Context-dependent neural coding

神经系统的输出随着刺激的变化而变化，通过作用于不同时间尺度的各种机制进行调整。许多系统表现出一种快速的适应形式，通过这种形式，刺激相对于呈现它们的上下文进行编码。这种形式的上下文调制编码通过感觉和更高级别的系统普遍存在，并可能支持神经系统有效地编码复杂的自然刺激的能力。实验表明，这种形式的增益控制既发生在神经系统中，也发生在大脑皮层的单个神经元中。在较长的时间尺度上，神经系统在长期暴露于持续刺激后表现出活动减少。有人提出，这种行为是内在神经元动力学的反映，这可能有助于对缓慢变化的刺激包络进行有效编码。这个项目将进一步发展这样的假设，即这些缓慢的动态可能反映系统对不断变化的输入统计特征的持续估计。这些适应行为的机制将通过理论分析和现实神经元模型的模拟相结合来探索。该项目的目标是阐明对时变信号进行有效编码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个感觉和高级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区域进行翻译的语言和方法。这项工作的跨学科性质将为从数学、物理到生物的本科生和研究生提供培训机会。该项目包括为高中生开发暑期课程。

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.