The nature of parietal involvement in visual short-term memory

描述（由申请人提供）：本修订提案的目的是进一步详细说明后顶叶皮层（PPC）在视觉短期记忆（VSTM）中的作用。一些功能性磁共振成像（fMRI）研究观察到双边PPC激活在不同的VSTM任务。相比之下，PPC损伤与VSTM表现的普遍缺陷无关。已知右侧PPC损伤会损害空间注意力，而左侧PPC损伤会损害数字大小的处理。功能磁共振成像和病人的数据之间的冲突提出了几种可能性：VSTM赤字PPC患者没有仔细评估，或神经成像激活是副现象VSTM任务的表现。在初步研究中，我发现，单侧右PPC患者表现出一般的障碍，在VSTM的对象，空间和对象空间VSTM的颜色，新颖的形状和工具刺激类别。左侧PPC患者未表现出一般VSTM缺陷，在VSTM任务中表现正常。双侧PPC患者的视觉失认症（无法看到一个以上的事情在同一时间）也是全球性的损害。双侧PPC也表现出对实验范式的敏感性，并且在旧/新VSTM识别中的表现比可比回忆任务更差。本研究的目的是探讨PPC参与VSTM的参数。解决未解决的问题：VSTM损伤的机制（编码、维持、容量、提取）、再认范式（旧/新再认与2种强迫选择）是否影响双侧PPC再认成绩、左侧PPC激活是否与加工量有关。为了实现这一目标，我建议研究VSTM使用免费的方法：单侧和双侧顶叶患者的神经心理学研究，以及功能性磁共振成像（fMRI）与正常人。公共卫生相关性：这组研究与顶叶卒中患者的康复特别相关。在美国，中风每年影响大约70万人，是第三大死亡原因，并且是严重、长期残疾的主要原因。顶叶中风相对常见，对视觉和行动的行为后果是毁灭性的。在拟议的研究中，顶叶患者的VSTM损伤进行了评估。VSTM的缺陷对认知功能有直接的现实影响。这些数据可以提供负担得起的评估措施，并帮助指导康复战略。

DESCRIPTION (provided by applicant): The aim of this revised proposal is to further detail the role of the posterior parietal cortex (PPC) in visual short-term memory (VSTM). A number of functional magnetic resonance imaging (fMRI) studies observe bilateral PPC activations during varied VSTM tasks. In contrast, PPC damage is not associated with generalized deficits in VSTM performance. Right PPC damage is known to impair spatial attention while left PPC damage is known to impair processing of numerical magnitude. The conflict between fMRI and patient data suggests several possibilities: VSTM deficits in PPC patients have not been carefully evaluated, or neuroimaging activations are epiphenomenal to VSTM task performance. In preliminary studies, I show that unilateral right PPC patients exhibit general impairment at VSTM for object, spatial and object-spatial VSTM for colors, novel shapes and tools stimulus categories. Left PPC patients do not exhibit general VSTM deficits, performing normally in the VSTM tasks. Bilateral PPC patients with simultanagnosia (the inability to see more than 1 thing at a time) are also globally impaired. Bilateral PPC also demonstrate sensitivity to experimental paradigm and performed worse in old/new VSTM recognition than in comparable recall tasks. The goal of the proposed studies is to investigate the parameters of PPC involvement in VSTM. Unresolved issues are addressed: the mechanism of VSTM impairment (encoding, maintenance, capacity, retrieval), whether recognition paradigms (old/new recognition versus 2 alternative forced-choice) affect bilateral PPC recognition performance, and whether left PPC activitations are due to involvement in processing magnitude. To accomplish this goal, I propose studies examining VSTM using complimentary approaches: neuropsychological studies of unilateral and bilateral parietal patients, as well as functional magnetic resonance imaging (fMRI) with normal subjects. PUBLIC HEALTH RELEVANCE: This set of studies is particularly relevant to the rehabilitation of parietal stroke patients. In the United States, stroke affects approximately 700,000 people annually, is the third leading cause of death, and is the leading cause of serious, long-term disability. Parietal lobe strokes are relatively common and the behavioral consequences on vision and action are devastating. In the proposed studies, VSTM impairments in parietal patients are evaluated. Deficits in VSTM have direct real-world implications relating to cognitive function. These data may provide affordable assessment measures and help guide rehabilitation strategies.