title: Hyperthermia-induced disruption of functional connectivity in the human brain network.
abstract: BACKGROUND
  Passive hyperthermia is a potential risk factor to human cognitive performance and work behavior in many extreme work environments. Previous studies have demonstrated significant effects of passive hyperthermia on human cognitive performance and work behavior. However, there is a lack of a clear understanding of the exact affected brain regions and inter-regional connectivities.
  
  
  RESULTS
  We simulated 1 hour environmental heat exposure to thirty-six participants under two environmental temperature conditions (25 °C and 50 °C), and collected resting-state functional brain activity. The functional connectivities with a preselected region of interest (ROI) in the posterior cingulate cortex and precuneus (PCC/PCu), furthermore, inter-regional connectivities throughout the entire brain using a prior Anatomical Automatic Labeling (AAL) atlas were calculated. We identified decreased correlations of a set of regions with the PCC/PCu, including the medial orbitofrontal cortex (mOFC) and bilateral medial temporal cortex, as well as increased correlations with the partial orbitofrontal cortex particularly in the bilateral orbital superior frontal gyrus. Compared with the normal control (NC) group, the hyperthermia (HT) group showed 65 disturbed functional connectivities with 50 of them being decreased and 15 of them being increased. While the decreased correlations mainly involved with the mOFC, temporal lobe and occipital lobe, increased correlations were mainly located within the limbic system. In consideration of physiological system changes, we explored the correlations of the number of significantly altered inter-regional connectivities with differential rectal temperatures and weight loss, but failed to obtain significant correlations. More importantly, during the attention network test (ANT) we found that the number of significantly altered functional connectivities was positively correlated with an increase in executive control reaction time.
  
  
  CONCLUSIONS
  We first identified the hyperthermia-induced altered functional connectivity patterns. The changes in the functional connectivity network might be a possible explanation for the cognitive performance and work behavior alteration.
authors.affiliation: Department of Medical Imaging, Jinan Military General Hospital, Jinan, Shandong, People's Republic of China.
authors.forename: Gang
authors.initials: G
authors.lastname: Sun
authors.forename: Shaowen
authors.initials: S
authors.lastname: Qian
authors.forename: Qingjun
authors.initials: Q
authors.lastname: Jiang
authors.forename: Kai
authors.initials: K
authors.lastname: Liu
authors.forename: Bo
authors.initials: B
authors.lastname: Li
authors.forename: Min
authors.initials: M
authors.lastname: Li
authors.forename: Lun
authors.initials: L
authors.lastname: Zhao
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Zhou
authors.forename: Karen M
authors.initials: KM
authors.lastname: von Deneen
authors.forename: Yijun
authors.initials: Y
authors.lastname: Liu
mesh_terms: D000293:Adolescent; D001288:Attention; D001831:Body Temperature; D001835:Body Weight; D001921:Brain / Q000503:physiopathology*; D005260:Female; D005334:Fever / Q000503:physiopathology*; D059907:Functional Neuroimaging; D006179:Gyrus Cinguli / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009415:Nerve Net / Q000503:physiopathology*; D010296:Parietal Lobe / Q000503:physiopathology; D055815:Young Adult