Cortical spatiotemporal plasticity in humans

描述（由申请人提供）：本申请的总体目标是描述人类皮层可塑性的规则，通过基于MEG/EEG的成像分析，与听觉感知学习相关。破译大脑皮层可塑性和知觉学习的规则，对于制定旨在改善听觉感知的训练方案非常重要。听觉感知在很大一部分有学习障碍、阅读障碍、衰老或其他认知障碍的个体中受损。目前提出的概念理论框架是基于感知学习的逆向层次理论（RHT）。这一理论已经成功地统一了视觉感知学习的几个行为、解剖和生理发现。我们已经将RHT应用于听觉感知学习，并推导出一系列关于时空皮质可塑性和行为改善特征的可测试假设。RHT断言，学习是一个自上而下的引导过程，从听觉处理层次的高层区域开始，沿着这个层次向后推进到更早的输入水平，以便在层次的适当水平上增加成功表现所需的信号表示。在这里，我们在三个任务的背景下测试了RHT的几个预测，这些任务沿着听觉处理层次抽样了三个基本过程。这些任务是简单和复杂音调序列的调制率判别(R)和频率判别(F)，以评估时间、光谱和收敛光谱时间信息处理。第一个具体目标是检查由简短和广泛的训练方案引起的学习的比率和特异性。第二个具体目标是通过基于脑磁图/脑电图的成像分析学习诱导可塑性的特征。第三个具体目的是研究刺激变异性和心理物理任务条件对皮质可塑性和学习特征的影响。我们的方法是将心理声学研究与基于MEG/EEG数据的新颖时空源定位方法相结合来分析听觉感知学习。通过比较行为改善与皮层可塑性的特点，我们提出揭示与听觉知觉学习相关的皮层时空可塑性的一般规律。

DESCRIPTION (provided by applicant): The overall goal of this application is to delineate the rules of human cortical plasticity, assayed by MEG/EEG based imaging, associated with auditory perceptual learning. Deciphering the rules governing cortical plasticity and perceptual learning is important for the development of training protocols aimed at improving auditory perception, which is impaired in a large proportion of individuals with learning-disability, reading-impairment, aging or other cognitive impairments. The conceptual theoretical framework of the current proposal is based on the Reverse Hierarchy Theory of Perceptual Learning (RHT). This theory has been successful in unifying several behavioral, anatomical and physiological findings of visual perceptual learning. We have adapted RHT for auditory perceptual learning and derived a series of testable hypotheses for spatiotemporal cortical plasticity and for the characteristics of behavioral improvement. RHT asserts that learning is a top-down guided process, which begins at high-level areas of the auditory processing hierarchy and progresses backwards along this hierarchy to earlier input levels so as to increase signal representation at the appropriate level in the hierarchy that is required for successful performance. Here, we test several predictions from RHT in the context of three tasks that sample three fundamental processes along the auditory processing hierarchy. These tasks are modulation-rate discrimination (R) and frequency discrimination (F) of simple and complex tone-trains to assess temporal, spectral and convergent spectrotemporal information processing. The first specific aim is to examine the rate and specificity of learning induced by brief and by extensive training protocols. The second specific aim is to examine characteristics of learning-induced plasticity, assayed by MEG/EEG based imaging. The third specific aim is to examine the effects of stimulus variability and psychophysical task conditions on cortical plasticity and learning characteristics. Our approach is to combine psychoacoustic studies to assay auditory perceptual learning with novel spatiotemporal source localization methods from MEG/EEG data. By comparing characteristics of behavioral improvements with cortical plasticity we propose to unravel general rules of cortical spatiotemporal plasticity associated with auditory perceptual learning.