Central control mechanisms of motor patterns by multimodal inputs.

本文研究了美洲大蠊多模式中间神经元调节运动模式的形态和生理特性。大脑局部中间神经元整合了来自颈、触角和腿上的各种机械感受器以及复眼和眼球中的光感受器的信号。激活这个小神经元，在接受光感受器输入的大的二级枕叶神经元中产生兴奋性突触后电位(EPSPS)。药理和免疫组织化学实验表明，该神经元为GABA能神经元。共鉴定出8种下行中间神经元。大多数下降的神经元对一阵风吹向宫颈和触角的反应是一连串的棘波。四种类型的神经元对两个顶盖之一或两个顶盖的光照反应表现出对棘波放电的抑制，而其余四种类型的神经元对顶盖光照几乎没有反应。一些神经元的特征是对复眼前面移动的一点光有强烈的反应。电刺激一种特定的下行中间神经元，可在胸段中间神经元引起EPSP，并在支配腿部肌肉的一些运动神经元上产生一些棘波。胸椎间神经元较多，可被颈髓刺激兴奋，但被耳廓照射抑制。本研究中考察的各种中间神经元发出的主要信息似乎与风和触觉刺激有关，因为这种刺激通常会在神经元中产生一系列尖峰。然而，这种强烈的反应常常被眼皮细胞的光照有效地抑制。据推测，在运动过程中，各种外部和内部的机械感受器被持续地刺激，这将在许多中间神经元中引起尖峰放电，而眼球光条件的变化将调制它们的尖峰放电。这可能导致逃逸运动过程中由眼球光条件控制的航向。

Morphological and physiological properties of multimodal interneurons modulating the motor patterns of locomotion in the American cockroach Periplaneta americana have been examined. A cerebral local interneuron integrated signals from various mechanoreceptors on the cerci, antennae and legs and from photoreceptors in the compound eyes and ocelli. Activation of this small neuron produced excitatory postsynaptic potentials (EPSPs) in the large second-order ocellar neurons which receive input from photoreceptors. Pharmacological and immunohistochemical experiments suggested that this neuron was GABAergic. Eight types of descending interneurons were identified. Most descendingneurons responded with a train of spikes to a puff of wind to the cerci and antennae. Four types of neurons shows an inhibition of spike discharges in response to illumination of either of two ocelli or both, while remaining four showed little response to the ocellar illumination. Some neurons were characterized by their strong responses to a spot of light moving in front of the compound eyes. Electrical stimulation of a particular descending interneurons caused EPSPs in a thoracic interneurons and a few spikes in some motoneurons innervating leg muscles. There were many thoracic interneurons which were excited by cercal stimulation and inhibited by ocellar illumination. Major information signaled by various interneurons examined in the present study appears to concern wind and tactile stimuli, because such stimuli usually produced a train of spikes in the neurons. However, such a strong response was often effectively suppressed by illumination of the ocelli. It is supposed that various external and internal mechanoreceptors are continuously stimulated during locomotion, which would evoke spikes in many interneurons, and changes in ocellar light conditions would modulate their spike discharges. This may result in course control by ocellar light condition during escape locomotion.