Riascos of the University of Texas Health Science Center Scott J. Seidler of the University of Florida Daniel L. Richmond of the University of Florida Heather R. In addition to Piantino and Silbert, co-authors included first authors Kathleen E. “These findings not only help to understand fundamental changes that happen during space flight, but also for people on Earth who suffer from diseases that affect circulation of cerebrospinal fluid,” Piantino said. Piantino said the study could be valuable in helping to diagnose and treat Earth-bound disorders involving cerebrospinal fluid, such as hydrocephalus. Silbert, M.D., M.C.R., professor of neurology in the OHSU School of Medicine, to measure changes in these perivascular spaces through MRI scans. Researchers used a technique developed in the laboratory of co-author Lisa C. Enlargement of these spaces occurs in aging, and also has been associated with the development of dementia. The perivascular spaces measured in the brain amount to the underlying “hardware” of the glymphatic system. Scientists say this system seems to perform optimally during deep sleep. Known as the glymphatic system, this brain-wide network clears metabolic proteins that would otherwise build up in the brain. These spaces are integral to a natural system of brain cleansing that occurs during sleep. Researchers decided to find out by measuring perivascular spaces, where cerebrospinal fluid flows in the brain. Once you remove gravity from the equation, what does that do to human physiology?” “Nature didn’t put our brains in our feet - it put them high up. “We all adapted to use gravity in our favor,” Piantino said. Unbound by the forces of gravity, the normal flow of cerebrospinal fluid in the brain is altered in space.
Human physiology is based on the fact that life evolved over millions of years while tethered to Earth’s gravitational pull. In comparing a large group of deidentified astronauts, the study is among the first to comparatively assess an important aspect of brain health in space. In all cases, scientists found no problems with balance or visual memories that might suggest neurological deficits among astronauts, despite the differences measured in the perivascular spaces of their brains. “Experienced astronauts may have reached some kind of homeostasis,” Piantino said. Astronauts’ images were compared with those taken of the same perivascular space in the brains of 16 Earth-bound control subjects.Ĭomparing before and after images, they found an increase in the perivascular spaces within the brains of first-time astronauts, but no difference among astronauts who previously served aboard the space station orbiting earth. They also took MRI measurements again at one, three and six months after they had returned. Researchers used magnetic resonance imaging to measure perivascular space - or the space around blood vessels - in the brains of astronauts prior to their launch and again immediately after their return. The research involved imaging the brains of 15 astronauts before and after extended tours of duty on the International Space Station. “It also forces you to think about some basic fundamental questions of science and how life evolved here on Earth.”
The current data indicate that basilar membrane vibration was not involved in the backward propagation of otoacoustic emissions and that sounds exit the cochlea probably through alternative media, such as cochlear fluids.“These findings have important implications as we continue space exploration,” said senior author Juan Piantino, M.D., assistant professor of pediatrics (neurology) in the OHSU School of Medicine. Under postmortem conditions, the electrically evoked emissions showed no significant change while the basilar membrane vibration nearly disappeared. For a given frequency, the phase measured at a basal location led that at a more apical location, indicating that either an electrical or an acoustical stimulus evoked a forward travelling wave. For a given longitudinal location, electrically evoked basilar membrane vibrations showed the same tuning and phase lag as those induced by sounds. To understand how the inner ear-generated sound, i.e., otoacoustic emission, exits the cochlea, we created a sound source electrically in the second turn and measured basilar membrane vibrations at two longitudinal locations in the first turn in living gerbil cochleae using a laser interferometer.
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