Hess D, Büschges A
Department of Animal Physiology, Faculty of Biology, University of Kaiserslautern, 67653 Kaiserslautern, Germany.
J Neurophysiol. 1999 Apr;81(4):1856-65. doi: 10.1152/jn.1999.81.4.1856.
Interjoint reflex function of the insect leg contributes to postural control at rest or to movement control during locomotor movements. In the stick insect (Carausius morosus), we investigated the role that sensory signals from the femoral chordotonal organ (fCO), the transducer of the femur-tibia (FT) joint, play in patterning motoneuronal activity in the adjacent coxa-trochanteral (CT) joint when the joint control networks are in the movement control mode of the active behavioral state. In the active behavioral state, sensory signals from the fCO induced transitions of activity between antagonistic motoneuron pools, i.e., the levator trochanteris and the depressor trochanteris motoneurons. As such, elongation of the fCO, signaling flexion of the FT joint, terminated depressor motoneuron activity and initiated activity in levator motoneurons. Relaxation of the fCO, signaling extension of the FT joint, induced the opposite transition by initiating depressor motoneuron activity and terminating levator motoneuron activity. This interjoint influence of sensory signals from the fCO was independent of the generation of the intrajoint reflex reversal in the FT joint, i.e., the "active reaction," which is released by elongation signals from the fCO. The generation of these transitions in activity of trochanteral motoneurons barely depended on position or velocity signals from the fCO. This contrasts with the situation in the resting behavioral state when interjoint reflex action markedly depends on actual fCO stimulus parameters, i.e., position and velocity signals. In the active behavioral state, movement signals from the fCO obviously trigger or release centrally generated transitions in motoneuron activity, e.g., by affecting central rhythm generating networks driving trochanteral motoneuron pools. This conclusion was tested by stimulating the fCO in "fictive rhythmic" preparations, activated by the muscarinic agonist pilocarpine in the otherwise isolated and deafferented mesothoracic ganglion. In this situation, sensory signals from the fCO did in fact reset and entrain rhythmic activity in trochanteral motoneurons. The results indicate for the first time that when the stick insect locomotor system is active, sensory signals from the proprioceptor of one leg joint, i.e., the fCO, pattern motor activity in an adjacent leg joint, i.e., the CT joint, by affecting the central rhythm generating network driving the motoneurons of the adjacent joint.
昆虫腿部的关节间反射功能有助于在静止时进行姿势控制或在运动过程中进行运动控制。在竹节虫（Carausius morosus）中，我们研究了来自股骨弦音器（fCO）（即股骨 - 胫骨（FT）关节的感受器）的感觉信号，在关节控制网络处于主动行为状态的运动控制模式时，对相邻的髋 - 转节（CT）关节中运动神经元活动模式的作用。在主动行为状态下，来自fCO的感觉信号诱导拮抗运动神经元池之间的活动转换，即转子提肌运动神经元和转子降肌运动神经元。因此，fCO的伸长，表明FT关节的屈曲，终止了降肌运动神经元的活动并启动了提肌运动神经元的活动。fCO的松弛，表明FT关节的伸展，通过启动降肌运动神经元的活动并终止提肌运动神经元的活动，诱导了相反的转换。来自fCO的感觉信号的这种关节间影响独立于FT关节内关节反射反转的产生，即“主动反应”，它由来自fCO的伸长信号释放。转节运动神经元活动的这些转换的产生几乎不依赖于来自fCO的位置或速度信号。这与静止行为状态下的情况形成对比，在静止行为状态下，关节间反射作用明显依赖于实际的fCO刺激参数，即位置和速度信号。在主动行为状态下，来自fCO的运动信号显然触发或释放运动神经元活动中由中枢产生的转换，例如，通过影响驱动转节运动神经元池的中枢节律产生网络。通过在“虚构节律”制剂中刺激fCO来检验这一结论，该制剂由毒蕈碱激动剂毛果芸香碱在原本分离且去传入神经的中胸神经节中激活。在这种情况下，来自fCO的感觉信号实际上确实重置并夹带了转节运动神经元的节律性活动。结果首次表明，当竹节虫运动系统处于活动状态时，来自一个腿部关节的本体感受器（即fCO）的感觉信号，通过影响驱动相邻关节运动神经元的中枢节律产生网络，来调控相邻腿部关节（即CT关节）的运动活动模式。
