing the effects of Coriolis force at relatively much lower rotational speeds, in sharp contrast with the reported findings where Coriolis effects have been considered to be effective only for exceptionally high rotational speeds. Our results show that over certain intermediate regimes of rotational speeds, the flow profiles for different hematocrit levels are noticeably different. This, in turn, could be harnessed as a possible diagnostic signature of the hematocrit (or equivalently, packed cell volume) level, without necessitating the deployment of chemical consumables, in an energy efficient paradigm.


Assuntos
Sangue , Discos Compactos , Força Coriolis , Hematócrito/métodos , Dispositivos Lab-On-A-Chip , Viscosidade Sanguínea , Hematócrito/instrumentação , Humanos , Técnicas Analíticas Microfluídicas/instrumentação , Técnicas Analíticas Microfluídicas/métodos , Rotação
5.
J Neurophysiol ; 121(6): 2042-2060, 2019 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-30943111

RESUMO

In the companion paper (Bakshi A, DiZio P, Lackner JR. J Neurophysiol. In press, 2019), we reported how voluntary forward-backward sway in a rotating room generated medial-lateral Coriolis forces that initially deviated intended body sway paths. Pure fore-aft sway was gradually restored over per-rotation trials, and a negative aftereffect occurred during postrotation sway. Force plate recordings showed that subjects learned to compensate for the Coriolis forces by executing a bimodal torque, the distribution of which was asymmetric across the two legs and of opposite sign for forward vs. backward sway. To explain these results, we have developed an asymmetric, nonparallel-leg, inverted pendulum model to characterize upright balance control in two dimensions. Fore-aft and medial-lateral sway amplitudes can be biomechanically coupled or independent. Biomechanical coupling occurs when Coriolis forces orthogonal to the direction of movement perturb sway about the ankles. The model includes a mechanism for alternating engagement/disengagement of each leg and for asymmetric drive to the ankles to achieve adaptation to Coriolis force-induced two-dimensional sway. The model predicts the adaptive control underlying the adaptation of voluntary postural sway to Coriolis forces. A stability analysis of the model generates parameter values that match those measured experimentally, and the parameterized model simulations reproduce the experimentally observed sway trajectories. NEW & NOTEWORTHY This paper presents a novel nonparallel leg model of postural control that correctly predicts the perturbations of voluntary sway that occur in a rotating environment and the adaptive changes that occur to restore faithful movement trajectories. This engaged leg model (ELM) predicts the asymmetries in force distribution and their patterns between the two legs to restore accurate movement trajectories. ELM has clinical relevance for pathologies that generate postural asymmetries and for altered gravitoinertial force conditions.


Assuntos
Adaptação Fisiológica/fisiologia , Fenômenos Biomecânicos/fisiologia , Força Coriolis , Perna (Membro)/fisiologia , Modelos Biológicos , Equilíbrio Postural/fisiologia , Adulto , Humanos , Rotação
6.
J Neurophysiol ; 121(6): 2028-2041, 2019 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-30943090

RESUMO

Studying adaptation to Coriolis perturbations of arm movements has advanced our understanding of motor control and learning. We have now applied this paradigm to two-dimensional postural sway. We measured how subjects (n = 8) standing at the center of a fully enclosed rotating room who made voluntary anterior-posterior swaying movements adapted to the Coriolis perturbations generated by their sway. Subjects underwent four voluntary sway trials prerotation, 20 per-rotation at 10 rpm counterclockwise, and 10 postrotation. Each trial lasted 20 s, and subjects were permitted normal vision. Their voluntary sway during rotation generated Coriolis forces that initially induced rightward deviations of their forward sway paths and leftward deviations of their backward sway. Sagittal plane sway was gradually restored over per-rotation trials, and a mirror image aftereffect occurred in postrotation trials. Dual force plate data analysis showed that subjects learned to counter the Coriolis accelerations during rotation by executing a bimodal torque pattern that was asymmetric across legs and contingent on forward vs. backward movement. The experience-dependent acquisition and washout of this compensation indicate that an internal, feedforward model underlies the leg-asymmetric bimodal torque compensation, contingent on forward vs. backward movement. The learned torque asymmetry we observed for forward vs. backward sway is not consistent with parallel two-leg models of postural control. NEW & NOTEWORTHY This paper describes adaptation to Coriolis force perturbations of voluntary sway in a rotating environment. During counterclockwise rotation, sway paths are deviated clockwise, but full restoration of fore-aft sway is regained in minutes. Negative aftereffects are briefly present postrotation. Current parallel leg models of postural control cannot account for these findings, which show that postural control, like arm movement control, can adapt rapidly and completely to the Coriolis forces generated in artificial gravity environments.


