How do treadmill speed and terrain visibility influence neuromuscular control of guinea fowl locomotion?
How do treadmill speed and terrain visibility influence neuromuscular control of guinea fowl locomotion?
复制标题
DOI：
10.1242/jeb.104646
复制
发表时间：
2015-10
期刊：
影响因子：
--
通讯作者：
Daley MA
中科院分区：
文献类型：
--
作者：
Gordon JC;Rankin JW;Daley MA
运动控制机构必须灵活地适应预期和意外的地形变化，以保持运动并避免跌倒。最近的研究表明，地面鸟类改变运动提前地上的障碍，但不是跑步机的障碍，这表明在使用预期控制的上下文相关的转变。我们假设地上和跑步机障碍谈判之间的差异与视觉感官信息的差异有关，这会影响执行预期动作的能力。我们探讨了两种可能的解释：（1）以前的跑步机障碍物可能在视觉上无法察觉，因为它们与踏板的对比度较低，（2）与跑道障碍物相比，跑步机障碍物可见的时间较短，限制了视觉调整的时间。为了研究这些因素，我们测量了在两种速度（0.7和1.3 m s-1）和三种地形条件下跑步机运动过程中，珍珠鸡（Numida musagris，N=6）的8块后肢肌肉的肌电图活动：（i）水平，（ii）重复5 cm低对比度障碍物（<10%对比度，黑色/黑色），和（iii）重复5 cm高对比度障碍物（>90%对比度，黑色/白色）。 我们假设，当观察障碍物的时间较长时，（1）高对比度障碍物和（2）跑步机速度较慢时，肌肉活动的预期变化会更高。我们发现，跑步机的速度显着影响障碍谈判策略，但障碍对比没有。在较慢的速度，我们观察到更早和更大的预期增加肌肉活动和运动时序的变化。我们讨论了可能的视觉解释所观察到的上下文相关的预期策略的使用。总结：珍珠鸡（努米达agris）显示速度依赖性的变化，在障碍谈判过程中的神经肌肉控制，其特征在于更大的依赖于预期的调制和步幅到步幅的神经调节在低速，转向前馈激活和内在的机械稳定性在高速。
Locomotor control mechanisms must flexibly adapt to both anticipated and unexpected terrain changes to maintain movement and avoid a fall. Recent studies revealed that ground birds alter movement in advance of overground obstacles, but not treadmill obstacles, suggesting context-dependent shifts in the use of anticipatory control. We hypothesized that differences between overground and treadmill obstacle negotiation relate to differences in visual sensory information, which influence the ability to execute anticipatory manoeuvres. We explored two possible explanations: (1) previous treadmill obstacles may have been visually imperceptible, as they were low contrast to the tread, and (2) treadmill obstacles are visible for a shorter time compared with runway obstacles, limiting time available for visuomotor adjustments. To investigate these factors, we measured electromyographic activity in eight hindlimb muscles of the guinea fowl (Numida meleagris, N=6) during treadmill locomotion at two speeds (0.7 and 1.3 m s−1) and three terrain conditions at each speed: (i) level, (ii) repeated 5 cm low-contrast obstacles (<10% contrast, black/black), and (iii) repeated 5 cm high-contrast obstacles (>90% contrast, black/white). We hypothesized that anticipatory changes in muscle activity would be higher for (1) high-contrast obstacles and (2) the slower treadmill speed, when obstacle viewing time is longer. We found that treadmill speed significantly influenced obstacle negotiation strategy, but obstacle contrast did not. At the slower speed, we observed earlier and larger anticipatory increases in muscle activity and shifts in kinematic timing. We discuss possible visuomotor explanations for the observed context-dependent use of anticipatory strategies. Summary: Guinea fowl (Numida meleagris) show speed-dependent shifts in neuromuscular control during obstacle negotiation, characterized by a greater reliance on anticipatory modulation and stride-to-stride neural adjustments at slow speed, shifting towards feedforward activation and intrinsic mechanical stability at high speed.