摘要
探讨轻度认知功能障碍患者(MCI)工作记忆状态下脑电能量及皮质联络功能的变化特征。被试为从社区选取的35名轻度认知功能障碍患者和34名健康志愿者。采用简单计算回忆方法,结果发现工作记忆加工过程中会引起4.0～18.0Hz范围内功率值的改变,且MCI组高于正常对照组;MCI患者在中央、顶、颞叶的半球间相干系数均显著高于正常对照组。研究结果提示MCI患者可能存在中央、顶、颞叶皮层的功能减退,工作记忆状态下通过代偿机制仍能维持加工的有效性。
Introduction The clinical condition characterized by objective memory disturbances in the absence of other cognitive deficits is called mild cognitive impairment （MCI）. MCI is one of the risk factors of Alzheimer＇s disease （AD）. The study of cognitive impairment in patients with MCI, particularly memory deficiency, may aid in obtaining clues of early stage of AD. Many studies have reported that working memory plays an important role in learning, calculating, reasoning, and verb comprehension in cognitive processing;, hence, it is important to study working memory processing in MCI. The aim of the present study was to investigate the characteristics of EEG power and coherence in patients with MCI during working memory processing.
Method Subjects that included 35 MCI patients according to the DSM-Ⅳ criteria （mean age 61.6 years, SD 7,2） and 34 health controls （mean age 59.1 years, SD 5.4） were selected from the community. All subjects performed a simple calculation and recall task with 3 levels of working memory load, with a simultaneous recording of the EEG signal. The spectral EEG power was computed over delta （1.0 -3.5 Hz）, theta （4.0 -7.5 Hz）, alphal （8.0 -8.5 Hz）, alpha2 （9.0 -13.0 Hz）, betal （13.5 -18.0 Hz）, and beta2 （18.5 -30.0 Hz） frequency bands and was compared between the rest stage and the working memory processing stage by a 2×3 MANOVA. Post hoe test analyzed the differences between each 2 levels of working memory load during the task processing. The EEG and the interhemisphere EEG coherence of frontal （F3-F4）, central （C3-C4）, parietal （P3-P4）, temporal （T5-T6） and occipitals （O1-O2） were compared between MCI patients and health controls.
Results （1） Spectral EEG power analysis： The spectral EEG power over delta, theta, alphal, alpha2, and betal bands was significantly higher in the working memory stage than that in the rest stage. The group （MCI and controls）-state （3 task levels） interaction was not significant. Post hoc analysis indicated that there was no significant difference between each 2 levels during the working memory stage. The spectral EEG power of MCI patients over delta, theta, alphal, alpha2, and betal bands was significantly higher than that of the normal controls during the task processing. （2） Coherence analysis： The interhemisphere coherence in the rest state showed no significant difference between MCI patients and the normal controls. Theta （4.0 -7.5 Hz）, alphal （8.0 -8.5 Hz）, and alpha2 （9.0 - 13.0 Hz） frequency bands were selected to investigate the differences in interhemisphere coherence between MCI and controls during the working memory processing stage. There was significantly higher inter-hemisphere coherence in central （C3-CA）, parietal （P3-P4）, temporal （T5-T6） sites of MCI patients than that of the normal controls during working memory processing.
Conclusion Working memory processing was related to delta （1.0 -3.5 Hz）, theta （4.0 - 7.5 Hz）, alphal （8. 0-8.5Hz）, alpha2 （9.0 - 13.0 Hz）, and betal （13.5 - 18.0 Hz） frequency bands. MCI patients may have impairment in the central, parietal, and temporal cortex. During working memory processing. MCI patients may mobilize a compensatory mechanism that serve to maintain processing effectiveness while concealing underlying reduction in processing efficiency.
出处
《心理学报》
CSSCI
CSCD
北大核心
2007年第4期638-647,共10页
Acta Psychologica Sinica
基金
浙江省科技计划资助项目(2003B070)
关键词
功率值
相干性
轻度认知功能障碍
工作记忆.
spectral power, coherence, mild cognitive impairment, working memory.
