Analysis of the complexity of EEG during the short-term memory task

By using fractal dimension and sample entropy, we investigated the complexity electroencephalogram (EEG) during an activity that uses working memory. We conduct a short-term memory test and a calculation task and analyzed 1.0s EEG data from 4 phases (resting, encoding, retrieval and calculation phase). As a result, fractal dimension analysis can reflect the activity of the working memory better than sample entropy analysis. Moreover, in order to investigate the relationship between the fractal dimension value and the power of theta band (4-8 Hz) in the frontal region, we conducted a correlation coefficient analysis. The result showed that increase of the power of theta band and decrease of fractal dimension value has relatively high correlation. In conclusion, the activity of working memory in frontal part may be able to be captured by fractal dimension analysis.