File:Increase of Cross-Regional Phase-Amplitude Coupling at Near-Death.jpg

English: "Surge of crPAC in the dying brain. (A) crPAC of gamma oscillations (30 to 250 Hz) in the right somatosensory cortex (C4) with the lower frequency (1 to 50 Hz) waves in the right ventrolateral prefrontal cortex (F8) displayed for Pt1. (B) Spatial and temporal dynamics of crPAC was displayed between amplitude of gamma2 wave in the posterior brain (C3, C4, T3, T4, T5, T6, P3, P4, O1 and O2) and phase of beta wave in the prefrontal lobes (Fp1, F7, F3, Fp2, F4, F8) in Pt1. The color bar indicates the strength of the beta/gamma2 coupling. (C) crPAC during the initial phase of the near-death states (S2 and S3) is readily detectable only between the somatosensory cortices (C3 and C4) and the prefrontal (Fp1, F7, F3, F4, F8) areas in both Pt1 and Pt3. (D) Beta-gamma2 crPAC between somatosensory cortices (C3 and C4) and the frontal areas of the brain at early stages of dying process in both Pt1 and Pt3." "We determined phase-amplitude coupling of lower frequency bands (<30 Hz) in the frontal lobes with higher frequency waves (>30 Hz) in the posterior areas (C3, C4, P3, P4, T3, T4, T5, T6, O1, and O2) (Fig. 3) and uncovered the earlier coupling in S2 and S3 between the right SSC (C4) and right VLPFC (F8), with further increase in S4, S6, S7, and S9 in Pt1 (Fig. 3 A and B). Frequency of cross-regionally coupled gamma oscillations peaked higher than 150 Hz (Fig. 3A), like the regional PAC (Fig. 2A). In this study, we restricted our focus on the cross-regional PAC (crPAC) between the amplitude of gamma1 (25 to 55 Hz), gamma2 (80 to 150 Hz), and the phase of lower frequency bands (theta, alpha, and beta). During the early stages of the near-death period (S2 and S3), the only beta/gamma2 crPAC above the threshold across the entire brain was between the SSC (C4 in S2, and C3 and C4 in S3) and the right frontal lobes (F4 and F8) in Pt1 (Fig. 3B). During the period when the atrial pacemaker was triggered (S4, S6, S7), the highest beta/gamma2 crPAC signal was between the gamma2 oscillations in the left posterior areas (T5, P3, O1) and the beta waves from the right frontal areas (Fp2, F8, F4) (Fig. 3B). In later dying stages, elevated crPAC was detected between left anterior-mid temporal lobe (T3) and prefrontal areas (F3, Fp2, F4, F8) in S8 and between the electrodes in the right temporal (T4, T6) and parietal (P4) areas with those in prefrontal areas in S9 (Fig. 3B). Interestingly, the highest coupling during S4, S6, and S7, was interhemispheric between the right prefrontal areas and left posterior areas, whereas the highest coupling in S9 was intrahemispheric between the right prefrontal areas and right posterior (T4, T6, P4) areas (Fig. 3B). Of the remaining patients, Pt3 was the only other one who showed elevated crPAC at near-death (right panel in Fig. 3C). In fact, beta/gamma2 crPAC between the SSCs (C3 and C4) and the frontal areas (Fp1, F7, F3, F8) represented the only coupling detectable across the entire brain during the near-death period for Pt3. Of the posterior areas during the early phase of dying for both Pt1 and Pt3, SSCs appeared to be the only cortical regions that displayed crPAC with frontal lobes (Fig. 3C). Further analysis showed that during the initial dying phase (S2 and S3), crPAC for Pt3 was restricted to the electrodes within the same hemisphere of the brain (Fig. 3 D, Right) while crPAC for Pt1 was detected intrahemispherically as well as interhemispherically (Fig. 3 D, Left)."