Assuntos
Adaptação Fisiológica/fisiologia , Fenômenos Biomecânicos/fisiologia , Força Coriolis , Atividade Motora/fisiologia , Equilíbrio Postural/fisiologia , Adulto , Feminino , Humanos , Masculino , Rotação
7.
J Vis Exp ; (140)2018 10 05.
Artigo em Inglês | MEDLINE | ID: mdl-30346409

RESUMO

An experimental method for exploring the heat transfer characteristics of an axially rotating channel is proposed. The governing flow parameters that characterize the transport phenomena in a rotating channel are identified via the parametric analysis of the momentum and energy equations referring to a rotating frame of reference. Based on these dimensionless flow equations, an experimental strategy that links the design of the test module, the experimental program and the data analysis is formulated with the attempt to reveal the isolated Coriolis-force and buoyancy effects on heat transfer performances. The effects of Coriolis force and rotating buoyancy are illustrated using the selective results measured from rotating channels with various geometries. While the Coriolis-force and rotating-buoyancy impacts share several common features among the various rotating channels, the unique heat transfer signatures are found in association with the flow direction, the channel shape and the arrangement of heat transfer enhancement devices. Regardless of the flow configurations of the rotating channels, the presented experimental method enables the development of physically consistent heat transfer correlations that permit the evaluation of isolated and interdependent Coriolis-force and rotating-buoyancy effects on the heat transfer properties of rotating channels.


Assuntos
Força Coriolis , Temperatura Alta , Rotação , Modelos Teóricos
8.
J Vestib Res ; 27(2-3): 103-112, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29064824

RESUMO

PURPOSE: Explore the different vestibular physiologic response retention patterns after Coriolis acceleration training in student pilots and extend the results for use with Chinese astronauts in the future. METHODS: Twelve healthy control male subjects were screened from males familiar with vestibular training and who physically resembled the astronauts. Fourteen student pilots were selected from 23 participants by rotational vestibular function tests. All subjects were exposed to five-day continuous or intermittent Coriolis acceleration training. Subjective motion sickness (MS) symptom scores, electrocardiography, electrogastrography (EGG), post-rotatory nystagmus and renin-angiotensin system responses were measured before, during and after rotational vestibular function tests at different times after vestibular training. RESULTS: Subjects could tolerate 10 min or 15 min of vestibular with mild MS symptoms. Retention of vestibular autonomic responses (retention of MS symptom scores, heart rate variability, power density of EGG, variations in levels of arginine vasopressin) were approximately 1 week for control subjects and approximately 5 weeks for student pilots. Decreases in slow-phase velocity of post-rotatory nystagmus were maintained for 14 weeks for control subjects and 9 weeks for student pilots. CONCLUSIONS: Retention of the vestibulo-autonomic reaction after vestibular training was different for control subjects and student pilots. All parameters related to autonomic responses could be maintained at low levels after vestibular training for approximately 1 week for control subjects and approximately 5 weeks for student pilots. Uncoupling patterns between post-rotatory nystagmus and the vestibulo-autonomic reaction may be helpful in the design of clinical rehabilitation plans for balance-disorder patients and for exploration of artificial gravity in future space missions.


