The "Space" Component of Professor Meygal's Research
PetrSU Professor Alexander Meygal is known not only for his research in human and animal physiology but also as a scientist who participated in the international Mars500 project. Today, world-class scientist Alexander Yuryevich Meygal, Head of the Department of Human and Animal Physiology and Pathophysiology, and Director of the Laboratory of New Physiological Research Methods at the Scientific and Educational Center for High Biomedical Technologies at the Zilber Medical Institute, discussed his current research.
Alexander Yuryevich, is there still a "space" component in your research?
“Yes, issues of gravity and weightlessness remain at the center of our scientific research. Currently, we focus primarily on fundamental physiological issues—the phenomenon of muscle tone and the mechanisms of antigravity activity, as we discuss the physiology of movement, and issues of heart rhythm regulation in health and disease.
Muscle tone is diverse, heterogeneous, and manifests itself in many ways. For example, muscle rigidity is characteristic of Parkinson's disease, catalepsy of schizophrenia, and spasticity of muscles after a stroke. There is also normal postural tone. Tonic immobilization and thermoregulatory tone are also observed as behavioral responses. All these phenomena have much in common from a neurophysiological perspective.
Since muscle tone is no longer needed to counteract gravity in zero-gravity conditions, it simply disappears. This is precisely why we conducted a long-term study on the possibility of reducing muscle rigidity in individuals with Parkinson's disease. From a theoretical perspective, we demonstrated that rigidity is gravity-dependent, as it does indeed decrease during dry immersion, which we use as a ground-based model of weightlessness.
We also demonstrated that, in zero-gravity conditions, heart rate variability (Professor L.I. Gerasimova-Meygal) and the ability to solve complex cognitive problems are altered in Parkinson’s patients. We also demonstrated that Parkinson’s disease is partially gravity-dependent.
What are you currently working on?
“We have recently completed a Russian Science Foundation project to study postactivation tonic automatism (the Kohnstamm phenomenon) in ground-based weightlessness and are preparing for the next stage – studying this phenomenon in conditions of increased gravity, with altered verticality and support, and in Parkinsonism.
Recently, another model (of which there are already about ten) of the effects of weightlessness on the human body has emerged: the vestibular hypofunction model. In close collaboration with Associate Professor E.N. Kravtsova, we have conducted extensive research into the mechanisms of vestibular hypofunction. We have shown that exposure to bone conduction sound, introduced into our laboratory by Associate Professor E.N. Kravtsova, increases the Kohnstamm phenomenon, or involuntary muscle tone, which clearly indicates the involvement of the brain's reticular formation in muscle tone. This is purely fundamental science.
We use a method of sequentially switching off sensory systems, which also simulates weightlessness, and have developed a calculator for assessing their contribution to the body's spatial orientation. Professor L.I. Gerasimova-Meygal successfully uses the dry immersion method to study human hemodynamics and heart rhythm in combination with laser Doppler flowmetry. In total, we published 10 articles in the journals "Aerospace and Environmental Medicine," "Human Physiology," and "Russian Otolaryngology" in 2025–2026.
Two years ago, we participated in processing data from the International Space Station, publishing an article on muscle electromyography and the potential of digital biopsy. We hope to continue to be useful in the future.
All of our research projects are always interconnected and build upon one another. Parkinsonism, although an unpleasant disease, still offers a unique opportunity to study posture, movement, and tremors. Electromyography, which we've been working with since 1970, remains our favorite method, which we're currently evaluating at a new level—in terms of dimensionality, recurrence, and entropy. It was thanks to electromyography that we began researching Parkinsonism, which led us to the Mars500 project, after which we created a project to study Parkinsonism in zero gravity, which led to us being invited to evaluate the electromyograms of cosmonauts.
How did it all begin?
“It all began with the problem of thermoregulatory muscle tone and cold shivering, and the world of motor units, which Professor Yu.V. Lupandin introduced us to. In turn, the topic of thermoregulation in the Department of Human and Animal Physiology was founded by Professor O.P. Minut-Sorokhtina. While combing through the department's archives and old publications, I discovered an interesting article by Professor G.N. Sorokhtin, in which, as the founder of the theory of "excitation deficit and atonia of the nervous center," he wrote about its applicability to understanding the effects of weightlessness on muscle tone back in 1974. This is now known as the theory of "functional deafferentation," which we also use. It could be said that the seeds of space exploration were already planted mentally by our predecessors, and it's not surprising that we have taken up this idea. In a certain sense, we continue to develop the theory of "excitation deficit."
Space can be seen in virtually every function of the human body, yet most space exploration is still conducted on Earth – by astronomers and through weightlessness simulations.
