The Organization of Semantic Memory

描述（由申请人提供）：本研究提案的广泛目标是更好地了解如何在未受损和脑损伤的个体中访问和组织语义信息。具体来说，它将评估以下假设：（1）对象的概念分布在语义特征上，共享特征的概念具有重叠的表示，以及（2）这些特征在我们感知和/或与对象交互时调用的神经基质中表示。将使用三种互补的方法对这些索赔进行调查。第一个是眼动跟踪范式，这将有助于建立未受损的个人自动激活概念的各种语义属性和这些属性被激活的时间过程的程度。第二个是一个功能磁共振成像适应范式，将显示是否感觉运动皮层对应的概念的属性自动激活时，概念被检索，以及不同的，但相关的概念的神经表征是否重叠。第三种方法跟踪难以获得语义知识的脑损伤患者的眼球运动，并使用结果创建基于体素的病变症状图，将语义记忆缺陷与脑损伤的特定区域联系起来。深入了解这些患者的缺陷可能会改善诊断和/或治疗。总之，这些调查将导致更好地理解语义信息是如何组织的，访问和表示在正常的主题，以及语义信息如何退化与各种脑损伤。

DESCRIPTION (provided by applicant): The broad goal of this research proposal is to better understand how semantic information is accessed and organized in unimpaired and brain-damaged individuals. Specifically it will evaluate the hypotheses that: (1) the concept of an object is distributed over semantic features, with concepts that share features having overlapping representations, and (2) these features are represented in the neural substrates that are invoked when we perceive and/or interact with the object. These claims will be investigated using three complementary methodologies. The first is an eye tracking paradigm that will help to establish the extent to which unimpaired individuals automatically activate a concept's various semantic attributes and the time course over which these attributes are activated. The second is an fMRI adaptation paradigm that will show both whether sensorimotor cortices corresponding to a concept's attributes are automatically activated when the concept is retrieved, and whether the neural representations of different but related concepts overlap. And the third methodology tracks the eye movements of brain-damaged patients who have difficulty accessing semantic knowledge, and uses the results to create voxel-based lesion-symptom maps linking semantic memory deficits to specific regions of brain damage. Gaining insight into these patients' deficits could lead to improved diagnoses and/or treatments. Together, these investigations will lead to a better understanding of how semantic information is organized, accessed and represented in normal subjects, and how semantic information degrades with various kinds of brain damage.