Interaction between sex-steroids, electric signaling, and electrosensory processing in weakly electric fish

感觉器官向大脑提供源源不断的输入，大脑的主要任务之一是过滤输入的信息，并提取那些对做出行为决定很重要的方面。我研究的长期目标是了解大脑从输入流中提取行为相关信息的机制。脊椎动物大脑中感觉处理的一个特征是，来自感觉器官的输入被分成多个并行通道，这些通道专门处理传入信息的不同方面。由于这些通道必须在各种不同的环境和行为条件下工作（例如，昏暗的光与明亮的光，寻找食物与寻找配偶），它们的反应特性不断地调整以适应这些变化的条件。这些调节机制中的一些是内置于这些通道的单个神经细胞中的;一些是这些通道中的神经细胞群如何相互连接的结果;还有一些是由循环激素或神经调节物质的水平变化介导的，这些激素或神经调节物质在某些通道中局部起作用，而不是其他通道。此外，这三个层次的调节机制相互作用。在接下来的五年里，我将专注于类固醇激素在调节一组平行处理通道如何响应感官输入方面的作用。在脊椎动物中，类固醇激素被认为是控制生殖行为的核心，包括广告信号和攻击信号的产生和感知，但它们影响感官处理的机制仍然知之甚少。我将以弱电流鱼的电感觉系统为模型来说明这些机制。弱电鱼在其身体周围的水中产生电场，并感知其电场如何被附近物体或其他电鱼的电场干扰。因此，它们可以利用它们的电场进行物体（猎物）探测和通信。与其他感觉系统一样，电感觉系统将传入的信息分成多个并行通道，每个通道专门用于处理不同的刺激方面。这些通道中的每一个都可以根据不断变化的环境或行为条件来调整其处理特性。我将专门研究类固醇激素如何控制这些平行通道中的信息流。电感觉系统非常适合解决这个问题，因为首先，行为相关的刺激（不同性质的电场）可以很容易地量化，并在行为和神经生理学实验中重新创建;第二，我们可以建立在丰富的知识，神经解剖学，神经生理学反应特性，以及各种神经递质和神经调质的作用;第三，信息处理的多个并行通道为探索感觉反应特性是如何被控制的提供了一个奇妙的、实验上可及的基底。

Sense organs provide a constant stream of input to the brain, and it is one of the main tasks of the brain to filter the incoming information and extract those aspects that are important for making behavioural decisions. The long-term goal of my research is to understand the mechanisms used by the brain to extract behaviourally relevant information from this stream of input. A characteristic feature of sensory processing in the brains of vertebrates is that the input arriving from a sense organ is split into multiple parallel channels that are specialized to process different aspects of the incoming information. As these channels have to work under a variety of different environmental and behavioural conditions (e.g., dim light vs. bright light, searching for food vs. searching for a mate), their response properties are constantly adjusted to these changing conditions. Some of these adjustment mechanisms are built into the individual nerve cells of these channels; some are a consequence of how groups of nerve cells in these channels are interconnected; and some are mediated by changes in the levels of circulating hormones or of neuromodulatory substances that act locally in some channels, but not others. In addition, these three levels of adjustment mechanisms interact with each other. Over the next five years, I will focus on the role of steroid hormones in adjusting how a set of parallel processing channels responds to sensory input. Across vertebrates, steroid hormones are known to be central to the control of reproductive behaviour, including the production and perception of advertisement signals and aggressive signals, but the mechanisms by which they affect sensory processing are still poorly understood. I will address these mechanisms using the electrosensory system of weakly electric fish as a model. Weakly electric fish produce electric fields in the water surrounding their body and sense how their electric field is perturbed by the presence of nearby objects or by the electric fields of other electric fish. They can thus use their electric fields for object (prey) detection as well as communication. In the same way as other sensory systems, the electrosensory system splits the incoming information in multiple parallel channels, each of which is specialized for processing different stimulus aspects. And each of these channels can adjust its processing properties to changing environmental or behavioural conditions. I will study specifically how steroid hormones control information flow in these parallel channels. The electrosensory system is well suited to address this problem because, first, behaviourally relevant stimuli (electric fields of varying properties) can be easily quantified and recreated in behavioural and neurophysiological experiments; second, we can build on a wealth of knowledge on the neuroanatomy, neurophysiological response properties, and the role of various neurotransmitters and neuromodulators; and third, the multiple parallel channels of information processing offer a fantastic and experimentally accessible substrate for exploring how sensory response properties are controlled.