Investigating the neural code for single-word reading

描述(申请人提供)：成功的阅读需要大脑正确地识别印刷的单个单词。有人提出，单字阅读可以看作是视觉对象识别的一种特例，其双重目标是实现特定性和不变性。这一假设允许我们利用物体识别理论为单字阅读的神经基础提供假设，特别是视觉单词表征的性质，这种表征是如何由专业知识塑造的，以及如何受到注意效应的动态调节。该方案的具体目的是：a)确定自上而下的注意因素对单字阅读相关激活的影响；b)探索VWFA中神经元的选择性；c)确定词频如何影响VWFA中的神经表征。为了分离前馈和自上而下的注意成分，我们将使用掩蔽启动技术，该技术已被广泛用于检测单个单词的阅读。在这种范式中，受试者没有意识到启动，但许多行为研究表明启动效应。我们将把这项行为技术与功能磁共振结合起来。对掩蔽词的成像研究表明，神经元的激活主要集中在视觉区域，这表明受试者确实能感觉到刺激。然而，从这种大胆的回应中只能收集到这么多。最近，一种名为重复适应的技术被用于研究神经元的调谐。研究表明，重复刺激会导致激活减少，这被认为反映了专门处理该刺激的神经元群体。从适应中恢复相当于处理刺激的神经元数量的变化。强有力的初步数据表明，这种效应不仅允许我们更直接地探索神经元调谐，而且还提供了一个更好的机制模型，说明阅读任务中的表现是如何基于神经元调谐特性的。这个项目中提出的技术提供了一种创新的方法来检查枕颞叶皮质中单个单词阅读的神经关联。这项工作与公共健康的相关性在于它直接适用于阅读障碍的研究，其潜在的神经原因仍然知之甚少。例如，阅读困难的人在枕颞叶皮质经常表现出与阅读相关的激活改变。这项拟议的项目旨在使用先进的大脑成像和参数化行为技术来更直接地探测该区域激活的神经元基础，这将提供一个框架，在下一步可以应用于检查阅读障碍，最终导致更好地检测、诊断和治疗阅读障碍。

DESCRIPTION (provided by applicant): Successful reading requires the brain to correctly recognize printed individual words. It has been proposed that single-word reading can be viewed as a special case of visual object recognition with its dual goals of achieving specificity and invariance. This hypothesis allows us to leverage theories of object recognition to provide hypotheses for the neural bases of single-word reading, in particular the nature of the representation of visual words, how this representation is shaped by expertise, and is modulated dynamically by attentional effects. The specific aims of this proposal are to a) determine the impact of top-down attentional factors on single-word reading related activation, b) probe the selectivity of neurons in the VWFA and c) determine how word frequency affects the neural representation in the VWFA. To disentangle feed forward and top-down attentional components, we will use the masked priming technique, which has been widely utilized to examine single word reading. In this paradigm subjects are not consciously aware of the prime yet numerous behavioral studies show priming effects. We will combine this behavioral technique with functional MRI. Imaging studies of masked words show neuronal activation that is isolated mostly to visual areas indicating that subjects do perceive the stimuli. However, only so much can be gleaned from the BOLD response. Recently, a technique called repetition adaptation has been used to study neuronal tuning. Studies show that the repetition of a stimulus will result in reduced activation, which is thought to reflect a population of neurons specialized to process that stimulus. Recovery from adaptation corresponds to a change in the population of neurons processing the stimuli. Strong preliminary data suggest that this effect will not only allow us to probe neuronal tuning more directly, but also provide a better mechanistic model of how performance in reading tasks is based on neuronal tuning properties. The technique proposed in this project provides an innovative way to examine the neural correlates of single word reading in the occipitotemporal cortex. The relevance of this work for public health lies in its direct applicability to the study of reading disorders, whose underlying neural causes are still poorly understood. For instance, people with dyslexia often show altered reading-related activation in occipitotemporal cortex. The proposed project's aim to use advanced brain imaging and parameterized behavioral techniques to more directly probe the neuronal bases of activation in this area will provide a framework that in a next step can be applied to examine disordered reading, eventually leading to better detection, diagnosis, and treatment of reading disabilities.