Neural Mechanisms of Task Specific Changes in Sensorimotor Processing

当动物在它们的环境中移动时，它们需要产生一种既适合推进又适合引导动物走向通过视觉、化学感觉、听觉或触觉线索识别的目标的运动输出。在这项任务的过程中，运动活动被修改以允许在运动路径中产生曲率或超越或爬过障碍物。产生运动输出的神经网络位于运动器官水平的节段中枢神经系统中：例如，在昆虫中，这些网络位于胸神经索中。为了产生运动行为，这些网络受到来自大脑高级区域的持续下行控制。下行信号不仅维持运动活动，还允许对实际运动输出进行持续修改和调整，以满足上述行为需求。改变行走方向是接近目标时一种简单而又必要的动作。不对称的运动学腿的运动在任何一边允许这样的机动。在产生目标定向运动行为的过程中，来自大脑高阶中心的信号是如何影响节段网络的，以及运动网络的哪些组成神经元受到影响，目前尚不清楚。该项目旨在缩小竹节虫的知识差距，竹节虫是一种动物，在单腿行走的产生中，关于节段感觉反馈的作用的相当详细的信息是可用的。先前对这种动物的研究提出了一种假设，即在节段网络中处理感觉反馈的改变通常会导致这种改变。该项目应回答以下问题：1。在对来自地面接触、运动和负荷传感器的感觉反馈的影响和处理中发生了什么变化，这取决于单腿必须服务的行为任务，即在弯曲行走中作为外侧腿或内侧腿？2. 为了控制曲线行走动物两侧的运动活动，运动信号的处理是如何被修改的？3. 为了在生成曲线行走的运动输出时允许上述修改，分段前运动网络中的哪些组成神经元受到影响？

When animals move through their environment, they need to generate a motor output suitable for both propulsion as well as directing the animal towards goals that have been identified by means of visual, chemosensory, auditory or tactile cues. In the course of this task locomotor activity is modified to allow for the generation of curvatures in the locomotor path or to surpass or climb over obstacles. The neural networks generating the motor output for locomotion are localized in the segmented central nervous systems at the level of the locomotor organs: in insects, for example, these networks reside in the thoracic nerve cord. To generate locomotor behavior, these networks are under continuous descending control from higher brain regions. The descending signals not only maintain motor activity, but also allow for continuous modification and adjustment of the actual locomotor output to serve the behavioral needs described above. A change in walking direction is a simple and often necessary maneuver for approaching a goal. Asymmetric kinematics of leg movements on either side allow for such maneuver. At present it is not clear, how signals from higher order centers in the brain influence the segmental networks and which component neurons of the locomotor networks are affected in the course of generating goal directed locomotor behavior. This project aims to close this gap in knowledge working on the stick insect, an animal for which considerable detailed information on the role of segmental sensory feedback in the generation of single leg stepping is available. Previous studies in this animal gave rise to the hypothesis that modifications in the processing of sensory feedback within the segmental networks might in general contribute to such modifications. The project shall answer the following questions: 1. What modifications occur in the influence and processing of sensory feedback from ground contact, movement and load sensors in dependence of the behavioral task a single leg has to serve, i.e. as an outside or an inside leg in curve walking? 2. How is processing of movement signals underlying reinforcement of movement modified in order to serve the control of motor activity on either side of a curve walking animal? 3. Which component neurons in the segmental premotor network are influenced in order to allow for the above described modifications in the generation of a motor output for curve walking?