演題番号 : P3-q16
稲田 健吾 / Kengo Inada:1 高坂 洋史 / Hiroshi Kohsaka:2 高須 悦子 / Etsuko Takasu:2 能瀬 聡直 / Akinao Nose:1,2
1:東京大院・新領域・複雑理工 / Dept Comp Sci Eng, Univ of Tokyo, Tokyo 2:東京大院・理・物 / Dept Phys, Univ of Tokyo, Tokyo
Drosophila larval crawling is elicited by coordinated propagation of neural activity within the nervous system, providing an ideal system to analyze the spatiotemporal dynamics of neural activity in an intact animal. During crawling, local neural activity is propagated along the entire body from the posterior to anterior segments in about 1 sec. To dissect the temporal dynamics of the propagation on the timescale of milliseconds, we generated a transgenic line expressing Natronomonas pharaonis halorhodopsin (NpHR), a light-driven chloride pump, and analyzed the influence of temporal inhibition of neural activity in different subsets of neurons by GAL4-UAS system. First, we expressed NpHR in all motor neurons and tested the effectiveness of NpHR by applying a continuous light stimulus (several seconds) on crawling larvae. The light stimulus ceased the locomotion by completely loosening the muscles, showing that NpHR is effective in Drosophila larvae. Next, we studied the effects of brief inhibition of motor neurons during locomotion by applying pulsed illumination (800 msec.). We asked if the state of the propagation is retained during the light-elicited inhibition for 800 msec. If so, the locomotion will restart from the site where locomotion was inhibited, when the light is off. If not, the locomotion will restart from other segments, possibly elicited by higher order circuits controlling locomotion whose propagation occurs independent of the activity of motor neurons. We found that after pulsed optical inhibition of motor neurons (and subsets of GABAergic neurons) during peristaltic locomotion, the propagation restarted from the segment at which the propagation was temporally blocked. The observation suggests the existence of information retention system within larval neural networks.