Context-dependent neural coding

来自神经元系统的输出通过作用于不同时间尺度的各种机制来适应刺激的变化。许多系统表现出一种快速的适应形式，通过这种适应，刺激相对于它们所呈现的上下文被编码。这种形式的上下文调制编码在感觉和更高级的系统中无处不在，并且可以支持神经系统有效地编码复杂自然刺激的能力。实验表明，这种形式的增益控制既发生在神经系统中，也发生在皮层中的单个神经元中。在较长的时间尺度上，神经系统在长时间暴露于恒定刺激后表现出活动减少。有人提出，这种行为是内在的神经元动力学，可能有助于有效的编码缓慢变化的刺激包络的反映。这个项目将进一步发展的假设，这些缓慢的动态可能反映了系统的不断变化的输入统计特性的估计。这些自适应行为的机制将与理论分析和现实的神经元模型的模拟相结合。该项目的目标是阐明有效编码时变信号的基本神经机制的数学基础，并揭示采样和表示复杂自然环境的最佳策略。这项工作研究了适用于多种感觉和更高层次大脑系统的神经编码机制，并将有助于开发一种可以跨这些领域翻译的语言和方法。这项工作的跨学科性质将为从数学和物理学到生物学的本科生和研究生提供培训机会。该项目包括为高级高中学生开设暑期课程。

The outputs from neuronal systems adapt following a change in a stimulus, through a variety of mechanisms acting on different timescales. Many systems show a rapid form of adaptation through which stimuli are encoded relative to the context within which they were presented. This form of context-modulated coding is ubiquitous through sensory and higher-level systems, and may support the ability of the nervous system to efficiently encode complex natural stimuli. Experiments have shown that this form of gain control occurs both in neural systems and in single neurons in the cortex. On longer timescales, neural systems show a decrease of activity after long exposure to a constant stimulus. It is proposed that this behavior is a reflection of intrinsic neuronal dynamics that may contribute to the efficient coding of the slowly-varying stimulus envelope. This project will further develop the hypothesis that these slow dynamics may reflect the system's ongoing estimate of the changing statistical characteristics of the input. The mechanisms for these adaptive behaviors will be pursued with a combination of theoretical analysis and simulation of realistic neuronal models. The project's goal is to elucidate the mathematical basis of fundamental neural mechanisms for the efficient encoding of time-varying signals and reveal optimal strategies for sampling and representing complex natural environments. This work examines neural coding mechanisms that apply to multiple sensory and higher brain systems and will help to develop a language and methodology that can translate across these areas. The interdisciplinary nature of the work will provide training opportunities for undergraduate and graduate students crossing over from mathematics and physics to biology. The project includes the development of a summer course for advanced high school students.