The Mechanisms of Perceptual Learning

描述（由申请人提供）：感知学习（PL）被定义为作为训练或暴露于视觉特征的结果的视觉特征的性能提高，并且被认为是感觉/感知处理中可塑性的表现。虽然我们正在进行的项目（R 01 EY 015980）已经揭示了外部因素如何门PL，目前的建议将解决一个更基本但尚未回答的问题;神经机制如何改变与PL的相关性？已经发现，几个因素从根本上影响PL的机制。首先，PL是作为检测任务和辨别任务的训练（任务相关学习）或暴露于随时间呈现的任务无关特征（任务无关学习）的结果而形成的。不同的训练方法对PL机制的影响是不同的。第二，PL的神经处理似乎随着学习的进行而发生很大变化。第三，外部反馈的主题，他们的表现，一项任务可以促进PL或在某些情况下是必要的PL。然而，这3个因素如何影响PL的神经机制尚不清楚。我们将通过系统地检查在大脑视觉处理的多个区域中获得的训练特征的调谐功能的变化来解决这个问题。为此，我们将测量被视为反映神经活动的血氧水平依赖（BOLD）信号。具体而言，BOLD响应调谐功能的变化将在与PL相关的视觉处理的多个领域中进行测量。我们将首先研究如何通过不同的训练方法，如检测任务的训练，辨别任务的训练和暴露于任务无关的功能，BOLD活动的变化发生，并解决有关如何从不同的训练方法导致的神经变化是相互关联的问题。其次，我们将研究BOLD活动的变化是如何发生在学习的时间过程中。请注意，BOLD响应调谐函数变化可以表征为某些特征值的响应增加和/或其他值的响应减少。我们将研究如何相对BOLD响应增加和减少发生在调谐功能在学习的时间过程中，也测试是否BOLD信号的增加和减少源于相同的机制。第三，我们将研究外部反馈是否以及如何影响BOLD反应调节功能的变化，反映在视觉处理的多个领域。如果反馈影响BOLD响应调谐功能，我们将进一步研究它是否有利于响应增加，响应减少，或两者兼而有之，在响应调谐功能。总体而言，虽然3个基本因素引起的神经变化似乎差异很大，但当前提案的3个目标的系统研究可以澄清，理论上是否可以将这些变化视为导致反应增加的兴奋性输入和导致反应减少的抑制性信号在PL的时间过程中的组合的结果。公共卫生相关性拟议的研究具有潜在的临床应用，有助于科学知识，导致改善诊断和康复治疗，大脑疾病和病变，特别是那些与感觉功能。

DESCRIPTION (provided by applicant): Perceptual learning (PL) is defined as performance increase of a visual feature as a result of training or exposure to the feature and is regarded as a manifestation of plasticity in sensory/perceptual processing. While our on-going project (R01EY015980) has revealed how external factors gate PL, the current proposal will address a more fundamental but unanswered question; how do neural mechanisms change in correlation with PL? It has been found that several factors fundamentally influence the mechanism of PL. First, PL is formed as a result of training of a detection task and a discrimination task (task-relevant learning) or exposure to a task- irrelevant feature presented over time (task-irrelevant learning). Different training methods could influence the mechanisms of PL in different ways. Second, the neural processing of PL seems to greatly change as learning proceeds. Third, external feedback to subjects as to their performance of a task can facilitate PL or in some cases is necessary for PL. Nevertheless, it has yet to be clarified how these 3 factors influence the neural mechanisms of PL. We will address this question by systematically examining changes of tuning functions of a trained feature that are obtained in multiple areas of visual processing in the brain. For this purpose, we will measure blood oxygen level dependent (BOLD) signals that are regarded as reflecting neural activity. Specifically, BOLD response tuning function changes will be measured in multiple areas of visual processing in correlation with PL. We will first examine how BOLD activity changes occur by the different training methods such as training of a detection task, training of a discrimination task and exposure to a task-irrelevant feature and address the question concerning how neural changes resulting from different training methods are related to each other. Second, we will examine how BOLD activity changes occur during the time course of learning. Note that BOLD response tuning function changes can be characterized as response increases for some feature values and/or decreases for other values. We will examine how relative BOLD response increases and decreases occur in tuning functions during the time course of learning and also test whether BOLD signal increases and decreases originate from the same mechanism. Third, we will examine whether and how external feedback influences BOLD response tuning function changes reflected in multiple areas of visual processing. If feedback influences BOLD response tuning functions, we will further investigate whether it facilitates response increase only, response decrease only, or both, in response tuning functions. Overall, while the neural changes by the 3 fundamental factors appear to be highly different, the systematic investigation in 3 aims of the current proposal may clarify whether it is theoretically possible to view these changes as a result of combinations of excitatory inputs that cause response increases and inhibitory signals that cause response decreases over the time course of PL. PUBLIC HEALTH RELEVANCE The proposed research has potential for clinical applications by contributing to scientific knowledge leading to improved diagnosis of, and rehabilitative therapies for, brain disorders and lesions, in particular those related to sensory function.