Kawakami I, Shiraishi S, Tsuda M
Department of Life Science, Himeji Institute of Technology, Harima Science Garden City, Akoh-gun, Hyogo, 678-1297 Japan.
J Biol Phys. 2002 Sep;28(3):549-59. doi: 10.1023/A:1020314116923.
Ascidians are lower chordates and their simple tadpole-like larvae share a basic body plan with vertebrates. Newly hatched larvae show no response to a stimulus of light. 4 h after hatching, the larvae were induced to swim upon a step-down of light and stop swimming upon a step-up of light. At weaker intensity of light, the larvae show the same response to a stimulus after presentation of repeated stimuli. When intensity of actinic light was increased, the larvae show sensitization and habituation of the swimming response to a stimulus after repeated stimuli of step-down and step-up of the light. Between 2 h 20 min and 3 h 40 min after hatching the larvae did not show any response to the first stimulus, but after several repeatedstimuli they show swimming response to a step-down of light. A repeated series of stimulus cause sensitization. Between 4 h and 7 h after hatching, the larvae show photoresponse to the first stimulus, but after several repetition of the stimuli, the larvae could not stop swimming to a stimulus of a step-up of the actinic light. A repeated series of stimulus cause greaterhabituation. Both sensitization and habituation depend upon intensity ofactinic light.
海鞘是低等脊索动物，它们类似蝌蚪的简单幼虫与脊椎动物有着基本的身体结构。刚孵化出的幼虫对光刺激没有反应。孵化后4小时，幼虫在光照强度减弱时被诱导游泳，在光照强度增强时停止游泳。在较弱的光照强度下，幼虫在反复受到刺激后对刺激表现出相同的反应。当光化光强度增加时，幼虫在光强度反复减弱和增强刺激后，对刺激的游泳反应表现出敏感化和习惯化。在孵化后2小时20分钟至3小时40分钟之间，幼虫对第一次刺激没有任何反应，但在几次反复刺激后，它们对光强度减弱表现出游泳反应。一系列重复刺激会导致敏感化。在孵化后4小时至7小时之间，幼虫对第一次刺激表现出光反应，但在几次刺激重复后，幼虫无法停止对光化光强度增强刺激的游泳。一系列重复刺激会导致更大程度的习惯化。敏感化和习惯化都取决于光化光的强度。
