Space Medicine: A Story of Great Levity
Boarding now for a lab unlike any other! This research project conducted by Olivier White from the Cognition, Action and Sensorimotor Plasticity (CAPS) Unit in Dijon involves disrupting the Earth’s gravity aboard Airbus A310 Zero-G.
"A radical way of understanding how the human brain controls movement is to disrupt its functioning!" explains Olivier White, motor control specialist in the Cognition, Action and Sensorimotor Plasticity (CAPS) Unit* led by Charalambos Papaxanthis in Dijon. Under the influence of the Earth’s gravity, the brain, like an orchestra conductor, harmonizes sensory information from multiple sources in order to calibrate our movements. Among them:
- proprioception, through which receptors in our muscles, ligaments and joints enable us to locate the various parts of our body with our eyes closed;
- the vestibular system in the inner ear, which plays a role in spatial orientation, the feeling of acceleration and the maintenance of balance;
- and finally, vision.
"What better than to modify the Earth’s gravity to which we are all subject since birth?" Such is the project being conducted by White in conjunction with various international teams and which consists of disrupting the entire body – except for the hand, which will be maintained under conditions of terrestrial gravity. In the space domain, this approach would enable us to find out whether it is necessary to develop systems for facilitating the movements of pilots or whether it is better to let the brain handle the disruption alone. The findings obtained could ultimately also lead to progress in medicine, particularly when it comes to the motor rehabilitation of stroke or hemiplegia patients. Now the time has come for us to leave the lab bench. We have a plane to catch!
This parabolic flight campaign was funded by CNES.
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Now boarding Airbus A310 Zero-G. This aircraft unlike any other hosts scientific parabolic flight experiments. As its name suggests, the plane follows the trajectory of a parabola in which upwards and downwards maneuvers are alternated. This means that its passengers are subjected to variations in gravity. ©Inserm/CAPS Unit/CNES -
Marie Barbiero, postdoc in the Cognition, Action and Sensorimotor Plasticity Unit (CAPS), was able to experience the feeling of weightlessness. During the ascending and descending phases of the parabola, hypergravity occurs – which is when a passenger weighs almost twice their weight. And before reaching the summit of the parabola, the pilot substantially reduces the aircraft’s engine thrust, whereupon it enters the zero-gravity phase. The subject no longer feels their weight and floats freely for around 22 seconds. ©Inserm/CAPS Unit/CNES -
This parabolic flight campaign, funded by the French Space Agency (CNES), is the fruit of months of work in addition to technical and regulatory developments. Various types of equipment can be found on board. For example, cameras used to video the movements of the individuals, and a seat – taken from a racing car – in which the subjects will sit. ©Inserm/CAPS Unit/CNES -
During the initial tests, the volunteers are required to perform a precision pointing exercise, under full influence of the changes in gravity. This experiment is used to collect reference measurements in order to see how the subjects adapt to the situation. They then continue their task, this time with their hand under the influence of the Earth’s gravity. ©Inserm/CAPS Unit/CNES -
Pinpoint – as precisely as possible – targets on a touchscreen. This is the mission assigned to the subjects for this flight. Positioned in the car seat facing the screen, they are equipped with a stylus. During the variations in gravity, a motorized system connected to their wrist restores, in real time, terrestrial gravity to their hand. ©Inserm/CAPS Unit/CNES -
Many additional parameters are measured in parallel to the precision of the pointing. Among them, the force of the fingers on the stylus. As the experiment progresses, this force decreases, revealing that the subject has been able to adapt. ©Inserm/CAPS Unit/CNES -
The electrical activity of the muscles and the trajectory of the arm are measured using electrodes and markers in the form of small white beads. These parameters evaluate the participants’ level of adaptation to gravitational variations. Data which can all be used in later studies. ©Inserm/CAPS Unit/CNES -
hunch. The brain can anticipate the effects of altered gravity which affects the whole body in a consistent manner. Therefore, an assisted-movement device aiming to restore the Earth’s gravity to just the pilot’s hands appears unsuitable. And for good reason: it would only represent an additional disruption to handle in addition to the altered gravity. ©Inserm/CAPS Unit/CNES
And as a bonus, a short video! (🚨Spoiler alert🚨: the much-awaited 22 seconds of weightlessness begin at around 00:00:50.)
Note:
*Inserm/Université de Bourgogne, University Hospital of Dijon Unit 1093.
