TY - JOUR
T1 - Local awakening
T2 - Regional reorganizations of brain oscillations after sleep
AU - Tsai, Pei Jung
AU - Chen, Sharon Chia Ju
AU - Hsu, Chun Yao
AU - Wu, Chang-Wei
AU - Wu, Yu Chin
AU - Hung, Ching Sui
AU - Yang, Albert C.
AU - Liu, Po Yu
AU - Biswal, Bharat
AU - Lin, Ching Po
PY - 2014/11/5
Y1 - 2014/11/5
N2 - Brain functions express rhythmic fluctuations accompanied by sleep and wakefulness each day, but how sleep regulates brain rhythms remains unclear. Following the dose-dependent local sleep concept, two succeeding questions emerge: (1) is the sleep regulation a network-specific process; and (2) is the awakening state dependent on the previous sleep stages? To answer the questions, we conducted simultaneous EEG and fMRI recordings over 22 healthy male participants, along pre-sleep, nocturnal sleep and awakening. Using paired comparisons between awakening and pre-sleep conditions, three scenarios of the regional specificity were demonstrated on awakening: (1) the default-mode and hippocampal networks maintained similar connectivity and spectral power; (2) the sensorimotor network presented reduced connectivity and spectral power; and (3) the thalamus demonstrated substantially enhanced connectivity to the neo-cortex with decreased spectral power. With regard to the stage effect, the deep sleep group had significant changes in both functional connectivity and spectral power on awakening, whereas the indices of light sleep group remained relatively quiescent after sleep. The phenomena implied that slow-wave sleep could be key to rebooting the BOLD fluctuations after sleep. In conclusion, the regional specificity and the stage effect were verified in support of the local awakening concept, indicating that sleep regulation leads to the reorganization of brain networks upon awakening.
AB - Brain functions express rhythmic fluctuations accompanied by sleep and wakefulness each day, but how sleep regulates brain rhythms remains unclear. Following the dose-dependent local sleep concept, two succeeding questions emerge: (1) is the sleep regulation a network-specific process; and (2) is the awakening state dependent on the previous sleep stages? To answer the questions, we conducted simultaneous EEG and fMRI recordings over 22 healthy male participants, along pre-sleep, nocturnal sleep and awakening. Using paired comparisons between awakening and pre-sleep conditions, three scenarios of the regional specificity were demonstrated on awakening: (1) the default-mode and hippocampal networks maintained similar connectivity and spectral power; (2) the sensorimotor network presented reduced connectivity and spectral power; and (3) the thalamus demonstrated substantially enhanced connectivity to the neo-cortex with decreased spectral power. With regard to the stage effect, the deep sleep group had significant changes in both functional connectivity and spectral power on awakening, whereas the indices of light sleep group remained relatively quiescent after sleep. The phenomena implied that slow-wave sleep could be key to rebooting the BOLD fluctuations after sleep. In conclusion, the regional specificity and the stage effect were verified in support of the local awakening concept, indicating that sleep regulation leads to the reorganization of brain networks upon awakening.
KW - Functional connectivity
KW - Local awakening
KW - Local sleep
KW - Simultaneous EEG-fMRI recordings
KW - Spectral power
KW - Thalamo-cortical connectivity
UR - http://www.scopus.com/inward/record.url?scp=84908337662&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84908337662&partnerID=8YFLogxK
U2 - 10.1016/j.neuroimage.2014.07.032
DO - 10.1016/j.neuroimage.2014.07.032
M3 - Article
C2 - 25067818
AN - SCOPUS:84908337662
SN - 1053-8119
VL - 102
SP - 894
EP - 903
JO - NeuroImage
JF - NeuroImage
IS - P2
ER -