Department of Neurology, University of California Los Angeles, Los Angeles, CA 90095, USA.
J Magn Reson Imaging. 2013 Jul;38(1):36-45. doi: 10.1002/jmri.23961. Epub 2012 Dec 7.
To explore the use of approximate entropy (ApEn) as an index of the complexity and the synchronicity of resting state blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) in normal aging and cognitive decline associated with familial Alzheimer's disease (fAD).
Resting state BOLD fMRI data were acquired at 3T from two independent cohorts of subjects consisting of healthy young (age 23 ± 2 years, n = 8) and aged volunteers (age 66 ± 3 years, n = 8), as well as 22 fAD associated subjects (14 mutation carriers, age 41.2 ± 15.8 years; and eight nonmutation carrying family members, age 28.8 ± 5.9 years). Mean ApEn values were compared between the two age groups and correlated with cognitive performance in the fAD group. Cross-ApEn (C-ApEn) was further calculated to assess the asynchrony between precuneus and the rest of the brain.
Complexity of brain activity measured by mean ApEn in gray and white matter decreased with normal aging. In the fAD group, cognitive impairment was associated with decreased mean ApEn in gray matter as well as decreased regional ApEn in right precuneus, right lateral parietal regions, left precentral gyrus, and right paracentral gyrus. A pattern of asynchrony between BOLD fMRI series emerged from C-ApEn analysis, with significant regional anti-correlation with cross-correlation coefficient of functional connectivity analysis.
ApEn and C-ApEn may be useful for assessing the complexity and synchronicity of brain activity in normal aging and cognitive decline associated with neurodegenerative diseases.
探索近似熵（ApEn）作为一种指标，用于研究正常衰老和与家族性阿尔茨海默病（fAD）相关认知能力下降过程中静息状态血氧水平依赖（BOLD）功能磁共振成像（fMRI）的复杂性和同步性。
在 3T 磁共振扫描仪上采集来自两个独立的研究对象队列的静息状态 BOLD fMRI 数据，这两个队列包括健康的年轻志愿者（年龄 23 ± 2 岁，n = 8）和老年志愿者（年龄 66 ± 3 岁，n = 8），以及 22 名与 fAD 相关的研究对象（14 名突变携带者，年龄 41.2 ± 15.8 岁；8 名非突变携带者的家庭成员，年龄 28.8 ± 5.9 岁）。比较两组之间的平均 ApEn 值，并与 fAD 组的认知表现相关。进一步计算交叉 ApEn（C-ApEn）以评估楔前叶与大脑其他区域之间的失同步。
通过平均 ApEn 测量的大脑活动复杂性在灰质和白质中随着正常衰老而降低。在 fAD 组中，认知障碍与灰质中平均 ApEn 降低以及右侧楔前叶、右侧顶侧区域、左侧中央前回和右侧旁中央回的局部 ApEn 降低有关。C-ApEn 分析显示出一种 BOLD fMRI 系列之间的失同步模式，与功能连接分析的交叉相关系数的区域反相关具有显著相关性。
ApEn 和 C-ApEn 可能有助于评估正常衰老和与神经退行性疾病相关的认知能力下降过程中大脑活动的复杂性和同步性。
