A Leg-Local Neural Mechanism Mediates the Decision to Search in Stick Insects
A Leg-Local Neural Mechanism Mediates the Decision to Search in Stick Insects
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DOI：
10.1016/j.cub.2015.06.017
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发表时间：
2015-08-03
期刊：
影响因子：
9.2
通讯作者：
Bueschges, Ansgar
中科院分区：
文献类型：
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作者：
Berg, Eva M.;Hooper, Scott L.;Bueschges, Ansgar
在许多动物中，单个的腿既可以独立运作，如抓挠或搜索，也可以与其他腿协调使用，如行走或攀爬。虽然对行走的控制已经进行了广泛的研究，但对独立激活单个腿的行为选择的机制知之甚少。我们在竹节虫中研究了这一问题，在竹节虫中，如果没有找到落脚点，每条腿都可以独立地产生有节奏的搜索运动模式[1-4]。我们在这里展示了一个非尖峰中间神经元，14，控制着单个腿的搜索行为。一个14存在于胸椎三节的每半段[5,6]。诱导搜索的感官输入去极化。14 .活动对于发起和维持搜索行动是必要和充分的。当衬底接触时，14去极化不再引起搜索。因此，既整合了搜索诱导的感官输入，又被其他感官输入（基底接触）门控出来。因此，只有在行为合适的情况下才会进行搜索。去极化从未引起步进。这些数据表明，个体的、局部激活的神经元可以调节个体独立使用腿的行为选择。这种机制在昆虫的前腿上可能特别重要，前腿可以像脊椎动物的手臂和手一样独立运作。类似的局部命令机制，选择性地激活模式生成器，控制重复的功能单元，如腿或身体部分，可能存在于其他系统中。
In many animals, individual legs can either function independently, as in behaviors such as scratching or searching, or be used in coordinated patterns with other legs, as in walking or climbing. While the control of walking has been extensively investigated, the mechanisms mediating the behavioral choice to activate individual legs independently are poorly understood. We examined this issue in stick insects, in which each leg can independently produce a rhythmic searching motor pattern if it doesn't find a foothold [1-4]. We show here that one non-spiking interneuron, 14, controls searching behavior in individual legs. One 14 is present in each hemi-segment of the three thoracic ganglia [5, 6]. Search-inducing sensory input depolarizes 14. 14 activity was necessary and sufficient to initiate and maintain searching movements. When substrate contact was provided, 14 depolarization no longer induced searching. 14 therefore both integrates search-inducing sensory input and is gated out by other sensory input (substrate contact). Searching thus occurs only when it is behaviorally appropriate. 14 depolarization never elicited stepping. These data show that individual, locally activated neurons can mediate the behavioral choice to use individual legs independently. This mechanism may be particularly important in insects' front legs, which can function independently like vertebrate arms and hands [7]. Similar local command mechanisms that selectively activate the pattern generators controlling repeated functional units such as legs or body segments may be present in other systems.