Neural development of lexical processing

描述(由申请者提供)：本项目的目标是使用功能磁共振成像(FMRI)检查正常儿童(7-15岁)在词汇处理的神经底物上的发育和个体差异。我们建议通过词汇任务来考察这些差异，这些任务旨在利用通道内加工(听觉押韵和视觉拼写任务)、跨通道加工过程中正字法和音位之间的转换(听觉拼写和视觉押韵任务)和情态词理解(听觉和视觉意义任务)。这项提议有三个具体目标。首先，我们将使用横截面和纵向相结合的设计，以便在相对较短的时间内测量较大年龄范围内词汇加工的发展变化。我们预计，发育将导致与输入方式一致的单峰区的激活增加，而在后部异交感区域的激活减少。其次，我们将研究大脑激活与个体技能差异之间的相关性是否取决于发展水平。我们预计，对于年龄较大的儿童，行为将与词汇任务所需的认知成分相关，但对于年龄较小的儿童，行为与后部异峰激活的相关性较弱。第三，我们将考察听觉和视觉输入方式之间以及拼写、押韵和意义任务之间激活重叠的发展差异。我们预计，年龄较小的儿童会比年龄较大的儿童在道德和任务之间表现出更多的激活重叠。这些特定的目标还包括参数操作和每个词汇任务的简单与复杂基线，这样我们就可以更清楚地将任务中激活的差异与词汇加工的发展或技能差异联系起来。由于很少有功能磁共振研究直接考察词汇加工的发展或个体差异，这个针对正常人群的项目将对未来儿童阅读和语言障碍的神经基础研究产生影响。

DESCRIPTION (provided by applicant): The goal of this project is to examine developmental and individual differences in the neural substrate for lexical processing in normal children (7-15 year olds) using fMRI (functional magnetic resonance imaging). We propose to examine these differences with lexical tasks designed to tap into intra-modal processing (auditory rhyming and visual spelling tasks), conversion between orthography and phonology during crossmodal processing (auditory spelling and visual rhyming tasks) and modal word comprehension (auditory and visual meaning tasks). This proposal has three specific aims. First, we will use a combination of a cross-sectional and longitudinal design in order to measure developmental changes in lexical processing across a wide age range in a relatively short amount of time. We expect that development will produce increased activation in unimodal areas consistent with the modality of input and decreased activation in posterior heteromodal areas. Second, we will examine whether the correlation between brain activation and individual differences in skill depends on developmental level. We expect that behavior will correlate with the cognitive components required by the lexical task for older children, but will weakly correlate with posterior heteromodal activation for younger children. Third, we will examine developmental differences in the overlap in activation between auditory and visual modalities of input and between the spelling, rhyming and meaning tasks. We expect that younger children will show more overlap in activation than older children between moralities and between tasks. These specific aims also incorporate parametric manipulations and a simple versus complex baseline for each lexical task, so that we can more clearly relate differences in activation during tasks to either developmental or skill differences in lexical processing. Because few fMRI studies have directly examined developmental or individual differences in lexical processing, this project on a normative population will have implications for future studies on the neural basis of reading and language impairments in children.