Assuntos
Sistema Nervoso Autônomo/fisiologia , Aviação/educação , Força Coriolis , Reflexo Vestíbulo-Ocular , Astronautas , Eletrocardiografia , Eletromiografia , Movimentos Oculares , Hormônios/sangue , Humanos , Masculino , Enjoo devido ao Movimento/fisiopatologia , Nistagmo Fisiológico/fisiologia , Pilotos , Sistema Renina-Angiotensina , Estômago/fisiopatologia , Estudantes , Testes de Função Vestibular , Adulto Jovem
9.
Aerosp Med Hum Perform ; 87(2): 108-13, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26802375

RESUMO

INTRODUCTION: Pilots' vision and flight performance may be impeded by spatial disorientation and high altitude hypoxia. The Coriolis illusion affects both orientation and vision. However, the combined effect of simultaneous Coriolis illusion and hypoxia on saccadic eye movement has not been evaluated. METHOD: A simulated flight was performed by 14 experienced pilots under 3 conditions: once under normal oxygen partial pressure and twice under reduced oxygen partial pressures, reflecting conditions at 5000 m and 6000 m (16,404 and 19,685 ft), respectively. Eye movements were evaluated with a saccadometer. RESULTS: At normal oxygen pressure, Coriolis illusion resulted in 55% and 31% increases in mean saccade amplitude and duration, respectively, but a 32% increase in mean saccade frequency was only noted for saccades smaller than the angular distance between cockpit instruments, suggesting an increase in the number of correction saccades. At lower oxygen pressures a pronounced increase in the standard deviation of all measures was noticed; however, the pattern of changes remained unchanged. DISCUSSION: Simple measures of saccadic movement are not affected by short-term hypoxia, most likely due to compensatory mechanisms.


Assuntos
Doença da Altitude/fisiopatologia , Força Coriolis , Movimentos Oculares/fisiologia , Simulação de Ambiente Espacial , Adulto , Humanos , Masculino , Movimentos Sacádicos/fisiologia , Adulto Jovem
10.
Bull Exp Biol Med ; 160(1): 61-3, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26608378

RESUMO

The effectiveness of antibody-based release-active preparations Impaza (antibodies to eNOS), Tenoten (antibodies to brain-specific protein S-100), Dietressa (antibodies to type 1 cannabinoid receptor), Brizantin (combined preparation, antibodies to brain-specific protein S-100 and type 1 cannabinoid receptor), and Divaza (combined preparation, antibodies to brain-specific protein S-100 and eNOS) in the prevention of vertigo was studied on the model of intermittent accumulation of Coriolis accelerations (ICCA). Modification of activity of vestibular receptors and signal systems by release-active preparations contributed to an increase in ICCA tolerance time. Combined preparation Impaza possessed the most significant antinaupathic properties. Brizantin was less potent in this respect.


Assuntos
Anticorpos/uso terapêutico , Enjoo devido ao Movimento em Voo Espacial/prevenção & controle , Aceleração/efeitos adversos , Adolescente , Adulto , Força Coriolis , Método Duplo-Cego , Combinação de Medicamentos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Náusea/etiologia , Náusea/fisiopatologia , Náusea/prevenção & controle , Óxido Nítrico Sintase Tipo III/imunologia , Disautonomias Primárias/etiologia , Disautonomias Primárias/fisiopatologia , Disautonomias Primárias/prevenção & controle , Receptor CB1 de Canabinoide/imunologia , Proteínas S100/imunologia , Índice de Gravidade de Doença , Enjoo devido ao Movimento em Voo Espacial/etiologia , Enjoo devido ao Movimento em Voo Espacial/fisiopatologia , Vestíbulo do Labirinto/efeitos dos fármacos , Adulto Jovem
11.
Artigo em Inglês | MEDLINE | ID: mdl-25871040

RESUMO

At high angles of attack, an aircraft wing stalls. This dreaded event is characterized by the development of a leading edge vortex on the upper surface of the wing, followed by its shedding which causes a drastic drop in the aerodynamic lift. At similar angles of attack, the leading edge vortex on an insect wing or an autorotating seed membrane remains robustly attached, ensuring high sustained lift. What are the mechanisms responsible for both leading edge vortex attachment and high lift generation on revolving wings? We review the three main hypotheses that attempt to explain this specificity and, using direct numerical simulations of the Navier-Stokes equations, we show that the latter originates in Coriolis effects.


