Penniello M J, Lambert J, Eustache F, Petit-Taboué M C, Barré L, Viader F, Morin P, Lechevalier B, Baron J C
INSERM U.320, CYCERON, Caen, France.
Brain. 1995 Jun;118 ( Pt 3):697-706. doi: 10.1093/brain/118.3.697.
A dissociation in the central processes of spelling, with preferentially lexical over phonological impairment, frequently affects patients with early Alzheimer's disease. The aim of this work was to test whether dissociations in the language domain in Alzheimer's disease can be exploited with PET to assess the neural basis of cognition. To this end, we studied the functional neuroanatomy of writing impairment in Alzheimer's disease by means of PET measurements of the local cerebral glucose utilization and neuropsychological tests specially designed to assess the phonological and lexical components of writing. We analysed the performance in written spelling of irregular words and non-words of 11 right-handed patients with mild-to-moderate Alzheimer's disease. For each patient, we calculated a residual phonological score and a residual lexical score, based on a cognitive interpretation of the errors according to the item category. In each of these 11 patients, using PET, we measured the resting-state utilization of glucose in the left supramarginal gyrus and the left angular gyrus, two cortical regions selected a priori because of their presumed role in the central processes for spelling, and identified on CT scans obtained according to stereotaxic references and coregistered with PET. To assess the relationships between the neuropsychological scores and the metabolic data, we used the 'ratio paradigm', the sensitivity of which has been previously documented in cognitive-metabolic correlative PET studies of Alzheimer's disease that were less focused than the present study in both cognitive and anatomical terms. We found a highly significant positive correlation between phonological score:lexical score neuropsychological ratios and corresponding supramarginal gyrus:angular gyrus metabolic ratios. These findings further support the role of these two left-sided temporo-parietal regions in the central processes of writing and show that the neuropsychological dissociations in early Alzheimer's diseases can be exploited to further our understanding of the functional neuroanatomy of cognitive operations. The role of focal, as compared with more diffuse, brain damage in the development of impaired written language of central origin in Alzheimer's disease is also discussed.
拼写中枢过程的分离，即词汇损伤优先于语音损伤，经常影响早期阿尔茨海默病患者。这项研究的目的是测试PET是否能够利用阿尔茨海默病语言领域的分离来评估认知的神经基础。为此，我们通过对局部脑葡萄糖利用情况进行PET测量以及专门设计用于评估书写语音和词汇成分的神经心理学测试，研究了阿尔茨海默病书写障碍的功能神经解剖学。我们分析了11名右利手轻度至中度阿尔茨海默病患者在书写不规则单词和非单词时的表现。对于每位患者，我们根据错误的项目类别进行认知解释，计算出残余语音分数和残余词汇分数。在这11名患者中的每一位中，我们使用PET测量了左顶上回和左角回的静息态葡萄糖利用情况，这两个皮质区域由于其在拼写中枢过程中的假定作用而预先选定，并在根据立体定向参考获得的CT扫描上识别出来，并与PET进行配准。为了评估神经心理学分数与代谢数据之间的关系，我们使用了“比率范式”，其敏感性先前已在阿尔茨海默病的认知 - 代谢相关PET研究中得到记录，这些研究在认知和解剖学方面的关注程度均低于本研究。我们发现语音分数与词汇分数的神经心理学比率和相应顶上回与角回的代谢比率之间存在高度显著的正相关。这些发现进一步支持了这两个左侧颞顶区域在书写中枢过程中的作用，并表明早期阿尔茨海默病中的神经心理学分离可用于加深我们对认知操作功能神经解剖学的理解。还讨论了与更广泛的脑损伤相比，局灶性脑损伤在阿尔茨海默病中枢性起源的书面语言障碍发展中的作用。
