Taddei-Ferretti C, Cordella L
J Exp Biol. 1976 Dec;65(3):737-51. doi: 10.1242/jeb.65.3.737.
We investigated the effect of photic stimulation on the frequency of Hydra attenuata column contractions. We used positive or negative abrupt light transitions, single or repetitive light or darkness pulses, and alternation of light and darkness periods. The main results are: (a) The frequency of the contraction pulse trains (CPTs) varies transiently in response to an abrupt variation of the light intensity. (b) CPTs in progress can be inhibited by different types of photic stimuli. (c) The response time to a single photic stimulus varies during the inter-CPT interval and depends also on the polarity of the stimulus. (d) The CPTs are entrainable with repetitive light stimulation of various frequencies. (e) Long-lasting variations of the frequency of CPTs occur after the end of a repetitive light stimulation. We suggest that the mechanism responsible for the rhythym of column contractions is quite similar to that on which other biological rhythmic phenomena are based.
我们研究了光刺激对细螅柱体收缩频率的影响。我们使用了正向或负向的突然光转换、单次或重复的光或暗脉冲，以及光暗周期交替。主要结果如下：(a) 收缩脉冲序列（CPTs）的频率会随着光强度的突然变化而短暂变化。(b) 正在进行的CPTs可被不同类型的光刺激抑制。(c) 对单个光刺激的反应时间在CPT间隔期间会发生变化，并且还取决于刺激的极性。(d) CPTs可被各种频率的重复光刺激所诱导。(e) 在重复光刺激结束后，CPTs频率会出现持久变化。我们认为，负责柱体收缩节律的机制与其他生物节律现象所基于的机制非常相似。
