Dynamics of electric sensing

生物电场在自然界中无处不在；它们是我们动作、心跳和思想的基础。在大脑中，这些电场来自控制行为的神经元网络的时变活动，并反映在脑电图（EEG）中，我们可以通过放置在头皮上的感应电极记录脑电图。虽然脑电图可以告诉我们大脑的整体状态，但我们对如何从这个全局信号中确定局部网络的功能知之甚少。想象一下，听到远处体育场里的人群不断发出吼声，你知道有什么事情发生了，但你不知道是什么，也不知道为什么，也不知道体育场里是谁在欢呼。我们想知道像脑电图这样的信号背后的“是什么”、“为什么”和“谁”。事实证明，大自然已经解决了一个类似的问题：电鱼利用电场的时空变化来描述它们的环境。******弱电鱼会产生振荡电场，受到周围物体的干扰。这些扰动被皮肤上特殊的电感受器编码，使鱼能够在黑暗中导航、捕捉猎物和交流。这涉及到一个重大挑战：电场扰动是微不足道的（我们完全无法察觉），并且经常被高水平的背景噪声污染，包括其他鱼类的电信号。***鱼用两种策略克服了这个挑战。首先，电鱼动态地前后游动，利用运动提取最大信息。其次，它们振荡电场的时钟式计时比任何其他生物时钟都精确得多，甚至可以检测到最小的调制。我的建议集中在两个基本问题的背景下这些策略：******(1)运动如何影响感官信息的获取？***(2)脑网络如何控制定时精度？******我们的方法是多学科的，将行为研究与电生理学和计算建模相结合。我们使用虚拟现实系统来探测电感觉知觉，同时通过主动运动控制鱼可获得的信息。通过单个神经元的记录和特定的网络操作，我们发现了能够实现高度精确的神经活动的大脑机制。这些研究是由电场动力学和神经网络的详细计算模型提供的。这个多学科的培训基地是各级学生的理想选择，为他们在生物技术和高科技领域以及政府实验室和学术界的广泛职业做好准备。******了解这种精致的电感不仅将为了解电鱼的奇异世界提供一扇窗户，而且还将增加我们对一般感觉的理解。反过来，这将影响神经科学的各个领域，使我们能够更好地解释我们自己大脑中的电场。* * * * *

***Bioelectric fields are ubiquitous in nature; they underlie our movements, our heart beat, and our thoughts. In the brain, these electric fields arise from the time-varying activity of the neuronal networks that control behaviour, and are reflected in the electroencephalogram (EEG) that we can record with sensing electrodes placed on our scalp. While the EEG can tell us about overall brain state, we know relatively little about how to determine the function of local networks from this global signal. Imagine hearing the repeated roars of a crowd in a distant stadium you know something is happening, but you don't know what or why, or who in the stadium is actually cheering. We would like to know the “what”, “why” and “who” underlying signals like the EEG. It turns out that nature has already solved a similar problem: electric fish use the spatiotemporal changes in electric fields to characterize their environment. ******Weakly electric fish generate an oscillating electric field that is perturbed by surrounding objects. These perturbations are encoded by specialized electroreceptors on the skin, allowing the fish to navigate, capture prey and communicate in the dark. This involves a significant challenge: electric field perturbations are miniscule (entirely undetectable to us) and often contaminated with high levels of background noise, including the electric signals of other fish. ***The fish overcomes this challenge using two strategies. First, electric fish dynamically swim backwards and forwards, using motion to extract maximal information. Second, the clock-like timing of their oscillating electric field is much more precise than any other biological clock, allowing even the smallest modulations to be detected. My proposal focuses on these strategies in the context of two fundamental questions: ******(1) How does motion influence the acquisition of sensory information?***(2) How do brain networks control timing precision? ******Our approach is multi-disciplinary, combining behavioural studies with electrophysiology and computational modeling. We use a virtual reality system to probe electrosensory perception while controlling the information available to the fish through active movements. And using single neuron recordings and specific network manipulations, we discover the brain mechanisms that enable highly precise neural activity. These studies are informed by detailed computational models of electric field dynamics and neural networks. This multidisciplinary training ground is ideal for students at all levels, preparing them for a wide range of careers in biotechnology and high-technology, as well as in government labs and academia. ******Understanding this exquisite electric sense will not only provide a window into the exotic world of electric fish, but will also increase our understanding of sensing in general. In turn, this will impact diverse areas in neuroscience and enable us to better-interpret the electric fields in our own brains. *****