Comparative Neuromechanics

陆地哺乳动物的体型多种多样，其中最大的大象比最小的地鼠大几百万倍。由于体型大小不同，大型动物和小型动物面临着截然不同的身体挑战。例如，如果一头大象摔倒，它可能会受到重伤，而类似的摔倒对于一只地鼠来说可能是微不足道的。为了了解大型和小型动物在面对不同的身体挑战时如何协调它们的运动，我们必须首先确定大小如何影响潜在的生理控制机制。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比例。我们的一般假设是，感觉运动系统的响应性和分辨率之间存在折衷，随着身体尺寸的增加，这种折衷变得更加尖锐。我们最近通过确定身体大小和最大神经传导速度之间的关系来检验这一假说。一个令人兴奋的发现是，从地鼠到大象，神经传递信息的最大速度几乎是恒定的。因此，大型动物承受着相对较长的传导延迟。在这里，我们建议扩展这项早期的工作，以测试我们的一般假设，因为它适用于脊髓反射路径的潜伏期和周围神经的解剖。我们还提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，它们必须越来越多地依赖感觉运动预测来维持感觉运动性能。这项拟议的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。许多对动物的成功至关重要的任务都需要有效的神经肌肉控制，包括运动、摄食和繁殖--了解它的伸缩性有望为哺乳动物的行为、生态和进化提供相当大的洞察力。

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.