Department for Animal Physiology, Institute for Zoology, Biocenter Cologne, University of Cologne, Zülpicher Strasse 47b, 50674, Cologne, Germany.
Department of Biomedical Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV, 25704, USA.
J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2019 Apr;205(2):253-270. doi: 10.1007/s00359-019-01334-4. Epub 2019 Apr 11.
Force feedback from Campaniform sensilla (CS) on insect limbs helps to adapt motor outputs to environmental conditions, but we are only beginning to reveal the neural control mechanisms that mediate these influences. We studied CS groups that affect control of the thoraco-coxal joint in the stick insect Carausius morosus by applying horizontal and vertical forces to the leg stump. Motor effects of ablation of CS groups were evaluated by recording extracellularly from protractor (ProCx) and retractor (RetCx) nerves. Extracellular recordings showed that the effects of stimulating the sensilla were consistent with their broad ranges of directional sensitivity: for example, RetCx firing in response to posterior bending could be reduced by ablating several groups of trochanteral CS, whereas ablation of tibial and femoral sensilla had little effect. In contrast, ProCx motor neuron activity upon anteriorly directed stimuli was affected mainly by ablating a single CS group (G2). Dye fills of trochanteral, femoral and tibial CS groups with fluorescent dyes revealed a common projection pattern with little group specificity. These findings support the idea that the influences of CS feedback are determined by the activities of pre-motor interneurons, facilitating fast and task-dependent adaptation to changing environmental conditions.
昆虫附肢上的杯形感觉器（CS）产生的力反馈有助于使运动输出适应环境条件，但我们才刚刚开始揭示介导这些影响的神经控制机制。我们通过向昆虫的腿残端施加水平和垂直力来研究影响 stick insect Carausius morosus 胸-腹关节控制的 CS 组。通过从伸展肌（ProCx）和回缩肌（RetCx）神经上记录的细胞外记录来评估 CS 组消融的运动效应。细胞外记录表明，刺激感觉器的效果与它们广泛的方向敏感性一致：例如，RetCx 对向后弯曲的反应可以通过消融几个转节 CS 组来减少，而消融胫节和股节感觉器几乎没有效果。相比之下，对向前指向的刺激的 ProCx 运动神经元活性主要受到单个 CS 组（G2）的消融的影响。用荧光染料对转节、股节和胫节 CS 组进行的染料填充显示出一种共同的投射模式，几乎没有组特异性。这些发现支持这样一种观点，即 CS 反馈的影响是由运动前神经元的活动决定的，从而促进了对不断变化的环境条件的快速和任务相关的适应。
