View clinical trials related to Healthy Volunteers.
Filter by:The aim of this project is to investigate whether alterations in sensory-motor performances during weightlessness are only of theoretical relevance, or indeed restrict the capacity of the participants. To find out, volunteers will monitor a complex realistic process by operation of buttons and switches in weightlessness. The task will mimic the control of vehicles, research equipment and industrial processes. Effects of weightlessness will be separated from effects induced by stress and those of motivation through evaluation of cortisol and manipulation of motivation.
If investigators know that the anticipatory mechanisms involved in precision grip take into account the gravity, however it is unclear how they adapt to changes in the gravitational level. The objectives of this study are to study and model the movement control and the mechanisms underlying learning and adapting to the condition of weightlessness. Specifically, i) investigators will determine if a change in the level of gravity is taken into account when controlling grip force and ii) investigators will examine the effects of gravity change on hand-eye coordination.
In this project, investigators propose to study the jump in different reduced gravity fields obtained during parabolic flights profiles but also during increased gravity fields obtained during turns of the airplane or during the pull-up phase of the parabola. By means of a pneumatic device, an additional pull-down force will be added to the vertical force caused by the gravity field. By combining different levels of gravity to different levels of the added pull-down force it will be possible to dissociate the respective contribution of the otolithic and proprioceptive systems to the anticipatory landing response. To the investigators' knowledge, only one study has modified the gravity field during a jump. However, these authors did not add a pull-down force and only analyzed the vertical ground reaction force. A better knowledge of the sensory-motor control of the landing phase of a jump will also increase the investigators' understanding of the physiopathology of joint instability. Indeed, similarities could be found between the evolution of the motor response due to the absence gravity during long-duration space flights and the pathological process of chronic ankle and knee instability. The knowledge generated by this study will thus provide invaluable information in the context of human performance and rehabilitation.
CPAP will be applied to normal volunteers inorder to understand CPAP's effects on breathing and chest wall motion.
Background: There are no good treatments for people considering suicide. Researchers want to study suicide with questions, blood tests, brain imaging, and sleep studies. They hope to better understand suicide, so they can help suicidal people. Objective: To understand what happens in the brain when someone has thought about or attempted suicide. Eligibility: Group 1: Adults ages 18 70 who have thought about or attempted suicide recently Group 2: Adults ages 18 70 who have thought about or attempted suicide in the past Group 3: Adults ages 18 70 who have depression or anxiety, but have never thought about suicide Group 4: Healthy volunteers the same ages. Design: Participants will be screened in another protocol. Adults who have recently thought about or attempted suicide must be referred by a doctor. They may do up to 3 phases of this study. Groups 2, 3 and 4 will do only Phase 1 and will not get ketamine. Phase 1: 1 week in hospital. Participants will have: Physical exam. Questions about thoughts and feelings. Thinking and memory tests and simple tasks. Blood and urine tests. Two MRI scans. Participants will lie on a table that slides into a metal cylinder that takes pictures. They will have a coil over their head and earplugs and do a computer task. Sleep test. Disks and bands will be placed on the body to monitor it during sleep. Magnetic detectors on their head while they perform tasks. A wrist monitor for activity and sleep. Lumbar puncture (optional). A needle will collect fluid from the back. Shock experiments (optional). Participants will observe pictures and sounds and feel a small shock on the hand. Phase 2: 4 days in hospital. A thin plastic tube will be placed in each arm, one for blood draws, the other to get the drug ketamine once. Participants will repeat most of the Phase 1 tests. Phase 3: up to 4 more ketamine doses over 2 weeks. Participants will have follow-up calls or visits at 6 months and then maybe yearly for 5 years.
The primary objective of the study is to assess the safety and tolerability of a single dose of subcutaneous (SC) or intravenous (IV) administered fasinumab in healthy Japanese subjects.
