Taddei-Ferretti C, Chillemi S, Cotugno A
Exp Biol. 1987;46(3):133-40.
It has been hypothesized that the mechanism responsible for the rhythmic contraction-relaxation activity of Hydra attenuata is oscillatory. This nature is confirmed by the possibility of obtaining the suppression of overt behaviour by high frequency photic stimulation, which entrains the behaviour at a phase different from that giving rise to overt activity. Such a triggering mechanism should be structured as two different subsystems, mutually inhibiting. Also each one rebounds after the received inhibition in such a way that the active phase of each of them corresponds to the inhibited phase of the other one. This functional structure is argued from: 1. the existence of two triggering zones responsible for the contraction and relaxation phases; 2. the existence of a difference between the bioelectric potentials which reflect the activity of such triggering zones; 3. the opposite trend of these two bioelectric potentials at all phases in undisturbed conditions, and 4. the opposite direction of the variation of such bioelectric potentials as post-effects of either photic or electric stimulation, which follow the effects in the same direction undergone by the potentials themselves.
据推测，细螅有节奏的收缩-舒张活动的机制是振荡性的。高频光刺激能够抑制明显行为，且这种抑制能使行为在与引发明显活动的相位不同的相位上同步，这证实了这种性质。这样一种触发机制应构建为两个相互抑制的不同子系统。而且每个子系统在受到抑制后都会反弹，使得它们各自的活跃相位与另一个的抑制相位相对应。这种功能结构基于以下几点得到论证：1. 存在两个分别负责收缩期和舒张期的触发区；2. 反映此类触发区活动的生物电势存在差异；3. 在未受干扰的情况下，这两种生物电势在所有相位都呈相反趋势；4. 作为光刺激或电刺激的后效应，此类生物电势的变化方向相反，且与电势本身所经历的相同方向的效应一致。
