Tales Andrea, Haworth Judy, Wilcock Gordon, Newton Philip, Butler Stuart
Department of Experimental Psychology, University of Bristol, 12a Priory Road, Clifton, Bristol BS8 1TU, UK.
Neuropsychologia. 2008 Apr;46(5):1224-32. doi: 10.1016/j.neuropsychologia.2007.11.017. Epub 2007 Nov 29.
Alzheimer's disease (AD) and mild cognitive impairment (MCI) are traditionally characterised in relation to abnormalities in higher-level brain function, particularly memory. However, in the study presented here we report significant abnormality in pre-attentive visual processing in both MCI and AD compared to healthy ageing. The functional integrity of the automatic change detection system was determined by measuring the visual mismatch negativity (vMMN) component of the N2 visual event-related potential (ERP) in 8 individuals with amnestic MCI, 10 individuals with AD and 10 healthy older adult controls. Compared to healthy ageing, both the MCI and AD groups displayed a significant abnormally increased vMMN over the 140-250 ms measurement epoch although such effects were not apparent over the later 250-400 ms epoch. These novel findings support the view that deficits in brain function in both AD and MCI are not exclusively high-level and indeed that abnormal output from 'low level' or pre-attentive processes (as evinced by the abnormal vMMN) is likely to contribute to the high-level processing deficits so characteristic of these clinical disorders.
传统上，阿尔茨海默病（AD）和轻度认知障碍（MCI）的特征与高级脑功能异常有关，尤其是记忆方面。然而，在本文所呈现的研究中，我们报告称，与健康老龄化相比，MCI和AD患者在注意前视觉处理方面均存在显著异常。通过测量8名遗忘型MCI患者、10名AD患者和10名健康老年对照者的N2视觉事件相关电位（ERP）的视觉失配负波（vMMN）成分，确定了自动变化检测系统的功能完整性。与健康老龄化相比，MCI组和AD组在140 - 250毫秒测量时段内均显示出显著异常增加的vMMN，尽管在随后的250 - 400毫秒时段内这种效应并不明显。这些新发现支持了这样一种观点，即AD和MCI患者的脑功能缺陷并非仅仅局限于高级功能，实际上，“低级”或注意前过程的异常输出（如异常的vMMN所示）可能导致了这些临床疾病所特有的高级处理缺陷。
