Wood D E
Georgia State University, Department of Biology, Atlanta 30302-4010, USA.
J Comp Physiol A. 1995 Sep;177(3):335-49. doi: 10.1007/BF00192422.
The blue crab Callinectes sapidus, provides an opportunity to study neuromodulation of three variations of rhythmic behavior produced by the same appendages. These behaviors are sideways swimming, backward swimming and courtship display (CD). Each behavior has a different context, and despite similarities among them, each is quantifiably distinguishable. CD behavior occurs in males, is stimulated naturally by pheromone, and elements of the behavior are evoked by proctolin and dopamine. Sideways and backward swimming do not share these characteristics. Bath-applied proctolin, combined with either electrical or pheromonal stimulation, was used to search for interneurons influencing motor outflows from the fifth legs. Interneurons were found which, when stimulated electrically, initiated rhythmic behavior. At least one of these neurons responded to pheromonal stimulation. Application of proctolin combined with stimulation of descending 'trigger' cells resulted in changes from a backward swimming motor pattern toward a CD pattern. Dopamine applied with proctolin lowered the concentration threshold for proctolin-evoked changes in motor outflows. Octopamine co-applied with proctolin extinguished the proctolin effect unless dopamine was co-applied. Combinations of modulators appear to play critical roles in shaping patterns of rhythmic motor activity of the fifth legs.
青蟹（Callinectes sapidus）为研究同一附肢产生的三种节律性行为变化的神经调节提供了契机。这些行为包括侧向游泳、向后游泳和求偶展示（CD）。每种行为都有不同的背景，尽管它们之间存在相似之处，但每种行为在数量上都是可区分的。求偶展示行为发生在雄性青蟹中，由信息素自然刺激引发，并且该行为的一些成分可由促胃液素和多巴胺诱发。侧向游泳和向后游泳则不具备这些特征。通过浸浴施用促胃液素，并结合电刺激或信息素刺激，来寻找影响第五对步足运动输出的中间神经元。发现了一些中间神经元，当对其进行电刺激时，会引发节律性行为。这些神经元中至少有一个对信息素刺激有反应。施用促胃液素并结合刺激下行“触发”细胞，会导致运动模式从向后游泳转变为求偶展示模式。将多巴胺与促胃液素一起施用可降低促胃液素诱发运动输出变化的浓度阈值。除非同时施用多巴胺，否则将章鱼胺与促胃液素共同施用会消除促胃液素的作用。调节剂的组合似乎在塑造第五对步足的节律性运动活动模式中起着关键作用。
