The Organization of Semantic Memory

描述（由申请人提供）：本研究计划的总体目标是更好地理解未受损和脑损伤个体如何获取和组织语义信息。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征，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。这些主张将使用三种互补的方法进行调查。第一个是眼动追踪范式，它将有助于确定未受损个体自动激活一个概念的各种语义属性的程度，以及这些属性被激活的时间过程。第二个是fMRI适应范式，它将显示当概念被检索时，与概念属性相对应的感觉运动皮层是否自动激活，以及不同但相关的概念的神经表征是否重叠。第三种方法是追踪难以获取语义知识的脑损伤患者的眼球运动，并利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，这些研究将有助于更好地理解语义信息在正常受试者中是如何组织、获取和表示的，以及语义信息是如何随着各种脑损伤而退化的。

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.