Fast or slow? Cellular and molecular adaptations underlying different frequency regimes in spinal motor systems

对于动物生命中最重要的任务：寻找庇护所或食物以及繁殖成功，行动能力是必不可少的。在脊椎动物中，运动是由脊椎回路控制的，脊椎回路产生两侧组织的骨骼肌交替收缩。与行走、跑步、游泳、飞行或爬行等运动方式无关，高度保守的脊髓运动回路，即中央模式发生器(CPGs)，协调支配骨骼肌的运动神经元的活动。虽然在起伏和双或四足移动的动物之间的一般脊髓蓝图回路中的适应导致不同的运动模式，但个别运动模式(例如双侧交替的骨骼收缩)在快速或缓慢移动的动物之间显示出广泛不同的频率范围。这项拟议的研究的目标是在网络、细胞和分子水平上研究使进化上保守的神经元回路产生截然不同的频率机制的机制。响尾蛇为解决这个问题提供了一个独特的机会，因为它们在不同的频率范围内产生两种不同的脊椎行为。脊髓的优势部分产生运动的低频交替肌肉收缩序列(约4-15赫兹)，而脊髓的最尾部产生高频交替模式(约80-120赫兹)，用于发出声学信号(嘎嘎声)。在一种动物身上存在两个功能不同的脊柱系统，这为研究进化适应提供了一个独特的机会，这些适应允许或导致高度不同的频率制度，而不必考虑可能的物种间差异。利用电生理学、药理学、解剖学和分子生物学的方法，本研究的目标是在网络、单细胞和分子水平上阐明这些截然不同的频率机制。一般的假设是，在两种不同的响尾蛇脊椎模式之间保留了一般的脊髓网络组织，细胞适应导致了不同的频率区域。这项研究将有助于阐明具有共同进化起源的神经元回路如何被修改以表达不同的行为。摘要：利用响尾蛇中存在的慢(运动)和快(嘎嘎声系统)脊髓运动系统，拟议的研究的目标是了解导致具有共同进化起源的神经元回路中不同频率机制的潜在机制。

The ability to move is essential for the most important tasks in an animals life: the search for shelter or food and reproductive success. In vertebrates, locomotion is governed by spinal circuits that generate alternating contractions of bilaterally organized skeletal muscles. Independent of locomotor style, such as walking, running, swimming, flying or crawling, highly conserved spinal locomotor circuits, i.e., central pattern generators (CPGs), coordinate the activity of motoneurons innervating the skeletal muscles. While adaptations in the general spinal blueprint circuit between undulating and bi- or quadrupedal moving animals lead to different locomotor patterns, individual motor patterns (e.g. bilaterally alternating skeletal contractions) display widely diverging ranges of frequencies between fast or slowly moving animals. The goal of the proposed study is to investigate, at a network, cellular and molecular level, the mechanisms that enable evolutionarily conserved neuronal circuits to generate widely different frequency regimes. Rattlesnakes offer a unique opportunity to address this question since they produce two different spinal behaviors at distinct frequency ranges. The predominant part of the cord generates low frequency alternating muscle contraction sequences for locomotion (ca. 4-15Hz), whereas the most caudal part of the spinal cord generates high frequency alternating patterns (ca. 80-120 Hz) for acoustic signaling (rattling). The presence of two functionally different spinal systems in one animal provides a unique opportunity to investigate evolutionary adaptations that enable or cause highly diverging frequency regimes without having to consider possible interspecies differences. Using electrophysiological, pharmacological, anatomical and molecular methods, the goal of this proposed study is to elucidate the mechanisms responsible for these widely different frequency regimes at a network, single cell, and molecular level. The general hypothesis is that the general spinal network organization is retained between the two different rattlesnake spinal patterns, and that cellular adaptations lead to the different frequency regimes. This study will help shed light on how neuronal circuits that share a common evolutionary origin can be modified to express different behaviors.Summary: Taking advantage of the presence of slow (locomotion) and fast (rattling system) spinal motor systems in the rattlesnake, the goal of the proposed study is to understand the underlying mechanisms leading to different frequency regimes in neuronal circuits that share a common evolutionary origin.