Assuntos
Força Coriolis , Asas de Animais/fisiologia , Animais , Modelos Biológicos , Rotação
12.
Appl Biochem Biotechnol ; 175(8): 3778-87, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25737025

RESUMO

We report a fully automated DNA purification platform with a micropored membrane in the channel utilizing centrifugal microfluidics on a lab-on-a-disc (LOD). The microfluidic flow in the LOD, into which the reagents are injected for DNA purification, is controlled by a single motor and laser burst valve. The sample and reagents pass successively through the micropored membrane in the channel when each laser burst valve is opened. The Coriolis effect is used by rotating the LOD bi-directionally to increase the purity of the DNA, thereby preventing the mixing of the waste and elution solutions. The total process from the lysed sample injection into the LOD to obtaining the purified DNA was finished within 7 min with only one manual step. The experimental result for Salmonella shows that the proposed microfluidic platform is comparable to the existing devices in terms of the purity and yield of DNA.


Assuntos
Força Coriolis , DNA/isolamento & purificação , Técnicas Analíticas Microfluídicas/métodos , Salmonella/química , Centrifugação , DNA/química , Dispositivos Lab-On-A-Chip , Lasers , Salmonella/genética
13.
Exp Brain Res ; 232(4): 1095-108, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24477760

RESUMO

Subjects exposed to a rotating environment that perturbs their postural sway show adaptive changes in their voluntary spatially directed postural motion to restore accurate movement paths but do not exhibit any obvious learning during passive stance. We have found, however, that a variable known to characterize the degree of stochasticity in quiet stance can also reveal subtle learning phenomena in passive stance. We extended Chow and Collins (Phys Rev E 52(1):909-912, 1995) one-dimensional pinned-polymer model (PPM) to two dimensions (2-D) and then evaluated the model's ability to make analytical predictions for 2-D quiet stance. To test the model, we tracked center of mass and centers of foot pressures, and compared and contrasted stance sway for the anterior-posterior versus medio-lateral directions before, during, and after exposure to rotation at 10 rpm. Sway of the body during rotation generated Coriolis forces that acted perpendicular to the direction of sway. We found significant adaptive changes for three characteristic features of the mean square displacement (MSD) function: the exponent of the power law defined at short time scales, the proportionality constant of the power law, and the saturation plateau value defined at longer time scales. The exponent of the power law of MSD at a short time scale lies within the bounds predicted by the 2-D PPM. The change in MSD during exposure to rotation also had a power-law exponent in the range predicted by the theoretical model. We discuss the Coriolis force paradigm for studying postural and movement control and the applicability of the PPM model in 2-D for studying postural adaptation.


Assuntos
Força Coriolis , Movimento/fisiologia , Equilíbrio Postural/fisiologia , Rotação , Adulto , Idoso , Fenômenos Biomecânicos/fisiologia , Interpretação Estatística de Dados , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
14.
J Neurophysiol ; 111(5): 977-83, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24304863

