Central control mechanisms of motor patterns by multimodal inputs.

研究了调节美洲大蠊运动模式的多模态中间神经元的形态和生理特性。一个局部的大脑中间神经元整合来自尾骨、触角和腿上的各种机械感受器以及复眼和眼内的光感受器的信号。这个小神经元的激活在接收光感受器输入的大的二级胞状神经元中产生兴奋性突触后电位（EPSPs）。药理和免疫组化实验表明该神经元具有gaba能。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的触须和触角产生一连串的尖峰反应。四种类型的神经元对两个眼细胞中的任何一个或两个眼细胞的照明都表现出抑制，而其余四种神经元对眼细胞的照明几乎没有反应。一些神经元的特点是对复眼前移动的光点有强烈的反应。电刺激某一特定的下行中间神经元可引起胸椎中间神经元的EPSPs和一些支配腿部肌肉的运动神经元的少量峰值。胸椎中间神经元较多，在颈刺激下兴奋，在胞内光照下抑制。在本研究中，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，因为这些刺激通常在神经元中产生一系列的尖峰。然而，这种强烈的反应常常被光阱的照明有效地抑制。据推测，在运动过程中，各种外部和内部的机械感受器不断受到刺激，从而在许多中间神经元中引起尖峰放电，而室内光照条件的变化可以调节它们的尖峰放电。这可能导致逃逸运动过程中由室内光线条件控制的过程。

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.