Dynamic Connectivity Analysis Using Adaptive Window Size.

In this paper, we propose a new method to study and evaluate the time-varying brain network dynamics. The proposed method (relative intersection of confidence intervals for the imaginary component of the complex Pearson correlation coefficient) is based on an adaptive window size and the imaginary part of the complex Pearson correlation coefficient. It reduces the weaknesses of the existing method of constant sliding window analysis with narrow and wide windows. These are the low temporal precision and low reliability for short connectivity periods for wide windows, and high susceptibility to noise for narrow windows, all resulting in low estimation accuracy. The proposed method overcomes these shortcomings by dynamically adjusting the window width using the rule, which is based on the statistical properties of the area around the observed sample. In this paper, we compare the with the existing constant sliding window analysis method and describe its advantages. First, the mathematical principles are established. Then, the comparison between the existing and the proposed method using synthetic and real electroencephalography () data is presented. The results show that the proposed method has improved temporal resolution and estimation accuracy compared to the existing method and is less affected by the noise. The estimation error energy calculated for the method on synthetic signals was lower by a factor of 1.22 compared to the error of the constant sliding window analysis using narrow window size , by a factor of 2.87 compared to using wide window size , by a factor of 6.69 compared to using narrow window size , and by a factor of 4.72 compared to using wide window size . Analysis of the real signals shows the ability of the proposed method to detect a response and to detect a decrease in dynamic connectivity due to desynchronization and blockage of mu-rhythms.