Difference between revisions of "Exploring electroencephalography with a model inspired by quantum mechanics 2"

We first examined this model by grouping the 92 electrodes into eight regions on the scalp: Anterior L/R, Posterior L/R, Parietal L/R, Occipital L/R and the probabilities of each electrode in the region were summed to give a region-level probability. Figure 1A shows the <math>(x_j,y_j)</math> locations of each electrode, with different colours representing each of the eight groups. Figure 1B displays the frequency of entering each region, grouped by the four task conditions and two resting conditions. This reflects the normalized count of regional probabilities integrated in time. We found that each anterior region was entered more frequently while at rest than when subjects were engaged in either movie. Specifically, the anterior left and right regions had significant within stimulus change, with <math>P<0.001</math> (Tukey adjusted) for the ''Taken Rest—Taken, Taken Rest—Taken Scrambled, BYD Rest—BYD and BYD Rest—BYD Scrambled.'' This is in line with Axelrod and colleagues’ findings which showed activation in the frontal region was associated with mind wandering<ref name=":8" /><ref name=":3" />. We found frequency suppression in posterior regions, and an increase in anterior frequency in rest compared to the stimulated conditions, consistent with fMRI studies showing increased activation in the posterior cingulate cortex, and the medial prefrontal cortex during rest <ref name=":2" /><ref name=":3" /><ref name=":4">Wang RWY, Chang WL, Chuang SW, Liu IN. Posterior cingulate cortex can be a regulatory modulator of the default mode network in task-negative state. Sci. Rep. 2019;9:1–12. [PMC free article][PubMed] [Google Scholar]</ref><ref>Uddin LQ, Kelly AMC, Biswal BB, Castellanos FX, Milham MP. Functional connectivity of default mode network components: Correlation, anticorrelation, and causality. Hum. Brain Mapp. 2009;30:625–637. doi: 10.1002/hbm.20531. [PMC free article][PubMed] [CrossRef] [Google Scholar]</ref><ref>Stawarczyk D, Majerus S, Maquet P, D’Argembeau A. Neural correlates of ongoing conscious experience: Both task-unrelatedness and stimulus-independence are related to default network activity. PLoS One. 2011;6:e16997. doi: 10.1371/journal.pone.0016997.[PMC free article] [PubMed] [CrossRef] [Google Scholar]</ref><ref name=":5">Greicius, M. D., Krasnow, B., Reiss, A. L., Menon, V. & Raichle, M. E. ''Functional Connectivity in the Resting Brain: A Network Analysis of the Default Mode Hypothesis''. www.pnas.org. [PMC free article] [PubMed]</ref>. Thus, suggesting our model captures the frontal tendency associated with the brain activity while at rest.

===== Phase space =====

We also explored the average-valued phase space of this system. The phase space for each subject was plotted as the average position and momentum along the <math>x</math> direction  <math>(\langle x(t)\rangle,\langle p_x(t)\rangle)</math> or as the average position and momentum along the <math>x</math> direction  <math>(\langle y(t)\rangle,\langle p_y(t)\rangle)</math>. Figure 2 shows the centroids of the phase space scatter plots for each subject with an ellipse representing the one standard deviation confidence interval. Note that values are only reported for the intact stimuli as an analysis of variance shows the scrambled and intact movies are indistinguishable in phase space (P<math>P<0.85</math>, Tukey adjusted). Figure 2A and B show the projection of the phase space centroid onto the plane spanned by  <math>x</math> and <math>p_x</math> for “''Bang! You’re Dead''” and “''Taken''” respectively, and Fig. 2C and D (<math>y,p_y</math>) plane. The average position along the <math>y</math> axis <math>(\langle y\rangle)</math> for the intact stimulus (“BYD” and “Taken”) and their scrambled forms are significantly different from the pre-stimulus rest counterparts with <math>P<0.001</math> (Tukey adjusted) whereas the task-positive and resting centroids are indistinguishable in the <math>x</math> plane (<math>P<0.05</math>, Tukey adjusted). The averages of the group are reported in Table ​Table11 along with their standard deviations. These values are the averaged value of the centroids (average of the within stimuli centre points in Fig. 2) for the respective position/momenta within each stimulus level. As also seen in Fig. 2C and D, there is a striking difference of one order of magnitude for  <math>\langle y\rangle</math> between the resting and task conditions, yet no marked differences in <math>x</math>,<math>\langle p_x\rangle</math> , or <math>\langle p_y\rangle</math>.

<math>\Delta x(t)\Delta p_x(t)</math> and  <math>\Delta y(t)\Delta p_y(t)</math>.

Figure 4 shows the position and momentum probabilities respectively in their own basis. An animation showing how these evolve in time for the different conditions is presented in Supplementary Material 2.

To compute the values reported in Table 2, the corresponding value was found for each subject, and these were used to calculate the group average reported here.