Capitani Erminio, Laiacona Marcella, Pagani Rossella, Capasso Rita, Zampetti Patrizia, Miceli Gabriele
Neurology Unit, Milan University, S. Paolo Hospital, via Di Rudinì 8, 20146 Milan, Italy.
Brain. 2009 Apr;132(Pt 4):965-81. doi: 10.1093/brain/awp013. Epub 2009 Mar 2.
In this study we analysed the relationship between damage in the territory of the posterior cerebral artery and semantic knowledge, with special reference to category dissociations. Twenty-eight posterior cerebral artery stroke patients (18 left, 8 right and 2 bilateral posterior cerebral artery infarctions) completed a neuropsychological battery aimed at assessing semantic knowledge. The battery included picture naming, word-picture matching, a verbal semantic questionnaire and a picture reality decision task. For each participant, the lesion was reconstructed on the basis of MRI images, and was classified according to the involvement of the areas supplied by posterior cerebral artery. Defective naming scores were observed in 12 of 18 left posterior cerebral artery cases (67%), four of eight right posterior cerebral artery cases (50%), and one of two bilateral posterior cerebral artery cases (50%). Only in the bilateral posterior cerebral artery lesion case did we observe the pattern expected in pure visual agnosia, i.e. poor picture naming, poor picture reality decision, and normal verbal semantic questionnaire. Nine left posterior cerebral artery cases and two right posterior cerebral artery cases presented with poor performance on both the picture naming task and the verbal semantic questionnaire, thus suggesting semantic impairment. For 5 of the 12 left posterior cerebral artery patients who fared poorly on the naming task, biological stimuli (overall) were significantly more impaired than artifacts. In three of these five subjects, performance on plant-life stimuli was significantly less accurate than that on animals. A further left posterior cerebral artery patient presented a disproportionate impairment on plant-life stimuli only on the word-picture matching and on the questionnaire. The patterns of performance in these subjects suggest that the observed dissociations originated at the semantic level. Among left posterior cerebral artery patients, a naming deficit only occurred when damage to the fusiform gyrus extended anterior to Talairach's y-coordinate -50, and a disproportionate impairment of biological categories only when the lesion extended anterior to y = -32.5. Results show that the semantic deficit for the category of plant life is a genuine cognitive pattern, and does not depend on loss of colour knowledge. The contrast of left posterior cerebral artery strokes and herpes simplex encephalitis cases shows that the neural substrates for the semantic representation of plant life and animals are, at least in part, distinct. Middle and posterior portions of the left fusiform are crucial for the representation of plant-life knowledge, whereas left anterior temporal areas are more crucial than left posterior and basal temporal areas for the representation of knowledge about animals.
在本研究中，我们分析了大脑后动脉供血区域损伤与语义知识之间的关系，特别关注类别分离。28例大脑后动脉卒中患者（18例左侧、8例右侧及2例双侧大脑后动脉梗死）完成了一套旨在评估语义知识的神经心理学测试。该测试包括图片命名、词图匹配、言语语义问卷及图片现实判断任务。对于每位参与者，根据MRI图像重建损伤情况，并根据大脑后动脉供血区域的受累情况进行分类。18例左侧大脑后动脉病例中有12例（67%）命名得分存在缺陷，8例右侧大脑后动脉病例中有4例（50%），2例双侧大脑后动脉病例中有1例（50%）。仅在双侧大脑后动脉损伤病例中，我们观察到了纯视觉失认症预期的模式，即图片命名差、图片现实判断差及言语语义问卷正常。9例左侧大脑后动脉病例和2例右侧大脑后动脉病例在图片命名任务和言语语义问卷上均表现不佳，提示存在语义损伤。在命名任务中表现不佳的12例左侧大脑后动脉患者中，有5例的生物刺激（总体）受损明显重于人工制品。在这5例患者中的3例中，植物类刺激的表现明显不如动物类刺激准确。另有1例左侧大脑后动脉患者仅在词图匹配和问卷上对植物类刺激表现出不成比例的损伤。这些患者的表现模式表明，观察到的分离起源于语义层面。在左侧大脑后动脉患者中，只有当梭状回损伤延伸至Talairach坐标y=-50前方时才会出现命名缺陷，只有当病变延伸至y=-32.5前方时才会出现生物类别不成比例的损伤。结果表明，植物类别的语义缺陷是一种真正的认知模式，并不依赖于颜色知识的丧失。左侧大脑后动脉卒中与单纯疱疹病毒性脑炎病例的对比表明，植物和动物语义表征的神经基质至少部分是不同的。左侧梭状回的中部和后部对于植物知识的表征至关重要，而左侧颞前区对于动物知识的表征比左侧颞后区和基底颞区更为关键。
