Study of the Brain Functional Connectivity Processes During Multi-Movement States of the Lower Limbs

Figure 1. Experimental paradigm: (a) EEG channel layout and (b) protocol timeline.

Figure 2. EEG-preprocessing steps.

Figure 3. The calculation process of TFCMI. (a) The raw EEG obtained from 58 channels was first filtered by a bandpass filter (with 0.1–50Hz passband). (b) The filtered signals of each channel were processed using the Morlet wavelet transformation to obtain time–frequency power maps within the selected frequency band (16–25 Hz). (c) The averaged power signal for each channel was created by averaging the individual time–frequency maps across the selected frequency band. (d) The 58 × 58 TFCMI map was obtained by calculating the TFCMI values from the averaged powers between any two channels. (e) The accumulated coupling strengths can be represented by summing the rows or columns of TFCMI maps and depicted as a 58-channel topographic map.

Figure 4. The topographic maps of the averaged accumulated coupling strength of eight subjects: (a) delta, (b) theta, and (c) gamma bands. Aft is the standing after W + BCI; Pre is the standing before W.

Figure 5. The accumulated coupling connectivity difference between two states, including the modulation of 10-to-1 connectivity from Pre to W, W to WB, and Pre to Aft: (a) delta band, (b) theta band, (c) gamma band. Aft is the standing after W + BCI; Pre is the standing before W.

Figure 6. The statistical analysis of the connectivity network in TFCMI values for the four states: (a) delta, (b) theta, and (c) gamma-band; the green balls represent the within-region connectivity, and the lines are the significant between-region connectivity.