魚の背光反射行動と小脳活動に対する無重力効果

概要

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Behavior and cerebellar electrical activity of a carp (25cm in size) were observed during free-fall hypogravity using a balloon microgravity system which was recently developed by Nishimura and his group. The carp's behavior was taken in 8mm films during the free fall and the cerebellar activity was telemetered during the whole flight. A fish chamber was so designed as to keep the animal healthy for more than 10 hours and to induce the dorsal light tilt reaction (DLTR) of the carp in the midst of free-fall. Two days before the launch, the chamber was set into the rocket-shaped air-tight capsule. The chamber function was supported by another device throughout the stay on the ground. The balloon microgravity system worked perfectly with minimal spinning and pitching and 20-seconds hypogravity of 10^<-3>-10^<-2>G was obtained from the onset of free-fall to the parachute opening. The film recovered showed that the carp, standing upright along the gravity force, tilted her body axis to receive the light on her back (DLTR) during the free fall, indicating that the posture would be completely controlled by light under a hypogravic state. A computer analysis made for the cerebellar activity revealed that the power spectrum had increased remarkably during the free fall, at the frequency ranges of around 10Hz and 25-30Hz.
宇宙航空研究開発機構の論文