Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, 401 Quarry Road, Stanford, CA 94305, USA.
Neuropsychologia. 2010 Mar;48(4):1133-43. doi: 10.1016/j.neuropsychologia.2009.12.015. Epub 2009 Dec 16.
HIV-1 infection affects white matter circuits linking frontal, parietal, and subcortical regions that subserve visuospatial attention processes. Normal perception requires the integration of details, preferentially processed in the left hemisphere, and the global composition of an object or scene, preferentially processed in the right hemisphere. We tested whether HIV-related callosal white matter degradation contributes to disruption of selective lateralized visuospatial and attention processes. A hierarchical letter target detection paradigm was devised, where large (global) letters were composed of small (local) letters. Participants were required to identify target letters among distractors presented at global, local, both or neither level. Attention was directed to one (global or local) or both levels. Participants were 21 HIV-1 infected and 19 healthy control men and women who also underwent Diffusion Tensor Imaging (DTI). HIV-1 participants showed impaired hierarchical perception owing to abnormally enhanced global facilitation effects but no impairment in attentional control on local-global feature selection. DTI metrics revealed poorer fiber integrity of the corpus callosum in HIV-1 than controls that was more pronounced in posterior than anterior regions. Analysis revealed a double dissociation of anterior and posterior callosal compromise in HIV-1 infection: compromise in anterior but not posterior callosal fiber integrity predicted response conflict elicited by global targets, whereas compromise in posterior but not anterior callosal fiber integrity predicted response facilitation elicited by global targets. We conclude that component processes of visuospatial perception are compromised in HIV-1 infection attributable, at least in part, to degraded callosal microstructural integrity relevant for local-global feature integration.
HIV-1 感染会影响连接额叶、顶叶和皮质下区域的白质回路，这些区域负责视觉空间注意过程。正常的感知需要整合细节，这些细节优先在左半球处理，以及物体或场景的整体构成，这些优先在右半球处理。我们测试了 HIV 相关的胼胝体白质降解是否会导致选择性的侧化视觉空间和注意力过程的中断。设计了一个层次字母目标检测范式，其中大（全局）字母由小（局部）字母组成。参与者需要在全局、局部、两者或两者都没有的水平上识别目标字母。注意力被引导到一个（全局或局部）或两个水平。参与者包括 21 名 HIV-1 感染者和 19 名健康的男性和女性对照者，他们还接受了弥散张量成像（DTI）检查。HIV-1 参与者表现出层次知觉受损，原因是全局促进效应异常增强，但在局部-全局特征选择上注意力控制没有受损。DTI 指标显示，HIV-1 患者的胼胝体纤维完整性比对照组差，后部比前部更明显。分析显示，HIV-1 感染中的胼胝体前部和后部的损伤存在双重分离：前部胼胝体纤维完整性受损而不是后部胼胝体纤维完整性受损，预测了全局目标引起的反应冲突，而后部胼胝体纤维完整性受损而不是前部胼胝体纤维完整性受损，预测了全局目标引起的反应促进。我们得出结论，HIV-1 感染会损害视觉空间感知的组成过程，至少部分原因是与局部-全局特征整合相关的胼胝体微观结构完整性受损。