RESUMO

In a rotating environment, goal-oriented voluntary movements are initially disrupted in trajectory and endpoint, due to movement-contingent Coriolis forces, but accuracy is regained with additional movements. We studied whether adaptation acquired in a voluntary, goal-oriented postural swaying task performed during constant-velocity counterclockwise rotation (10 RPM) carries over to recovery from falling induced using a hold and release (H&R) paradigm. In H&R, standing subjects actively resist a force applied to their chest, which when suddenly released results in a forward fall and activation of an automatic postural correction. We tested H&R postural recovery in subjects (n = 11) before and after they made voluntary fore-aft swaying movements during 20 trials of 25 s each, in a counterclockwise rotating room. Their voluntary sway about their ankles generated Coriolis forces that initially induced clockwise deviations of the intended body sway paths, but fore-aft sway was gradually restored over successive per-rotation trials, and a counterclockwise aftereffect occurred during postrotation attempts to sway fore-aft. In H&R trials, we examined the initial 10- to 150-ms periods of movement after release from the hold force, when voluntary corrections of movement path are not possible. Prerotation subjects fell directly forward, whereas postrotation their forward motion was deviated significantly counterclockwise. The postrotation deviations were in a direction consistent with an aftereffect reflecting persistence of a compensation acquired per-rotation for voluntary swaying movements. These findings show that control and adaptation mechanisms adjusting voluntary postural sway to the demands of a new force environment also influence the automatic recovery of posture.


Assuntos
Adaptação Fisiológica , Força Coriolis , Movimento , Equilíbrio Postural , Volição , Feminino , Humanos , Masculino
15.
Aviat Space Environ Med ; 84(11): 1196-200, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24279235

RESUMO

BACKGROUND: Airsickness (AS) still represents a major issue in aviation medicine and affects many student pilots and aircrew members. This study aimed at producing an update of the Italian Air Force rehabilitation program for AS, including data on a prolonged follow-up (> 8 yr). METHODS: Data from 20 military pilots with a past history of rehabilitation for incapacitating AS were compared to those of 65 normal controls. All individuals from both samples were categorized as dropouts or successfully employed in fast jets, multiengine air carriers, or helicopters. All AS individuals were analyzed before and after their treatment with the Coriolis Stress test (CST). RESULTS: The AS sample showed similar results with respect to the control group, with the same incidence of dropouts (15% vs. 14%) and destination to rotary wing flight lines (15% vs. 17%). All dropouts were observed within the first year after rehabilitation. A statistically non-significant trend of being employed in transport aircraft (50% of individuals vs. 34% in the control group) rather than in fast jets (20% vs. 35%) was observed in the AS sample. DISCUSSION: Within the AS sample, the rehabilitation protocol had a success rate of 85%. The effects of rehabilitation were long lasting (mean follow up: 8.3 +/- 2.5 yr). Moreover, the flight career of AS treated individuals did not significantly differ from controls. The pretreatment CST was helpful in calibrating the initial intensity and duration of the nauseogenic stimulation, while it was useless as a post-treatment analysis of the outcome from training.


Assuntos
Militares , Enjoo devido ao Movimento/reabilitação , Força Coriolis , Humanos , Masculino , Resultado do Tratamento
16.
Philos Trans A Math Phys Eng Sci ; 371(2004): 20120366, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24191118

RESUMO

Submarine channel-levee systems are among the largest sedimentary structures on the ocean floor. These channels have a sinuous pattern and are the main conduits for turbidity currents to transport sediment to the deep ocean. Recent observations have shown that their sinuosity decreases strongly with latitude, with high-latitude channels being much straighter than similar channels near the Equator. One possible explanation is that Coriolis forces laterally deflect turbidity currents so that at high Northern latitudes both the density interface and the downstream velocity maximum are deflected to the right-hand side of the channel (looking downstream). The shift in the velocity field can change the locations of erosion and deposition and introduce an asymmetry between left- and right-turning bends. The importance of Coriolis forces is defined by two Rossby numbers, RoW=U/Wf and RoR=U/Rf, where U is the mean downstream velocity, W is the width of the channel, R is the radius of curvature and f is the Coriolis parameter. In a bending channel, the density interface is flat when RoR∼-1, and Coriolis forces start to shift the velocity maximum when |RoW|<5. We review recent experimental and field observations and describe how Coriolis forces could lead to straighter channels at high latitudes.


