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Int J Hyperthermia. 2018 Nov;34(7):1010-1019. doi: 10.1080/02656736.2017.1392046. Epub 2017 Nov 1.

The effects of head-cooling on brain function during passive hyperthermia: an fMRI study.

Author information

1
a Graduate School, Jinzhou Medical University , Jinzhou , China.
2
b Department of Medical Imaging , Jinan Military General Hospital , Jinan , China.
3
c Institute of Postgraduates, The Second Military Medical University , Shanghai , China.
4
d Center for MR Research, and Department of Radiology , University of Illinois at Chicago , Chicago , IL , USA.

Abstract

PURPOSE:

To investigate the effect of head-cooling on resting-state spontaneous brain activity during passive hyperthermia.

METHODS:

An environmental heat exposure was simulated on 16 healthy men under a normal control condition (NC) at 25 °C and two hot conditions at 50 °C with hyperthermia with head-cooling condition (HHC) and without hyperthermia condition (HOT) keeping the head cool, respectively. Resting-state functional MRI (fMRI) data were acquired under each condition and the values of amplitude low frequency fluctuations (ALFF) and z functional connectivity (zFC) were computed to examine regional activity and functional integration, respectively. Pearson's correlation analysis between the ALFF value and subjective sensations scores were performed.

RESULTS:

Brain regions with significant ALFF differences among the three conditions were found primarily in the right medial prefrontal cortex/anterior cingulate cortex (MPFC/ACC), bilateral posterior cingulate cortex/precuneus (PCC/PCu), and right fusiform gyrus. Compared to the NC or HOT condition, the HHC condition exhibited significantly increased ALFF in the bilateral PCC/PCu and decreased ALFF in the right fusiform gyrus. However, ALFF of the right MPFC/ACC showed no significant difference between the NC and HHC conditions. Positive FC between the right MPFC/ACC and bilateral PCC/PCu was significantly increased in HHC condition with respect to HOT condition. Negative FC between the right fusiform gyrus and the right MPFC/ACC, bilateral PCC/PCu was observed with a decreasing trend from the HHC condition to the HOT condition. Moreover, head-cooling also improved thermal comfort during passive hyperthermia.

CONCLUSIONS:

Head-cooling could substantially reduce the negative effect of hyperthermia on human brain activity as well as thermal sensation.

KEYWORDS:

Hyperthermia; fMRI; head-cooling; thermal sensations

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