Vocabulary that will help you understand this section

• atrophy
• autonomic nervous system
• biochemical
• central nervous system
• circadian
• physiological
• vestibular

Space neuroscience is a special area of space life sciences that seeks to understand the effects of space flight on the nervous system, and to use the microgravity environment of space to better understand how the nervous system functions under normal gravitational forces. In the past, space life sciences focused mainly on the health, safety and performance of the astronauts. Over the past decade, however, NASA Shuttle missions created new opportunities to develop the speciality called "space neuroscience," and to design Earth-based research to improve techniques and designs for conducting neuroscience experiments in space. As more astronauts of both genders fly in space for longer periods of time, we will be further able to expand our understanding of gravitational forces in space, to learn more about normal function and disease, and to contemplate more accurately the origins of human life.

The central theme of all space life sciences is the shift from Earth's gravity to the microgravity environment of space. All living systems on Earth have evolved in the presence of gravity, and all biological systems have methods and structures to interpret Earth's gravitational force. Space life sciences has produced a significant body of evidence to suggest that gravity directly affects the human body at the cellular level. Over 300 people have experienced life in microgravity, and space scientists have described a wide range of physiological changes, including "facial puffiness," congestion, decreased body weight, and post-flight reduction in aerobic power during exercise, motion sickness during the first three to four days in space, muscle atrophy and weakness.

The experiments that are planned for the 1998 Neurolab Shuttle mission will add significant new information on the mechanisms responsible for some of these changes, so that interventions, called "countermeasures," can be developed to prevent or lessen the effects on crews. Several Neurolab experiments will address factors influencing sleep as well as explore the effects of microgravity on the central nervous system. Animal studies will investigate effects of the space environment on the circadian timing system and examine changes in brain regions that regulate sleep and circadian rhythms. Experiments with the crew will study the relationship between microgravity-induced changes in respiration and sleep and test the efficacy of melatonin as a hypnotic to aid sleep.

A variety of species, including rats, mice, and toad fish, zebra fish, crickets, and snails will be used to investigate the effects of the space environment on the nervous system. Neurolab scientists chose the specie that was considered most appropriate for studying the function to be investigated. Many of the experiments using animals complement studies that are to be conducted with the crew. Some of the experiments will give us greater understanding of the biochemical, cellular, and molecular mechanisms that underlie the phenomena to be studied in the human subjects, while other animal studies will focus on the role of gravity in the development of the nervous system.

Space neuroscience experiments are challenging scientists to rethink scientific methodology and to come up with new techniques because of the unique characteristics that define how experiments can be done on very small samples, the limitations of time and work space on the spacecraft, and the difficulties inherent in training astronauts to be pilots of the spacecraft and scientists at the same time.

The Neurolab shuttle mission science payload focuses on the effects of weightlessness and other aspects of the space environment on six areas of the central nervous system: (i) developmental and cellular neurobiology, (ii) vestibular function, (iii) spatial orientation and visuo-motor performance, (iv) autonomic nervous system regulation, (v) sleep and circadian rhythms, and (vi) learning and behavior.