Neurocomputational models of sequential discrimination

描述(由申请者提供)：这项申请旨在深入了解短期记忆被保持的机制，并与感觉相互作用，以产生决定。将对执行体感顺序辨别任务的猴子的数据进行分析和计算建模。这项任务既包括短期记忆部分(受试者必须记住每次试验中的第一个刺激)，也包括决定部分(每次试验中的第二个刺激必须与第一个进行比较，并且必须根据比较做出决定)。 具体目标有三个：(1)建立序列辨别任务的计算神经模型。利用这些模型，我们将探索生物物理机制，通过这些机制，第一个刺激可能被加载到短期记忆中；保存在短期记忆中；并与第二个刺激相结合，从而根据两个刺激的比较形成决策。我们将探索如何在一个基于生物物理学的神经网络中组合和理解所有三个任务组成部分(加载、记忆和比较/决策)。(2)基于连续变量的短期记忆被保持在动态逼近连续吸引子的网络中的思想，我们提出了神经元之间的噪声相关性模型。这个模型从根本上协调了第一刺激记忆的神经生理学表征的精确度与猴子受试者的行为精确度，正如从心理生理上推断的那样。我们将分析同时记录的PFC神经元之间的相关性，并寻找支持或反对这一噪声模型的证据。(3)假设关于第一和第二刺激之间的比较是在PFC和/或第二躯体感觉皮质(S2)做出的，并且PFC在时间上领先于S2，这一假设将通过分析任务期间从这些皮质区域记录的数据来检验。 我们的长期目标是了解记忆背景如何影响基于传入感觉数据的决策；也就是说，我们寻求对背景相关决策的神经生理学基础的理解。从长远来看，这项研究可能会对人们对心理健康的理解产生重大影响。

DESCRIPTION (provided by applicant): This application seeks to gain insight into the mechanisms by which short-term memories are held and interact with sensations in order to produce decisions. Data from monkeys performing a somatosensory sequential discrimination task will be analyzed and modeled computationally. This task involves both a short-term memory component (subjects must remember the first stimulus in each trial) and a decision component (the second stimulus in each trial must be compared to the first, and a decision must be made based on that comparison). Three specific aims will be addressed: (1) We will build computational neural models of the sequential discrimination task. Using these models, we will explore biophysical mechanisms by which the first stimulus may be loaded into short-term memory; preserved in short-term memory; and combined with the second stimulus, so as to form a decision based on the comparison of the two stimuli. We will explore how all three task components (loading, memory, and comparison/decision-making) may be combined and understood in a single biophysically-based neural network. (2) Based on the idea that the short-term memory of continuous variables is held in networks with dynamics that approximate a continuous attractor, we propose a model of noise correlations between neurons. This model fundamentally reconciles the precision of the neurophysiological representation of the memory of the first stimulus with the behavioral precision of the monkey subjects, as inferred psychophysically. We will analyze correlations between simultaneously recorded PFC neurons and seek evidence for, or against, this noise model. (3) The hypothesis that a decision regarding the comparison between the first and second stimulus is made in the PFC and/or the secondary somatosensory cortex (S2), with the PFC leading S2 in time, will be tested by analyzing data recorded from these cortical areas during the task. Our long-term goal is to understand how memory context can affect decisions based on incoming sensory data; that is, we seek an understanding of the neurophysiological basis of context-dependent decisions. In the long term, this research could potentially have significant impact on the understanding of mental health.