<i>p</i> of two-sample KS tests of correlation coefficients in Fig 4.

<p><i>p</i> of two-sample KS tests of correlation coefficients in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0165168#pone.0165168.g004" target="_blank">Fig 4</a>.</p

Brain connectivity variation topography for group average.

<p>Each row corresponds to a rhythm, and from top to bottom, they are beta and gamma, respectively; each column represents a comparison between states, and from left to right, they are memory vs. quiet, memory vs. control, and control vs. quiet, respectively. Lines between nodes depict the link strength variation, i.e. ∆<i>L</i>, between two states. A dashed line indicates a decreasing link strength and a solid line indicates an increasing link strength. The amplitude and sign of ∆<i>L</i> are also mapped into the color of the lines. Nodes (round patches) with captions represent the change of node connectivity, i.e., ∆<i>C</i>. In detail, a larger caption size means an increase in <i>C</i> and a smaller size means a decrease, while a medium size means no discernible changes. The amplitude and sign of ∆<i>C</i> are also mapped into the color of the node.</p

EEG shuffle surrogates’ Pearson correlation.

<p>(a) Original EEG of one subject’s C3 and C4 during the memory state. (b)* Shuffled surrogates of (a). (c)-(f) Theta, alpha, beta, and gamma rhythms of (b), respectively. (g)-(j) Histogram of correlation coefficients in surrogates’ theta, alpha, beta and gamma rhythms, respectively. To obtain a reliable distribution as in (g)-(j), the original signals in (a) have been randomly shuffled 100 times independently, and (b) and (c)-(f) only depict one of the implementations. It is shown that distributions of the Pearson correlation coefficients for surrogates are symmetric sub-Gaussian, and the kurtosis increases with increasing frequency. Thus, a greater <i>r</i> for the theta rhythm does not necessarily mean a higher correlation than a lesser <i>r</i> for the gamma rhythm. The 2.5 percentile and 97.5 percentile, which are marked by vertical yellow dashed-dot lines in (g)-(j), were chosen as thresholds of corresponding rhythm. *: Although it appears that (b) is completely different from (a), especially in that there are seemingly many more spikes in (b), the histograms of (a) and (b) are exactly the same. The rough look of (b) is the result of randomly dispersing the time consecutive samples with relatively high amplitude, which compress together in (a), into different locations.</p

Experimental paradigm in memory and control tasks.

<p>The scene consisted of five sections with 2-s breaks between every two adjacent sections, and each section lasted 10 seconds, including a sequential 2-s memorization block, a 2-s retention interval, and three successive 2-s test blocks. In the memorization block, the monitor presented one object and simultaneously prompted the subject to memorize it. After the 2-s retention interval, in each test block, the subject was presented with an object and instructed to judge whether it was same with what he had seen in the memorization block and choose the corresponding option (‘yes’ or ‘no’) by clicking the mouse. The memory task and the control scene were the same except that at the beginning of the memory task, the subject was instructed to make an effort to memorize and make correct answers; for the control tasks, they were not.</p

Trans-states brain connectivity variation topography for the same subject as in Fig 4.

<p>Each row corresponds to a rhythm, and from top to bottom, they are theta, alpha, beta, and gamma respectively; each column represents a comparison between states, and from left to right, they are memory vs. quiet, memory vs. control, and control vs. quiet respectively. Lines between nodes depict the link strength variation, i.e. ∆<i>L</i>, between two states. A dashed line indicates a decreasing link strength and a solid line indicates an increasing link strength. The amplitude and sign of ∆<i>L</i> are also mapped into the color of the lines. To avoid confusion caused by drawing all 120 links among 16 leads, only links with significant differences between states, i.e., <i>p</i><0.001 in the two-sample KS test, are depicted. Nodes (round patches) with captions represent the change of node connectivity, i.e., ∆<i>C</i>. In detail, a larger caption size means an increase in <i>C</i>, and a smaller size means a decrease, while a medium size means no discernible changes. The amplitude and sign of ∆<i>C</i> are mapped into the color of the node as well. It is noted that there are certain nodes with a discernible change in <i>C</i> while there are no lines connected with them, e.g., T3 in control vs. quiet theta and F7 in memory vs. control alpha. This is no mistake: because we only plot lines for links with statistically significant differences between states while summing all links connected to the node when calculating ∆<i>C</i>, the information conveyed by the nodes and lines does not completely overlap.</p

Rhythm profiles of C3 and C4 and their corresponding correlation coefficient fluctuation.

<p>There are 12 sub figures, (a)- (i), among which from the left to right column, they are quiet, memory and control states, respectively, and from top to bottom, they are theta, alpha, beta, and gamma, respectively. Within each sub-figure, they are C3 and C4 rhythm plots and correlation coefficient fluctuation from top to bottom, respectively. In the correlation coefficient plots, the preset thresholds are depicted as horizontal yellow dash-dot lines, and dots that fall beyond the thresholds are drawn in magenta. It can be seen that there are significant differences between states for the gamma rhythm.</p

Behavioral grades of all subjects in the control (in magenta) and memory (in green) states.

<p>The grade is equal to the number of correct option clicks, with a full score being 15. In the end, all subjects received scores of no less than 13 in the memory task and no more than 8 in the control state.</p