Electrosensory processing in plankton capture by the paddlefish

白鲟捕获浮游生物的电传感处理

• 批准号: 0524869
• 负责人: Lon Wilkens
• 金额: $ 46.56万
• 依托单位: University of Missouri-Saint Louis
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-15 至 2010-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0524869&HistoricalAwards=false
• 关键词: Electrosensory; processing; plankton; capture; paddlefish

Electrosensory Processing in plankton capture by the paddlefishLon A. Wilkens, Principal InvestigatorThe electrosense is a specialized sensory modality of ancient fish and is best known in sharks that are able to detect the electrical fields of potential prey at close range and to use electromagnetic fields for navigation. Whereas these are macroscopic functions of the electrosense, the electrosensory system in the freshwater paddlefish has recently been shown to detect the weak electric fields of tiny plankton, the primary food source for the fish. The electroreceptors of this novel sensory system are present on an elongated rostrum, one-third the length of the fish, which constitutes an electrosensory organ the equivalent of an antenna. The exquisite sensitivity of this organ and its behavioral role in targeting planktonic prey makes it a useful model preparation in which to investigate the sensory processing of spatial features in the environment. Importantly, the brain contains a large, easily distinguishable region that is well suited for exploring the neural processing that underlies the feeding behavior. Dr. Wilkens' objective in this research proposal is to elucidate the neural circuitry and algorithms that enable the paddlefish to selectively target single plankton adrift in the turbid water column. Dr. Wilkens will study the electric signaling properties of sensory fibers coming from the receptors on the rostrum and the properties of neurons that the fibers contact in the hindbrain region, the dorsal octavolateralis nucleus (DON), which first processes the electrosensory information. Initial experiments will investigate the organization of sensory input into the DON. In sensory systems from other animals there is typically a topographic representation of peripheral receptive fields mapped out onto their target cells in the brain, such that adjacent brain cells correspond to nearby receptive fields. Early physiological recordings, however, have found no evidence for such topography in the paddlefish brain. To further investigate this unusual feature, Dr. Wilkens will use histological staining techniques that trace the nerve projections of the sensory fibers into the brain. This will provide direct neuroanatomical evidence for the organization of electrosensory processing in the brain.If it is confirmed that there is no topographical organization, other mechanisms for extracting spatial features must exist. Previous records of neural impulse activity from nerve cells in the DON show that their firing rates reflect the first derivative of an electrosensory stimulus waveform. Thus, brain cells respond preferentially to dynamical features of the stimulus signal, rather than to its magnitude. With the possibility that anatomical data will confirm the absence of spatial topography in the DON, Dr. Wilkens has developed a computer simulation model of a derivative filter whereby the information about the distance and velocity of an environmental signal could be encoded in the response neurons of the DON. The model will be tested by presenting electrical stimuli that move over the receptive fields in the rostrum, thus simulating the planktonic electric fields encountered by the fish during normal swimming. Recordings from these cells will be followed by the injection of nerve stains to trace their projections into higher midbrain regions. It is hypothesized that topographic representation will be established in the terminal projections of DON cells in the midbrain. Dr. Wilkens' descriptions of the electrosense in paddlefish has had broad implications for fisheries management of this threatened species, providing an explanation for why fish avoid metal structures (dams) in the rivers in addition to becoming an important model system for studying brain function. Dr. Wilkens will actively recruit underrepresented students from the St. Louis urban region to participate in this project.

白鲟捕捉浮游生物的电感觉过程。Wilkens，首席研究员电感觉是古代鱼类的一种特殊感觉方式，最为人所知的是鲨鱼，它们能够近距离探测潜在猎物的电场，并利用电磁场进行导航。 尽管这些都是电感觉的宏观功能，但淡水白鲟的电感觉系统最近被证明可以检测到微小浮游生物的微弱电场，浮游生物是鱼类的主要食物来源。 这种新感觉系统的电感受器存在于一个细长的喙上，长度是鱼的三分之一，它构成了一个相当于天线的电感觉器官。 这个器官的灵敏度和它的行为作用，在针对捕食性猎物，使其成为一个有用的模型准备，在其中调查的感觉处理的空间特征的环境。 重要的是，大脑包含一个大的，容易区分的区域，非常适合探索神经处理的基础上的喂养行为。 Wilkens博士在这项研究提案中的目标是阐明神经回路和算法，使白鲟能够选择性地瞄准漂浮在浑浊水柱中的单一浮游生物。Wilkens博士将研究来自喙上受体的感觉纤维的电信号特性，以及纤维在后脑区域接触的神经元的特性，背侧octavolateralis核（DON），它首先处理电感觉信息。 最初的实验将调查组织的感觉输入到DON。 在其他动物的感觉系统中，通常有一个周边感受野的地形图表示，映射到大脑中的目标细胞上，这样相邻的脑细胞就对应于附近的感受野。 然而，早期的生理记录没有发现白鲟大脑中存在这种地形的证据。 为了进一步研究这种不寻常的特征，Wilkens博士将使用组织学染色技术来追踪感觉纤维进入大脑的神经投射。 这将为大脑中的电感觉处理的组织提供直接的神经解剖学证据。如果证实没有地形组织，那么提取空间特征的其他机制就一定存在。 先前对DON神经细胞的神经冲动活动的记录表明，它们的放电率反映了电感觉刺激波形的一阶导数。因此，脑细胞优先响应刺激信号的动态特征，而不是其大小。 由于解剖学数据可能会证实DON中不存在空间拓扑结构，Wilkens博士开发了一种导数滤波器的计算机模拟模型，从而可以将有关环境信号的距离和速度的信息编码在DON的响应神经元中。 该模型将进行测试，提出的电刺激，在接受领域的吻部，从而模拟在正常的游泳过程中遇到的鱼的电刺激电场。 这些细胞的记录之后将注射神经染色剂，以追踪它们向更高的中脑区域的投射。 据推测，地形表示将建立在中脑DON细胞的终端投射。Wilkens博士对白鲟的电感觉的描述对这种受威胁物种的渔业管理产生了广泛的影响，除了成为研究大脑功能的重要模型系统之外，还解释了为什么鱼类会避开河流中的金属结构（水坝）。 威尔肯斯将积极招募来自圣路易斯市区代表性不足的学生参加这个项目。