Multisensory integration in the nonspiking giant interneurons, with special reference to the compensatory oculomotor response

三对非尖峰巨型中间神经元(G1、G2、G3；NGIS)对视觉刺激具有去极化或超极化的分级电位(Okada和Yamaguchi，1989)。在目前的实验中，我们得到了以下结果：NGIS在黑暗中以去极化和超极化的梯度电位响应身体向IPSI和对侧倾斜。在同侧去定向肌的动物中，所有NGI只对对侧向下倾斜有超极化反应，而在对侧去定向肌的动物中，它们只对同侧向下倾斜有去极化反应。在双侧切除的动物中，在黑暗中，NGI对身体倾斜没有反应，但在头顶灯存在的情况下，它们分别对身体倾斜到同侧和对侧表现出去极化和超极化的电位。视觉反应的幅度与身体倾斜产生的地心反应的幅度有关。另一方面，在双侧定向肌切除的动物中，NGIS以去极化和超极化的梯度电位向上反应，并在黑暗中对底物绕身体纵轴倾斜做出反应。对侧行走腿的电位极性与运动方向之间的关系与同侧行走腿的相反。在完整的动物中，NGIS对黑暗中的腿部运动几乎没有反应。这些结果表明，NGIS整合了来自眼睛、静止囊和腿部本体感受器的感觉输入，来自左右感觉器官的相同或不同形式的感觉输入之间的相互作用增强了NGIS作为代偿性动眼神经系统中的前运动神经元的方向敏感性。

Three pairs of nonspiking giant interneurons (G1, G2, G3 ; NGIs) respond with depolarizing or hyperpolarizing graded potentials to visual stimuli (Okada and Yamaguchi, 1989). In the present experiments, we obtained the following results.The NGIs respond with depolarizing and hyperpolarizing graded potentials to body tilt in roll to the ipsi- and contralateral sides in the dark. In ipsilaterally statocystectomized animals, all the NGIs respond with hyperpolarizing potentials only to the contralateral side-down tilt, whereas in contralaterally statocystectomized animals, they respond with depolarizing potentials only to the ipsilateral side-down tilt. In bilaterally statocystectomized animals, none of the NGIs respond to body tilt in the dark, but in the presence of a overhead light, they exhibit depolarizing and hyperpolarizing potentials in response to body tilt to the ipsi- and contralateral sides, respectively. The amplitude of visual responses varies in association with the amplitude of the geotactic response produced by body tilt. On the other hand, in bilaterally statocystectomized animals the NGIs respond with depolarizing and hyperpolarizing graded potentials to upward and respond to substrate tilt about the longitudinal axis of the body in the dark. Relationships between the polarity of potential and the direction of movement in the contralateral walking legs were just opposite to those in the ipsilateral walking legs. In intact animals the NGIs hardly respond to leg movements in the dark.These results indicate that the NGIs integrate the sensory inputs from eyes, statocysts, and leg proprioceptors and that the interaction between sensory inputs from the left and right sensory organs with either the same modality or with different modalities enhance the directional sensitivity of NGIs as premotoneurons in the compensatory oculomotor system.