There are no equivalent experiment setups to create comparable changes of gravitation such as during parabolic flights. To determine the initial orthostatic responses of the cardiovascular system under the gravitational conditions of mars and moon is an essential step for a better understanding of 1) the fundamental functions of the human cardiovascular system (basic research) 2) specific impact of partial-g on the human heart, lungs and vessels in a spaceflight-context 3) approaches for countermeasure development against orthostatic intolerance on moon and mars (applied research). Non-invasive measurement methods will be used to achieve the cardiovascular key values of the study: stroke volume (SV) and cardiac output determination by pulse contour analysis, impedance cardiography and inert gas rebreathing, beat-to-beat finger blood pressure measurement, heart rate and heart rate variability determination by ECG. All of these methods have proven their accuracy during parabolic flights. Nevertheless pulse contour analysis and impedance cardiography are known to provide only relative SV and CO values. Thus inert gas rebreathing gives us the possibility to calibrate these stroke volumes and cardiac outputs to absolute values. Success of this procedure was shown during former parabolic flights.
Previous studies have neglected two important aspects for the China National Space Administration. First, while biomechanical models are very sensitive to the characteristics of the subjects, data have been collected on subjects with biomechanical characteristics very different from those of "typical" Chinese astronauts. Second, pure video analysis techniques and kinematic data lack the necessary acceleration information important to understanding the forces exerted during movement and control of human motion. While some studies used force and moment sensors to aid in robot torque control and human joint work estimation, investigators are unaware of any studies performed in a microgravity environment that have combined the kinetic force and moment information with acceleration measurements to enable more reliable motion tracking without the need for acceleration estimation. This is why MICR0-G sensors and accompanying kinematic video system have been developed in order to provide for detailed analyses of the astronaut movement control strategy (joint forces and torques, kinetic and acceleration measurements). Knowledge of the joint torques permits us to calculate the joint and musculoskeletal dynamics required to execute the microgravity motions, as well to provide insight into the altered movement strategies in reduced gravity as compared to 1-G locomotion.
Parabolic flight is the only ground-based condition in which weightlessness (0G) can be created long enough for safely testing changes in human perception and behavior. In addition to the 0G period, parabolic flight generates equal duration periods of 1.8G, which present another unique opportunity to test the same responses to hypergravity and back to 1G. Cognitive function, together with good oculomotor control, eye-hand coordination, and spatial orientation perception, is a critical subsystem that is used by the CNS in the control of vehicles and other complex systems in a high-level integrative function. Evidence from space flight research demonstrates that the function of each of these subsystems is altered by the transitions in gravito-inertial force levels. These neuro-vestibular alterations, unfortunately, correspond to mission phases where physical and cognitive performance are particularly critical for crew safety and mission success. To date, there is only limited operational evidence that these alterations cause functional impacts on mission-critical vehicle (or complex system) control capabilities. However, the true operational risks will be estimable only after the investigators have filled the knowledge gaps and when the investigators can accurately assess integrated performance in off-nominal operational settings. Accurate perception of self-in-space motion and self-motion relative to other objects are critical to piloting, driving, and remote manipulator operations. Immediately after space flight, most crewmembers have reported some degree of disorientation/perceptual illusion, often accompanied by nausea (or other symptoms of motion sickness), and frequently manifested by lack of coordination, particularly during locomotion. Despite recent, intensive training, some Shuttle landings were outside of the desired performance boundaries. Scores indicating neurovestibular dysfunction in returning astronauts generally correlated with poorer flying performances, including a lower approach and landing shorter, faster, and harder. An underestimation of distance, coupled to an overestimation of tilt magnitude or misperception of the type of motion, could be at the origin of these poorer performances. This study should confirm that the unloading of the otoliths in weightlessness induces an alteration in the egocentric reference during space flight. Errors in egocentric localization might contribute at a higher level to the computation of misleading world-centered representations, and therefore be partly responsible for illusory sensations and motion sickness symptoms during space flight, and postural instability and oscillopsia after returning in a reduced or terrestrial gravitational force level. Beside their fundamental implications, the results of this study have also practical implications in the design of man-machine interfaces. Changes in judgment of distance in microgravity or in reduced gravity affect crew posture and reach, display orientation, and other visual cues, which should be considered in hardware and operations design.
The main goal of the study is demonstrate that e-Nose system function is not altered in weightlessness and more specifically that gas concentration measurements are the same in weightlessness and normal gravity.