The vestibular nuclei and circuitry exist to monitor gravitational changes. How will its development be affected by microgravity? Without the input from the inner ear, how will vestibular circuits develop? This is the focus of experiments by Dr. Jacqueline Raymond. Dr. Ken Kosik's experiment will examine the hippocampus, the part of the brain critical for spatial location and learning. How will this part of the brain be affected as it develops without the spatial information from gravity sensors?
Dr. Kerry Walton demonstrated on Earth that rats suspended by their tails (thereby removing the loading forces on the hindlimb) when they were 8-14 days old, developed abnormal walking patterns that persisted into adulthood. This suggested that gravitational loading may be critical for the normal development of motor pathways. These findings will be extended to space on Neurolab. Similarly, since much of the loading on nmuscles comes from gravitational forces, how will muscles develop without gravity? Dr. Dan Riley will study the neuromuscular system in both an anti-gravity (soleus) and non anti-gravity (extensor digitorum longus) muscle. This will show not only the effects of microgravity on the muscle, but also whether any abnormalities occurring during development in space will persist on the ground. Dr. Ken Baldwin will also study muscle, but will investigate the effects of thyroid hormone in addition to gravity on the production of key muscle protein components (myosin heavy chains).
The experiment from Dr. Tsuyoushi Shimizu makes a link with the autonomic team. He is studying the blood pressure receptors in the aorta and whether they will develop normally without gravity. Dr. Richard Nowakowski is looking at a very fundamental question, whether the proliferation of nerves (a necessary condition for normal development) is affected by gravity. This could have major implications for the other experiments in this team.