RUI: Ionic Conductances Underlying Serotonergic Modulation of Rhythmic Motor Behavior

詹姆士·D·安施塔特-研究节律性运动的血清素能调节下的SUMMARYIONIC行为神经系统最重要的功能之一是控制运动。走路、游泳和飞行都是有节奏的运动行为的例子，这些行为包括相对固定的肌肉收缩模式。为了生存，动物还必须能够改变它的运动和其他行为，以满足不断变化的环境的要求。例如，作为对不断增加的饥饿的反应，动物可能会增加给定的感官刺激，如检测到潜在猎物，将导致激活运动行为，使动物向猎物移动的可能性。因此，神经生物学的一个重要目标是了解作为运动行为基础的神经回路是如何随着时间的推移而改变的。在无脊椎动物和脊椎动物身上实现电路功能改变的一种方式是使用称为神经调节剂的化学物质改变神经元的电和突触属性。研究最深入的运动行为神经调节剂之一是一种叫做5-羟色胺的化学物质。在这个项目中，将研究5-羟色胺对药用水蚤运动神经元控制游泳行为的影响。由于相对简单，水蚤是少数几种能够追踪从感官输入到节奏产生回路，然后再到产生实际动作的肌肉的连续路径的生物之一。饥饿的水蚤在其神经元周围的血液中有更高水平的5-羟色胺，因此更有可能游泳。此外，5-羟色胺影响游泳行为通路中几种类型神经元的电特性。然而，目前还不清楚5-羟色胺是如何影响这些神经元导致游泳概率增加的。这一信息将通过在受控条件下直接测量接触5-羟色胺前后水蚤游泳运动神经元中的离子电流来获得。在确定了那些被5-羟色胺修饰的离子电流之后，这种神经调节剂引起的具体变化将被识别出来。将结果数据与各种无脊椎动物和脊椎动物的运动行为调节研究进行比较，将有助于阐明所有动物(包括人类)控制运动行为的一般原理。

JAMES D. ANGSTADT - PROJECT SUMMARYIonic Conductances Underlying Serotonergic Modulation of Rhythmic MotorBehavior One of the most important functions of the nervous system is to control movement. Walking, swimming and flying are examples of rhythmic motor behaviors that consist of a relatively stereotyped pattern of muscle contractions. To survive, an animal must also be able to modify its motor and other behaviors to meet the demands of a changing environment. In response to increasing hunger, for example, an animal may increase the probability that a given sensory stimulus, such as detection of potential prey, will lead to activation of motor behaviors that move the animal toward the prey. Thus, an important goal in neurobiology is to understand how the neural circuits underlying motor behavior are modified over time. One way that changes in circuit function are achieved in both invertebrate and vertebrate animals is to alter the electrical and synaptic properties of neurons with chemicals called neuromodulators. One of the most well studied neuromodulators of motor behavior is a chemical called serotonin. In this project, the effects of serotonin on motor neurons controlling swimming behavior in the medicinal leech will be examined. Because of its relative simplicity, the leech is one of only a handful of organisms in which it has been possible to trace a continuous pathway from sensory input to the rhythm-generating circuit and then out to the muscles that generate the actual movements. Hungry leeches have higher levels of serotonin in the blood surrounding their neurons and, as a result, are more likely to swim. Moreover, serotonin affects the electrical properties of several types of neurons found in the swim behavior pathway. However, it is not yet understood exactly how serotonin affects these neurons to cause the increased probability of swimming. This information will be obtained by measuring directly, under controlled conditions, the ionic currents in swim motor neurons of the leech before and after exposure to serotonin. After identifying those ionic currents modified by serotonin, the specific changes induced by this neuromodulator will be identified. Comparison of the resulting data with research on modulation of motor behaviors in a variety of invertebrate and vertebrate species will contribute to the elucidation of general principles underlying the control of motor behavior in all animals, including humans.