NEUROBIOLOGICAL RESPONSES OF FISH TO ALTERED GRAVITY CONDITIONS - A REVIEW

In vertebrates (including man), altered gravitational environments suc h as weightlessness can induce malfunctions of the inner ears, based o n an irregular dislocation of the inner ear otoliths from the correspo nding Sensory epithelia. This dislocation leads to an illusionary tilt , since the otolithic inputs are not confirmed by the other sensory or gans, which results in an intersensory conflict. Vertebrates in the or bit therefore face severe orientation problems. In humans, the interse nsory conflict may additionally lead to a malaise, commonly referred t o as space motion sickness (SMS). During the first days at weightlessn ess, the orientation problems (and SMS) disappear, since the brain dev elops a new compensatory interpretation of the available sensory data. The present review reports on the neurobiological responses - particu larly of fish - observed at altered gravitational states, concerning b ehaviour and neuroplastic reactivities. (C) 1998 Elsevier Science Ltd. All rights reserved.