Braking slows passive flexion during goal-directed movements of a small limb.
Braking slows passive flexion during goal-directed movements of a small limb.
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在小肢体的目标导向运动过程中，制动会减慢被动屈曲速度。
DOI：
10.1016/j.cub.2022.08.052
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Rossoni S
中科院分区：
文献类型：
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作者：
Rossoni S
动物附肢的运动是由外力和内在力决定的。外在力包括重力或摩擦力，1,2 而内在力是由主动肌肉收缩或被动肌肉骨骼元件产生的。3,4 对于昆虫四肢等轻量附属物，运动更多地依赖于内在力而不是外在力。5,6 事实上，昆虫四肢的被动运动可能很大，并且反对或有助于关节屈曲、伸展或两者兼而有之。4然而，被动特性如何有助于昆虫以目标为导向的肢体运动，例如目标到达和移动搜索,7,8,9,10仍不清楚。在这里，我们展示了螳螂通过使用猛禽前肢进行有针对性的接触和搜索物体，利用制动来减缓股胫骨（FTi）关节的被动弯曲。在大多数情况下，胫骨弯曲可确保前肢接触物体。当前肢错过物体并继续向下轨迹或在定向搜索运动期间，这种胫骨弯曲尤其明显。我们通过将切除肢体的被动运动与足部消融和肌肉刺激相结合来描述 FTi 关节的被动特性。这些实验表明，胫骨屈肌-足复合体的被动特性是在切除的肢体中产生胫骨屈曲的主要结构元件。然而，在到达和搜索过程中，胫骨屈曲比预期更慢且更小。这是由于制动阻碍了被动屈曲，从而降低了胫骨屈曲的幅度和速度。制动延迟被动运动是一种新颖的行为相关控制策略，用于轻量肢体（例如昆虫）的目标导向运动。
The movements of animal appendages are determined by extrinsic and intrinsic forces. Extrinsic forces include gravity or friction,1,2whereas intrinsic forces are generated by active muscle contraction or passive musculoskeletal elements.3,4For lightweight appendages, such as insect limbs, movements depend more upon intrinsic than extrinsic forces.5,6Indeed, passive movements of insect limbs can be large and oppose or aid joint flexion, extension, or both.4Yet, how passive properties contribute to insects' goal-directed limb movements, such as targeted reaching and searching,7,8,9,10remains unclear. Here, we show that mantids make targeted reaches and searches to objects by using their raptorial forelimbs, employing braking to slow passive flexion of the femoro-tibial (FTi) joint. In most reaches, tibial flexion ensures the forelimb contacts the object. Such tibial flexion is particularly clear when the forelimb misses the object and continues on a downward trajectory or during directed searching movements. We characterize the passive properties of the FTi joint by combining passive movements of excised limbs with apodeme ablations and muscle stimulation. These experiments show that passive properties of the flexor tibiae muscle-apodeme complex are the primary structural element producing tibial flexion in excised limbs. During reaching and searching, however, tibial flexion is slower and smaller than predicted. This is due to braking, which opposes passive flexion, thereby reducing the magnitude and velocity of tibial flexion. Braking retarding passive movements is a novel behaviorally relevant control strategy for the goal-directed movements of lightweight limbs, such as those of insects.