Short-term microgravity effects simulation does not affect fNIRS measures of cerebral oxygenation changes induced by cognitive load.

In the past decade, there has been a surge in interest in space exploration studies, particularly due to the prospect of exploring distant planets such as Mars. However, long-duration space missions may pose cognitive challenges resulting from spaceflight-induced perceptual and motor changes, prolonged cephalic fluid shifts, and high cognitive load. One method for monitoring cognitive activity is functional near-infrared spectroscopy (fNIRS), a technique not yet tested under prolonged microgravity conditions beyond parabolic flight periods.

Eye-brain axis in microgravity and its implications for Spaceflight Associated Neuro-ocular Syndrome.

Long-duration human spaceflight can lead to changes in both the eye and the brain, which have been referred to as Spaceflight Associated Neuro-ocular Syndrome (SANS). These changes may manifest as a constellation of symptoms, which can include optic disc edema, optic nerve sheath distension, choroidal folds, globe flattening, hyperopic shift, and cotton wool spots. Although the underpinning mechanisms for SANS are not yet known, contributors may include intracranial interstitial fluid accumulation following microgravity induced headward fluid shift.

How does head position induced intracranial pressure changes impact sympathetic activity and cerebral blood flow?

Purpose: Acute head-down-tilt (HDT) simulates short duration hemodynamic impact of microgravity. We sought to determine whether an increase in ICP caused by acute HDT affects sympathetic nervous system activity and cerebral blood flow velocities (CBFV) in healthy male volunteers.

Methods: HDT protocol was established as follows: basal condition immediately followed by gradual negative angles (-10°, -20° and -30°) lasting 10mn and then a return to basal condition.

Clinical effects of thigh cuffs during a 7-day 6 degrees head-down bed rest.

Thigh cuffs are used by Russian cosmonauts to limit the fluid shift induced by space flight. A ground simulation using the head-down bed rest (HDBR) model was performed to assess the effects of thigh cuffs on clinical tolerance and orthostatic adaptation. 8 male healthy volunteers (32.