Comparative Neuromechanics

陆生哺乳动物的体型差异很大，最大的大象比最小的鼩鼱要大几百万倍。由于体型的不同，大型动物和小型动物面临的体能挑战也大不相同。例如，如果一头大象摔倒，它可能会受到严重伤害，而对鼩鼱来说，类似的摔倒可能无关紧要。为了理解小型动物和大型动物在面对不同的生理挑战时是如何协调运动的，我们必须首先确定体型是如何影响生理控制的机制的。这项研究计划的长期目标是了解陆生哺乳动物神经肌肉控制的尺度。我们的一般假设是，感觉运动系统的反应性和分辨力之间存在一种妥协，这种妥协随着体型的增加而变得更加尖锐。我们最近通过确定体型和最大神经传导速度之间的关系来验证这一假设。一个令人兴奋的发现是，从鼩鼱到大象，神经传递信息的最高速度几乎是恒定的。因此，大型动物承受着相对较长的传导延迟。在这里，我们建议扩展这一早期工作，以测试我们的一般假设，因为它适用于脊髓反射通路的潜伏期和周围神经的解剖。我们还建议研究我们认为这些发现最重要的含义——随着大型动物延迟的增加，它们必须越来越依赖于感觉运动预测来维持感觉运动表现。这项拟议研究的总体意义在于，它将为神经肌肉控制系统的组织和功能提供基本的见解。有效的神经肌肉控制对于动物成功的许多重要任务都是必需的，包括运动、进食和繁殖——对其规模的理解有望为哺乳动物的行为、生态学和进化提供相当大的见解。

Terrestrial mammals span a wide range of sizes, with the largest elephant being several million times more massive than the smallest shrew. As a consequence of their size, large and small animals experience very different physical challenges. If an elephant falls, for example, it risks grave injury, while a similar tumble for a shrew would likely be inconsequential. To understand how small and large animals coordinate their movement in the face of differing physical challenges like these, one must first determine how size influences the mechanisms underlying physiological control. The long-term objective of this research program is to understand the scaling of neuromuscular control in terrestrial mammals. Our general hypothesis is that there is a compromise between the responsiveness and resolution of sensorimotor systems that becomes more acute with increases in body size. We recently tested this hypothesis by determining the relationship between body size and maximum nerve conduction velocity. One exciting finding was that from shrews to elephants, the maximum speed at which nerves can conduct information is nearly constant. Consequently, large animals are burdened with relatively long conduction delays. Here we propose to expand on this earlier work to test our general hypothesis as it applies to the latency of spinal reflex pathways and the anatomy of peripheral nerves. We are also proposing to study what we consider the most important implication of these findings - as delays increase in larger animals, they must increasingly depend upon sensorimotor prediction to maintain sensorimotor performance. The general significance of this proposed research is that it will provide fundamental insight into the organization and function of neuromuscular control systems. Effective neuromuscular control is required for many tasks essential to an animal's success including locomotion, feeding and reproduction-an understanding of its scaling promises to provide considerable insight into mammalian behaviour, ecology and evolution.