[BEHAVIOURAL AND FUNCTIONAL VESTIBULAR DISTURBANCES AFTER SPACE FLIGHT. 1. MAMMALS]

The review contains data on functional changes in mammals caused by changes in the operation of vestibular system after space flight. These data show that the vestibular system of mammals responds to weightlessness challenge differently at various ontogenetic stages. Orbital space flight conditions have a weak effect on the developing vestibular system during embryonic period. The weightlessness conditions have rather beneficial effect on development of the fetuses. During the early postnatal period, when optimal sensory-motor tactics are created, the prolonged stay under conditions of space flight leads to development of novel, "extraterrestrial" sensory-motor programs that can be fixed in CNS, apparently, for the whole life. In adult individuals after landing essential vestibular changes and disturbances may occur that depend on the spaceflight duration. The adult organism must simultaneously solve two contradicting problems--it should adapt to weightlessness conditions, and should not adapt to them to pass the process of readaptation after returning easier. Thus, individuals must protect themselves against weightlessness influence to keep the intact initial state of health. The protection methods against weightlessness ought to be adjusted according to the duration of space flight. It should be mentioned that not all functional changes registered in adult individuals after landing can be adequately explained. Some of these changes may have chronic or even pathological character. The question of necessity to examine the influence of weightlessness on an aging (senile) organism and on its vestibular system is raised for the first time in this review. In our opinion the development of space gerontology, as a special branch of space biology and medicine, is of undoubted interest, and in the future it may be of practical importance especially taking into account the steadily growing age of cosmonauts (astronauts).