Assuntos
Braço , Força Coriolis , Movimento
17.
J Neurophysiol ; 110(6): 1370-84, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23803330

RESUMO

We have previously shown that the Coriolis torques that result when an arm movement is performed during torso rotation do not affect movement trajectory. Our purpose in the present study was to examine whether torso motion-induced Coriolis and other interaction torques are counteracted during a turn and reach (T&R) movement when the effective mass of the hand is augmented, and whether the dominant arm has an advantage in coordinating intersegmental dynamics as predicted by the dynamic dominance hypothesis (Sainburg RL. Exp Brain Res 142: 241-258, 2002). Subjects made slow and fast T&R movements in the dark to just extinguished targets with either arm, while holding or not holding a 454-g object. Movement endpoints were equally accurate at both speeds, with either hand, and in both weight conditions, but subjects tended to angularly undershoot and produce more variable endpoints for targets requiring greater torso rotation. There were no changes in endpoint accuracy or trajectory deviation over repeated movements. The dominant right arm was more stable in its control of trajectory direction across targets, whereas the nondominant left arm had an improved ability to stop accurately on the target for higher levels of interaction torques. The trajectories to more eccentric targets were straighter when performed at higher speeds but slightly more deviated when subjects held the weight. Subjects did not slow their torso velocity or change the timing of the arm and torso velocities when holding the weight, although there was a slight decrease in their hand velocity relative to the torso. The delay between the onsets of torso and finger movements was almost twice as large for the right arm than the left, suggesting the right arm was better able to account for torso rotation in the arm movement. Holding the weight increased the peak Coriolis torque by 40% at the shoulder and 45% at the elbow and, for the most eccentric target, increased the peak net torque by 12% at the shoulder and 34% at the elbow. In accordance with Sainburg's dynamic dominance hypothesis, the right arm exhibited an advantage for coordinating intersegmental dynamics, showing a more stable finger velocity in relation to the torso across targets, decreasing error variability with movement speed, and more synchronized peaks of finger relative and torso angular velocities in conditions with greater joint torque requirements. The arm used had little effect on the movement path and the magnitude of the joint torques in any of the conditions. These results indicate that compensations for forthcoming Coriolis torque variations take into account the dynamic properties of the body and of external objects, as well as the planned velocities of the torso and arm.


Assuntos
Força Coriolis , Movimento/fisiologia , Torque , Adulto , Braço/fisiologia , Fenômenos Biomecânicos , Feminino , Lateralidade Funcional , Humanos , Masculino , Pessoa de Meia-Idade , Desempenho Psicomotor , Tronco/fisiologia
18.
Aviat Space Environ Med ; 84(5): 473-7, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23713212

RESUMO

BACKGROUND: Car sickness is a frequent and potentially disabling problem, commonly related to a theory of sensory conflict, in particular visuo-vestibular, and between actual and anticipated sensory signals. This study aimed to evaluate predictors of motion sickness (MS) in rally car co-drivers exposed to various accelerations. METHODS: The subjects were 85 rally co-drivers (21 women) who filled in a questionnaire investigating MS symptoms in 4 situations: 1) special stages (competition itself); 2) special stages reconnaissance; 3) reading a book in the car; and 4) rear-seat passenger. The main factors related to MS were also investigated. RESULTS: Women reported more MS than men only in the rear-seat passenger situation. MS is reported with increasing frequency in special stages (2.3%), special stages reconnaissance (15.3%), when reading a book in a car (25.9%), and as a rear-seat passenger (25.9%). Stress (63.0%), on-board smells (46.5%), and on-board temperature (43.0%) were the main risk factors for MS. DISCUSSION: In special stages, the lower MS occurrence could be related to the kind of visual input: central vision focuses mainly on accurate pace notes while peripheral vision is restricted by the crash helmet and the head being bent forward. A cognitive process involved in the interpretation of the dynamic environment may lead to anticipation of upcoming accelerations, optimizing integration of vestibular and proprioceptive signals. During reconnaissance, the constant change of gaze between looking at the specifics of the road and the road book for taking notes requires frequent adjustments of the gain of the vestibulo-ocular reflex and the associated head movements could generate Coriolis accelerations.


