AGBRESA: HyperCampus – How does artificial gravity affect plasticity of the brain?
"Do not disturb – Experiment ongoing!" is the message hanging from the door of participants' rooms during the AGBRESA studies. Often, a concession of scientists and medical staff march in and out of the participants' rooms – which are usually open – to administer various experiments – to transport them via gurney to the experiments in the nearby modules of the aerospace medicine research facility: envihab.##markend##
One such experiment is the HyperCampus experiment, which seeks to measure the effect of bedrest and artificial gravity on the structural and functional capacities of the brain. The HyperCampus experiment takes place with the participants lying in bed in their rooms as well as in the adjacent magnetic resonance imaging room (MRI). The experiment is being performed by Alexander Stahn, Assistant Professor of Medical Science in Psychiatry at the Perelman School of Medicine of the University of Pennsylvania, on behalf of NASA. Every day, two DLR employees – Dorothee Fischer and Sarah Weidenfeld – visit the participants with a laptop connected to an easily accessible pivot arm allowing participants to complete some of the HyperCampus experiments in the relaxed environments of their beds, which are inclined toward the head by six degrees.
Acting as terrestrial astronauts, the participants take daily rides on the centrifuge, which generates artificial gravity. The participants must cooperate to enable identification of the changes in the brain – specifically the hippocampus, which is responsible for orientation – so they perform a variety of cognition tests before, during and after the bedrest in their rooms and under the MRI scanner. Their results inform the equation that determines how changes in the brain affect performance.
Cognitive ability and artificial gravity
Ultimately, Stahn hopes that analysis of the data will yield important insights into how people orient themselves – and therefore navigate – in three-dimensional space. With this series of experiments within the AGBRESA study, NASA is looking to minimise the health risk of astronauts, especially on long-term missions. One important area of interest is the neurocognitive impairment caused by a weightless environment in space. Artificial gravity might play an important role in this regard. This is precisely what the AGBRESA study at :envihab in Cologne is investigating: as a training method, two-thirds of the participants are exposed to artificial gravity during regular rides on the centrifuge, while one third of the participants act as a control group and do not complete any rides on the short-arm centrifuge.
"Barely any studies have looked into the neurophysiological correlation between changes in cognitive performance and artificial gravity so far," says Stahn: "While the physical deconditioning of the cardiovascular system and muscle and bone atrophy have been quite thoroughly researched, comparatively speaking, we actually know very little about what happens in the brain. Indeed, there have been no analyses so far on the effects of intermittent, artificial gravity on structural changes in the brain." He wants to change this situation with his cognitive test setup within the AGBRESA study: "Latest investigations also indicate that bedrest causes profound alterations in spatial orientation, as well as in the brain's structure and functions. Our overarching goal is to analyse the repercussions of 60 days of bedrest with a downward inclination toward the head – both with and without artificial gravity – as a countermeasure to structural and functional neuroplasticity and the significance of its associated behaviours." This mainly involves observations of spatial thinking and neuronal pathways, which are achieved by combining a series of highly advanced brain imaging sequences for the assessment of cognitive performance with virtual reality technology.
Cognition tests in a bed inclined downward by six degrees
To measure cognition, the participants complete two batteries of tests, each comprising several test sections: some are structured similarly to standard intelligence tests and record logical thinking and memory whilst others identify processing speed and responses. What risks are the participants willing to take and what is their memory like today?
In some cases, the participants navigate through earthly landscapes and labyrinths during the tests whilst in others they navigate a starry canopy without fixed points of reference. Instead of the computer applications, the participants in the AGBRESA study occasionally wear a virtual reality headset that they use to solve tasks while moving naturally in a simulated, three-dimensional space that is as realistic as possible. The tests will be repeated regularly over the three months of the AGBRESA study to map development over time. One session lasts between 20 and 30 minutes. "We know from experience that speed is preferred to accuracy after prolonged periods of physical inactivity. We need to understand which processes determine these decisions, in order to minimise the risks for space missions," concludes Stahn.