MR INFORMATION PROCESSING

拟议工作的主要目的是确定第一个具体的 大脑中发生的功能和解剖学变化 HIV感染，在无CNS并发症的情况下 机会性感染 根据之前解剖学上的发现 研究记忆受损的主题，我们提出了一个新的解释， 对这些受试者进行知觉启动研究的结果。 简而言之， 我们获得的证据表明，先前解释的表现模式， 受试者的边缘系统和新皮层损伤的术语忽略了 伴随纹状体损伤的重要影响。 由于 证据表明HIV+受试者的纹状体结构经常受损， 并且可能在边缘系统和新皮层结构中有额外的损伤， 我们以前的研究结果被认为是重要的 对HIV+患者的影响。 我们预测，在早期阶段，艾滋病毒- 相关的脑病将与特定的模式， 反映纹状体和颞叶边缘效应的行为缺陷。 免疫抑制的HIV+受试者的尾状核损伤是预期的 在知觉运动任务上产生障碍，并导致缓慢的 知觉识别和词汇通达。 单独来看，尾状核损伤 随后的感知运动和词汇缺陷预计将 与知觉和词汇启动任务的过度启动有关，但是 正常区分最近提出的新材料， 再认记忆任务 另一方面，颞叶边缘损伤， 预期会导致启动减少和识别记忆减少。 然而，当尾状核和颞叶边缘系统都有损伤时， 受试者预期表现出差的知觉运动和词汇 加工和识别记忆差，但正常启动。 在这 在某些情况下，有可能表明，显然是正常的启动是由于 由于词汇和知觉受损， 材料的处理，加上由于 颞叶边缘损伤 将进行两项平行研究， 从这个模型中产生的特定假设： 特定结构中的体积损失（如在成像系统内测量的） 核心）将与任务表现相关;和功能性MRI研究， 这些结构中激活水平的改变 将与动物的行为和解剖学指标相关， 脑病 75名艾滋病毒阳性受试者和45名年龄和教育程度- 将检查匹配的对照。 一系列以电脑为媒介， 涉及心理学、知觉和词汇的实验任务 加工;词汇和知觉启动。明确的回忆， 将进行识别记忆。 此外，功能性MR 激活研究将在受试者计划的时间进行 MRI随访。 解剖学和激活研究将针对 尾状核（CN）和海马及邻近的海马旁回 （H/PG）

The major aim of the proposed work is to define the first specific functional and anatomical changes that occur in the brain in association with HIV infection, in cases uncomplicated by the presence of CNS opportunistic infections. Based on findings from a previous anatomical study of memory-impaired subjects, we have proposed a novel interpretation of the results of perceptual priming studies in such subjects. In brief, we obtained evidence that patterns of performance previously interpreted in terms of the subjects' limbic and neocortical damage neglected the important influence of concomitant striatal damage. Since there is evidence that HIV+ subjects frequently have damage in striatal structures, and may have additional damage in limbic and neocortical structures, the findings of our previous study are considered to have important implications for HIV+ subjects. We predict that, in the early stages, HIV- related encephalopathy will be associated with a specific pattern of behavioral deficits reflecting striatal and temporal limbic effects. Damage to the caudate nucleus in immunosuppressed HIV+ subjects is expected to produce impairment on perceptual-motor tasks, and to result in slowed perceptual identification and lexical access. In isolation, caudate damage and the subsequent perceptual-motor and lexical deficits are expected to be associated with hyperpriming on perceptual and lexical priming tasks, but normal discrimination of recently presented from novel material in recognition memory tasks. Temporal lobe limbic damage, on the other hand, is expected to result in reduced priming and reduced recognition memory. However, when both caudate and temporal limbic damage are present, the subjects are expected to exhibit poor perceptual-motor and lexical processing and poor recognition memory, but normal priming. In this instance it will be possible to show that apparently normal priming is due to augmentation of priming effects due to impaired lexical and perceptual processing of the material, combined with decrements in priming due to temporal limbic damage. Two parallel studies will be conducted to test specific hypotheses arising from this model: a neuroanatomical study in which volume losses in specific structures (as measured within the Imaging Core) will be correlated with task performance; and a functional MRI study, in which alterations in the level of activation within these structures will be correlated with behavioral and anatomical indices of encephalopathy. Seventy-five HIV+ subjects and 45 age- and education- matched controls will be examined. A series of computer-mediated, experimental tasks involving psychomotor, perceptual, and lexical processing; lexical and perceptual priming.; and explicit recall and recognition memory will be conducted. In addition, functional MR activation studies will be conducted at the time of the subjects' scheduled MRI follow-ups. The anatomical and activation studies will target the caudate nucleus (CN) and the hippocampus and adjacent parahippocampal gyrus (H/PG)