Reuter-Lorenz Patricia A, Mikels Joseph A
Department of Psychology, University of Michigan, 525 East University Avenue, Ann Arbor, MI 48109-1109, USA.
Neuropsychologia. 2005;43(9):1307-17. doi: 10.1016/j.neuropsychologia.2004.12.007. Epub 2005 Feb 9.
It has been proposed that features of Alzheimer-type dementia (AD) reflect a breakdown in cortical connectivity that can be likened to a disconnection syndrome. One hypothesized consequence of this pathology is that AD patients should be disproportionally impaired on measures of interhemispheric transfer. However, there is a paucity of studies bearing on this prediction. We report the results from two measures of interhemispheric interaction obtained from healthy younger and older adults, and older adults with probable AD. One measure examined speeded simple manual responses to a lateralized light flash (i.e., the Poffenberger task) and the other examined the interhemispheric coordination of computational resources using within and across hemifield variants of visual letter-matching tasks. AD patients show an overall impairment of performance on both intra and interhemispheric conditions in all tasks. However, there is no indication of disproportionate alteration of interhemispheric processes mediating either visuomotor transfer or visual letter-matching and the allocation of computational resources. The results, therefore, call into question the appropriateness of a "split-brain" model for AD, at least in the domain of visual processing. Although the results are not specifically diagnostic of a disconnection syndrome, they are consistent with the possibility of a breakdown of cortico-cortical connectivity both within and between the hemispheres in AD.
有人提出，阿尔茨海默病型痴呆（AD）的特征反映了皮质连接的崩溃，这可以被比作一种失连接综合征。这种病理学的一个假设后果是，AD患者在半球间传递的测量上应该受到不成比例的损害。然而，关于这一预测的研究很少。我们报告了从健康的年轻人和老年人以及可能患有AD的老年人那里获得的两种半球间相互作用测量的结果。一种测量方法是对侧向闪光的快速简单手动反应（即波芬伯格任务），另一种测量方法是使用视觉字母匹配任务的半视野内和跨半视野变体来检查计算资源的半球间协调。AD患者在所有任务的半球内和半球间条件下的表现都存在整体损害。然而，没有迹象表明介导视运动传递或视觉字母匹配以及计算资源分配的半球间过程有不成比例的改变。因此，这些结果至少在视觉处理领域对AD的“裂脑”模型的适用性提出了质疑。虽然这些结果不能具体诊断失连接综合征，但它们与AD中半球内和半球间皮质-皮质连接崩溃的可能性是一致的。