Assuntos
Condução de Veículo , Enjoo devido ao Movimento/etiologia , Adulto , Força Coriolis , Orelha Interna/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Enjoo devido ao Movimento/fisiopatologia , Odorantes , Propriocepção/fisiologia , Reflexo Vestíbulo-Ocular/fisiologia , Fatores de Risco , Estresse Psicológico/etiologia , Inquéritos e Questionários , Temperatura , Percepção Visual/fisiologia , Adulto Jovem
19.
Aviat Space Environ Med ; 84(2): 104-9, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23447847

RESUMO

BACKGROUND: Technological advances have allowed centrifuges to become more than physiological testing and training devices; sustained G, fully interactive flight simulation is now possible. However, head movements under G can result in vestibular stimulation that can lead to motion sickness (MS) symptoms that are potentially distracting, nauseogenic, and unpleasant. In the current study an MS adaptation protocol was tested for head movements under +Gz. METHODS: Experienced pilots made 14 predetermined head movements in a sustained G flight simulator (at 3 +Gz) on 5 consecutive days and 17 d after training. Symptoms were measured after each head turn using a subjective 0-10 MS scale. The Simulator Sickness Questionnaire (SSQ) was also administered before and after each daily training session. RESULTS: After five daily training sessions, normalized mean MS scores were 58% lower than on Day 1. Mean total, nausea, and disorientation SSQ scores were 55%, 52%, and 78% lower, respectively. During retesting 17 d after training, nearly all scores indicated 90-100% retention of training benefits. DISCUSSION: The reduction of unpleasant effects associated with sustained G flight simulation using an adaptation training protocol may enhance the effectiveness of simulation. Practical use of sustained G simulators is also likely to be interspersed with other types of ground and in-flight training. Hence, it would be undesirable and unpleasant for trainees to lose adaptation benefits after a short gap in centrifuge use. However, current results suggest that training gaps in excess of 2 wk may be permissible with almost no loss of adaptation training benefits.


Assuntos
Força Coriolis , Gravitação , Movimentos da Cabeça/fisiologia , Enjoo devido ao Movimento/prevenção & controle , Adaptação Fisiológica , Humanos
20.
Laterality ; 18(3): 265-81, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-22708777

RESUMO

Why some humans prefer to rotate clockwise rather than anticlockwise is not well understood. This study aims to identify the predictors of the preferred rotation direction in humans. The variables hypothesised to influence rotation preference include handedness, footedness, sex, brain hemisphere lateralisation, and the Coriolis effect (which results from geospatial location on the Earth). An online questionnaire allowed us to analyse data from 1526 respondents in 97 countries. Factor analysis showed that the direction of rotation should be studied separately for local and global movements. Handedness, footedness, and the item hypothesised to measure brain hemisphere lateralisation are predictors of rotation direction for both global and local movements. Sex is a predictor of the direction of global rotation movements but not local ones, and both sexes tend to rotate clockwise. Geospatial location does not predict the preferred direction of rotation. Our study confirms previous findings concerning the influence of handedness, footedness, and sex on human rotation; our study also provides new insight into the underlying structure of human rotation movements and excludes the Coriolis effect as a predictor of rotation.


Assuntos
Força Coriolis , Lateralidade Funcional/fisiologia , Movimento/fisiologia , Rotação , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Distribuição de Qui-Quadrado , Criança , Cultura , Feminino , Pé/fisiologia , Humanos , Internacionalidade , Masculino , Pessoa de Meia-Idade , Sistemas On-Line , Valor Preditivo dos Testes , Fatores Sexuais , Inquéritos e Questionários , Adulto Jovem
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