Burrows M
Department of Zoology, University of Cambridge, England.
J Exp Biol. 1989 Sep;146:209-27. doi: 10.1242/jeb.146.1.209.
The processing of mechanosensory signals responsible for the reflex adjustment of the posture or movement of the legs of the locust is described in terms of the actions and connections of identified neurones. Signals can be followed from the major classes of exteroceptors of a leg, through their various integrative stages in the central nervous system to their emergence as specific patterns in known motor neurones. Particular emphasis is placed on the integrative roles of two classes of local interneurones. The spiking local interneurones map the leg as a series of overlapping receptive fields and reverse the sign of the afferent input. The nonspiking local interneurones control the output of the motor neurones by the graded release of chemical transmitter and can adjust the gain of a local reflex depending on the position and movements of the joints of that leg. The reflex movements of one leg must not impair the stability of the animal and must therefore be influenced by events at the other legs. Populations of intersegmental interneurones convey sensory information from one segment to another to ensure such coordination. These interneurones do not produce stereotyped intersegmental reflexes but, instead, alter the performance of a local reflex in a distant leg by making synaptic connections with nonspiking local interneurones. These connections change the effectiveness of the outputs to the motor neurones and consequently the local reflex. The local interneurones therefore play a crucial role both in the production of local reflexes and in the integration of these actions with the movements of the other legs.
本文根据已识别神经元的作用和连接，描述了负责蝗虫腿部姿势或运动反射调节的机械感觉信号的处理过程。信号可以从腿部主要的外部感受器类别开始追踪，经过它们在中枢神经系统中的各个整合阶段，直至在已知运动神经元中以特定模式出现。文中特别强调了两类局部中间神经元的整合作用。发放脉冲的局部中间神经元将腿部映射为一系列重叠的感受野，并反转传入输入的信号。不发放脉冲的局部中间神经元通过化学递质的分级释放来控制运动神经元的输出，并可根据该腿部关节的位置和运动来调整局部反射的增益。一条腿的反射运动绝不能损害动物的稳定性，因此必须受到其他腿部事件的影响。节间中间神经元群体将感觉信息从一个节段传递到另一个节段，以确保这种协调。这些中间神经元不会产生刻板的节间反射，而是通过与不发放脉冲的局部中间神经元建立突触连接，改变远处腿部局部反射的表现。这些连接改变了对运动神经元输出的有效性，从而改变了局部反射。因此，局部中间神经元在局部反射的产生以及这些动作与其他腿部运动的整合中都起着至关重要的作用。
