PMID- 29991811
OWN - NLM
STAT- MEDLINE
DCOM- 20191125
LR  - 20240328
IS  - 2045-2322 (Electronic)
IS  - 2045-2322 (Linking)
VI  - 8
IP  - 1
DP  - 2018 Jul 10
TI  - Circadian challenge of astronauts' unconscious mind adapting to microgravity in 
      space, estimated by heart rate variability.
PG  - 10381
LID - 10.1038/s41598-018-28740-z [doi]
LID - 10381
AB  - It is critical that the regulatory system functions well in space's microgravity. 
      However, the "intrinsic" cardiovascular regulatory system (beta), estimated by the 
      fractal scaling of heart rate variability (HRV) (0.0001-0.01 Hz), does not adapt 
      to the space environment during long-duration (6-month) space flights. 
      Neuroimaging studies suggest that the default mode network (DMN) serves a broad 
      adaptive purpose, its topology changing over time in association with different 
      brain states of adaptive behavior. Hypothesizing that HRV varies in concert with 
      changes in brain's functional connectivity, we analyzed 24-hour HRV records from 
      8 healthy astronauts (51.8 +/- 3.7 years; 6 men) on long (174.5 +/- 13.8 days) space 
      missions, obtained before launch, after about 21 (ISS01), 73 (ISS02), and 156 
      (ISS03) days in space, and after return to Earth. Spectral power in 8 frequency 
      regions reflecting activity in different brain regions was computed by maximal 
      entropy. Improved beta (p < 0.05) found in 4 astronauts with a positive activation 
      in the "HRV slow-frequency oscillation" (0.10-0.20 Hz) occurred even in the 
      absence of consciousness. The adaptive response was stronger in the evening and 
      early sleep compared to morning (p = 0.039). Brain functional networks, the DMN 
      in particular, can help adapt to microgravity in space with help from the 
      circadian clock.
FAU - Otsuka, Kuniaki
AU  - Otsuka K
AD  - Executive Medical Center, Totsuka Royal Clinic, Tokyo Women's Medical University, 
      Tokyo, Japan. frtotk99@ba2.so-net.ne.jp.
AD  - Halberg Chronobiology Center, University of Minnesota, Minneapolis, Minnesota, 
      USA. frtotk99@ba2.so-net.ne.jp.
FAU - Cornelissen, Germaine
AU  - Cornelissen G
AD  - Halberg Chronobiology Center, University of Minnesota, Minneapolis, Minnesota, 
      USA.
FAU - Kubo, Yutaka
AU  - Kubo Y
AD  - Department of Medicine, Tokyo Women's Medical University, Medical Center East, 
      Tokyo, Japan.
FAU - Shibata, Koichi
AU  - Shibata K
AD  - Department of Medicine, Tokyo Women's Medical University, Medical Center East, 
      Tokyo, Japan.
FAU - Hayashi, Mitsutoshi
AU  - Hayashi M
AD  - Department of Medicine, Tokyo Women's Medical University, Medical Center East, 
      Tokyo, Japan.
FAU - Mizuno, Koh
AU  - Mizuno K
AD  - Faculty of Education, Tohoku Fukushi University, Miyagi, Japan.
AD  - Space Biomedical Research Group, Japan Aerospace Exploration Agency, Tokyo, 
      Japan.
FAU - Ohshima, Hiroshi
AU  - Ohshima H
AD  - Space Biomedical Research Group, Japan Aerospace Exploration Agency, Tokyo, 
      Japan.
FAU - Furukawa, Satoshi
AU  - Furukawa S
AD  - Space Biomedical Research Group, Japan Aerospace Exploration Agency, Tokyo, 
      Japan.
FAU - Mukai, Chiaki
AU  - Mukai C
AD  - Space Biomedical Research Group, Japan Aerospace Exploration Agency, Tokyo, 
      Japan.
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20180710
PL  - England
TA  - Sci Rep
JT  - Scientific reports
JID - 101563288
SB  - IM
MH  - Adaptation, Psychological/physiology
MH  - Astronauts/*psychology
MH  - Brain/*physiology
MH  - Circadian Rhythm/*physiology
MH  - Consciousness/physiology
MH  - Female
MH  - Heart Rate/*physiology
MH  - Humans
MH  - Male
MH  - Middle Aged
MH  - *Space Flight
MH  - Time Factors
MH  - *Weightlessness
PMC - PMC6039530
COIS- The authors declare no competing interests.
EDAT- 2018/07/12 06:00
MHDA- 2019/11/26 06:00
PMCR- 2018/07/10
CRDT- 2018/07/12 06:00
PHST- 2018/04/12 00:00 [received]
PHST- 2018/06/28 00:00 [accepted]
PHST- 2018/07/12 06:00 [entrez]
PHST- 2018/07/12 06:00 [pubmed]
PHST- 2019/11/26 06:00 [medline]
PHST- 2018/07/10 00:00 [pmc-release]
AID - 10.1038/s41598-018-28740-z [pii]
AID - 28740 [pii]
AID - 10.1038/s41598-018-28740-z [doi]
PST - epublish
SO  - Sci Rep. 2018 Jul 10;8(1):10381. doi: 10.1038/s41598-018-28740-z.