Microgravity’s effect on the neurological aspect of living organisms; relative to space

By Subhana Iqbal

Abstract:

In this research article, the effects of microgravity on the human brain will be discussed. The primary objective of this paper is to analyze the changes in molecular and anatomical health of the neurons and the brain after extensive periods of time in the presence of weakened gravity. Microgravity is used to describe a weakened state of gravity. For instance, airplanes can be utilized to create microgravity when they rise and fall in the shape of a parabola. It is well known that space has a significantly lower acceleration due to gravity than earth. For that reason, qualified health practitioners that have studied aerospace medicine assess the health and safety of humans that have or will experience microgravity in space. Secondary aims canvass the disorders that have arisen due to cause.

Neural anatomy and physiology

From a microscopic viewpoint, it was confirmed that when experiencing microgravity, the plasma of neuronal cells becomes less viscous. Electrophysiological properties of neurons have also been altered in minimized gravity1. Multi-electrode array (MEA) technology is a non-invasive mechanism that allows scientists to measure the electrical activity of neurons in action. At the resting potential, neuronal cells are slightly depolarized 2. The increased excitability of the neurons causes voltage-gated sodium ion channels to open more frequently compared to voltage-gated potassium ion channels (Kohn 2012). In contrast, the rate of action potentials increases under the influence of microgravity (Meissner and Hanke 2005). Therefore, it is proposed that microgravity does in fact influence neuronal activity.

Brain anatomy

Neuroimaging studies have found out that ventricular systems containing cerebrospinal fluid (CSF) are affected by microgravity. The ventricular system controls the production and transport of CSF in the brain. CSF acts as a protective cushion that removes waste products and allows cells to absorb nutrients. The ISS has discovered certain alterations of the macroscopic brain of astronauts, including narrowing of the cerebral sulcus and increased ventricular volume of approximately 10.7%3 (Robert et al., 2017). An increase in ventricular volume is associated with neurodegenerative diseases. The mammalian brain is made of grey matter (GM) and white matter (WM). Microgravity may not affect brain matter. However, an increase in the summated mean brain and CSF volumes post-flight was reported by ISS crew members, linking back to the increased rates of action potentials. Increased volumes of CSF can lead to brain damage or even brain death.

Microgravity in space and neurodegenerative diseases

Neurodegenerative disease is the continuation of the loss or death of neurons over a long period of time. Examples may include Alzheimer's disease and Parkinson's disease. The exposure of certain protein clumps in the brain is the main cause of these diseases, although there is no certain causation of the presence of the proteins. Researchers in NASA space stations have discovered the formation of protein aggregations called Amyloid fibrils in the brains of astronauts, which is associated with Alzheimer's disease. Another relevant experiment illustrates that neurons may be predisposed under microgravity; this was tested using mice and measuring protein levels in the hippocampus, which is involved in memory, learning, and emotions 4(Sarkar et al.). All the functions listed above are also impaired in patients with Alzheimer's disease. One of the many proteins that have decreased in the tested mice was pyruvate hydrogenase, which is essential for oxidative phosphorylation. A decrease in ATP production is detrimental for the Na+/K+ ion pump in the axon membrane. Therefore, irregularities in the potential difference between the inner and outer axons are expected. It is believed that the dysfunction of pyruvate metabolism may be causing neurodegeneration.

Conclusion:

In summary, microgravity does in fact affect neurons and the brain, as supported by many researchers and experiments. Ongoing assessments are being performed to understand the complexity of the human brain and treat neurodegenerative diseases effectively. New technologies, such as MEA, are being produced in order to understand the effects of microgravity on neurons on a molecular level. The continuous research scientists accumulate surrounding the topic of microgravity will ensure a plausible treatment for Alzheimer's disease and other illnesses.

Written by: Subhana Iqbal