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Neuroadaptation to Space Conditions-2

Effects of Spaceflight on Neural Working Memory and Visual Motor Adaptation

A pilot study on neural working memory changes during a space flight analog with high carbon dioxide levels revealed that increased/decreased activation in frontal temporal and parietal regions was associated with improvements in spatial working memory.

This provided evidence for the influence of neural changes in specific brain regions on working memory performance.

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Image-1-The Impact of Space Flight on Neural Working Memory and Visual Motor Adaptation. (Created by AI)

Neural Working Memory

  • Performance Decline : Astronauts were found to experience a decline in working memory performance during and after spaceflight. This decline is attributed to stress in the microgravity environment and altered sensory input.
  • Neural Activity : Using functional MRI (fMRI) researchers observed changes in neural activity in the prefrontal cortex a region critical for working memory. Decreased activation in this area indicates possible difficulties in maintaining working memory function.

Visual Motor Adaptation

Another study investigated changes in neural working memory during a spaceflight analog focusing on visual-motor adaptation.

The findings showed that astronauts used mental rotation strategies to adapt to the International Space Station (ISS) environment and demonstrated the brain’s ability to adjust visual-motor control in response to the challenges of spaceflight.

  • Motor Skill Changes : Studies have reported significant changes in visual motor adaptation the ability to coordinate visual inputs with motor actions. Astronauts showed a progressively declining performance on tasks requiring precise hand-eye coordination.
  • Neural Adaptation : The studies highlighted adaptations in brain regions associated with visual-motor control such as the parietal and occipital lobes. These regions exhibited altered connectivity patterns reflecting the brain’s efforts to adapt to the microgravity environment.

Effects of Spaceflight Stressors on Brain Volume, Microstructure, and Fluid Distribution

Studies investigating the effects of spaceflight stressors on brain volume microstructure and intracranial fluid distribution have shown that disruptions in brain areas involved in prefrontal multimodal integration of sensory inputs affect functions such as visual-motor control and higher-order visuospatial processing.

These findings underscore the structural changes in the brain caused by spaceflight stressors and emphasize the need to understand the mechanisms underlying these changes.

Brain Volume

  • Volume Reduction : A reduction in gray matter volume was found in certain areas such as the frontal and temporal lobes. This volume loss was more pronounced in astronauts with longer missions.
  • Ventricle Enlargement : There was an increase in the size of the brain ventricles; this is indicative of changes in CSF dynamics and brain structure.

Microstructure

  • White Matter Integrity: The integrity of white matter tracts was compromised especially in areas related to motor and sensory processing. Diffusion tensor imaging (DTI) revealed decreased fractional anisotropy suggesting microstructural damage or remodeling.
  • Neuroplastic Changes : As the brain adapted to the prolonged absence of gravity signs of neuroplastic changes began to appear. These changes were reflected in the altered connectivity and microstructural properties of white matter.

Liquid Dispensing

  • BOS Redistribution : Significant changes in CSF distribution were reported. Microgravity caused fluid to shift forward leading to increased intracranial pressure and changes in CSF volume around the brain.
  • Intracranial Pressure: Increased intracranial pressure due to fluid redistribution was thought to be related to the observed structural brain changes such as ventricular enlargement and brain tissue displacement.

Neurochemical Signaling and Cognitive Function

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Image-2. Neurochemical Signaling and Cognitive Function. (Created by AI)

Modulation of Neurotransmitter Systems and Cognitive Changes During Space Missions Space missions bring stressors and environmental conditions that can significantly affect neurotransmitter systems in the brain and lead to cognitive changes. These changes are crucial for understanding how the brain adapts and functions in space.

Neurotransmitter Modulation

  • Dopamine : Dopaminergic pathways are particularly sensitive to stress and novel environments. Spaceflight can alter dopamine levels affecting functions such as reward processing motivation and executive function. Altered dopamine signaling can lead to problems with focus decision-making and mood regulation.
  • Serotonin : Serotonin levels are also affected by the stress and isolation experienced during space missions. Changes in serotonin signaling can affect mental health anxiety levels and sleep patterns which are critical in maintaining mental health and cognitive function.
  • GABA and Glutamate: These neurotransmitters are crucial in maintaining the excitatory/inhibitory balance in the brain. Alterations in GABAergic and glutamatergic signaling can affect cognitive functions such as learning memory and spatial orientation.

Cognitive Changes

  • Memory and Learning : Changes in neurotransmitter levels can impair working memory and learning abilities. In astronauts reduced activation in memory-related regions such as the hippocampus can hinder their ability to retain and process new information.
  • Attention and Executive Function : Modulated neurotransmitter systems can lead to difficulties in maintaining attention and performing executive tasks. These cognitive functions are essential for problem solving and managing complex task operations.

Effects of Increased Brain Activation for Dual Mission and Relevance to Spaceflight

A study investigating increased brain activation for the dual task during 70 days of head-down bed rest (HDBR) suggested that greater neurocognitive control is required for dual task execution during HDBR compared to pre- and post-HDR conditions.

This result indicated that brain activation patterns are influenced by dual-task demands which may have implications for performance in spaceflight scenarios.

Increased Brain Activation

  • Cognitive Load : Dual tasking increases cognitive load leading to greater activation in brain regions involved in attention working memory and motor control. The prefrontal cortex in particular shows high activity as it coordinates the simultaneous processing of multiple tasks.
  • Resource Allocation : The brain must efficiently allocate resources to manage dual tasks. This can challenge cognitive systems especially in the harsh space environment where sensory inputs and motor demands are different from those on Earth.

Relevance to Space Flight

  • Operational Demands : Astronauts are often required to perform multiple tasks at the same time such as conducting ground observation studies while performing spacewalks. The increased brain activation for dual-tasking highlights the cognitive demands placed on astronauts during these operations.
  • Cognitive Fatigue : Constant dual-tasking can cause cognitive fatigue reduce productivity and increase the likelihood of errors. In space where precision and attention to detail are critical understanding the impact of dual-tasking on cognitive functions is vital.
  • Training and Countermeasures : Insights from studies of brain activation during a dual mission can inform training programs designed to increase astronauts’ cognitive resilience. Techniques such as cognitive training stress management and neurological feedback can help mitigate the negative effects of the dual mission and improve overall mission performance.

In our last part we will talk about the neuroplasticity and brain health, and future research directions and mitigation strategies. Until next time, take care of your ‘nerves’!

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Note: The sources of this article will be listed at the end of section 3.

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Doktor, MoEP Uzay Nörobilim Takımı (NEUR-PACE) üyesi ve yazarı. (Doctor - MoEP Space Neuroscience Team - NEUR-PACE crew and author)

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