The nature of parietal involvement in visual short-term memory

描述(由申请人提供)：本修订方案的目的是进一步详细说明顶叶后皮质(PPC)在视觉短期记忆(VSTM)中的作用。许多功能磁共振成像(FMRI)研究观察到在不同的VSTM任务中双侧PPC的激活。相比之下，PPC损伤与VSTM性能的普遍缺陷无关。已知右侧PPC损伤会损害空间注意，而左侧PPC损伤会损害数字加工。FMRI和患者数据之间的冲突暗示了几种可能性：PPC患者的VSTM缺陷没有得到仔细的评估，或者神经成像激活是VSTM任务表现的附属品。在初步研究中，我发现单侧右侧PPC患者在VSTM的客体、空间和客体-空间VSTM在颜色、新形状和工具刺激类别上表现出普遍的损害。左侧PPC患者没有表现出一般的VSTM缺陷，在VSTM任务中表现正常。同时失认的双侧PPC患者(不能同时看到一件以上的东西)也是全球性的损害。双侧PPC也表现出对实验范式的敏感性，在旧的/新的VSTM再认中的表现比在可比的回忆任务中更差。这项研究的目的是调查VSTM中PPC参与的参数。讨论了尚未解决的问题：VSTM损伤的机制(编码、维持、容量、提取)，识别范式(旧/新识别与两种替代强迫选择)是否影响双边PPC识别性能，以及左侧PPC激活是否由于参与加工大小而引起。为了实现这一目标，我建议使用互补的方法研究VSTM：单侧和双侧顶叶患者的神经心理学研究，以及正常受试者的功能磁共振成像(FMRI)。公共卫生相关性：这组研究与顶叶中风患者的康复特别相关。在美国，中风每年影响大约70万人，是第三大致死原因，也是导致长期严重残疾的首要原因。顶叶中风相对常见，对视力和行动的行为后果是毁灭性的。在拟议的研究中，对顶叶患者的VSTM损害进行了评估。VSTM缺陷在现实世界中与认知功能有直接关系。这些数据可能会提供负担得起的评估措施，并有助于指导康复战略。

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.