School of Psychology, NUI, Galway, Ireland.
Brain Res. 2012 Mar 22;1445:1-10. doi: 10.1016/j.brainres.2012.01.027. Epub 2012 Jan 20.
The current study examined electrophysiological entropy in younger adults, older adults, and older cognitively declined adults across four experimental conditions - eyes closed, eyes open, and during both encoding and recognition of words in a memory task. We hypothesised reduced entropy in older declined adults relative to both older controls and younger adults, with the largest group differences in entropy expected during the encoding and recognition phases of the experiment. We also hypothesised greater hemispheric asymmetry in younger adults compared with older controls and older declined adults. Results revealed significant increases in entropy from eyes closed to eyes open to task. Young adults showed higher entropy in the right relative to the left hemisphere in the temporal lobe and higher entropy in the left relative to the right hemisphere in the parietal lobe. Old cognitively declined adults showed no significant differences between right and left hemisphere entropy. There was a trend whereby older declined adults showed lower entropy than older controls in the frontal lobe, this difference being largest in the left hemisphere during the encoding phase of the experiment. Results indicate that measures of entropy are sensitive to information processing demands and that higher cognitive performance may not be a simple function of entropy level, but rather a combination of level and range, or differentiated range of entropy states across the brain.
本研究在四个实验条件下（闭眼、睁眼、在记忆任务中编码和识别单词期间），检测了年轻成年人、老年成年人和认知衰退老年人的脑电熵。我们假设与老年对照组和年轻成年人相比，认知衰退老年人的熵值降低，并且预计在实验的编码和识别阶段，熵值的组间差异最大。我们还假设与老年对照组和认知衰退老年人相比，年轻成年人的大脑半球间的不对称性更大。结果显示，熵值从闭眼到睁眼再到任务期间呈显著增加趋势。年轻成年人在颞叶中右半球的熵值高于左半球，在顶叶中左半球的熵值高于右半球。认知衰退老年人的右半球和左半球的熵值之间没有显著差异。有一种趋势表明，与老年对照组相比，认知衰退老年人在额叶的熵值较低，在实验的编码阶段，这种差异在左半球最大。结果表明，熵值的测量方法对信息处理需求敏感，并且较高的认知表现可能不是熵值水平的简单函数，而是水平和范围的组合，或者是大脑中熵状态的差异范围。
