Low-dissipation optimization of the prefrontal cortex in the -12° head-down tilt position: A functional near-infrared spectroscopy study

Tingting Lun; Dexin Wang; Li Li; Junliang Zhou; Yunxuan Zhao; Yuecai Chen; Xuntao Yin; Shanxing Ou; Jin Yu; Rong Song

doi:10.3389/fpsyg.2022.1051256

Low-dissipation optimization of the prefrontal cortex in the -12° head-down tilt position: A functional near-infrared spectroscopy study

Front Psychol. 2022 Dec 21:13:1051256. doi: 10.3389/fpsyg.2022.1051256. eCollection 2022.

Authors

Tingting Lun¹, Dexin Wang¹, Li Li², Junliang Zhou³, Yunxuan Zhao¹, Yuecai Chen¹, Xuntao Yin⁴, Shanxing Ou⁵, Jin Yu¹, Rong Song⁶

Affiliations

¹ Clinical Medical College of Acupuncture, Moxibustion and Rehabilitation, Guangzhou University of Chinese Medicine, Guangzhou, China.
² College of TCM health care, Guangdong Food and Drug Vocational College, Guangzhou, China.
³ Department of Traditional Chinese Medicine, Nanhai District Maternal and Child Health Hospital, Foshan, China.
⁴ Department of Radiology, Guangzhou women and children's Medical Center, Guangzhou Medical University, Guangzhou, China.
⁵ Department of Radiology, Southern Theater Command Hospital of PLA, Guangzhou, China.
⁶ Guangdong Provincial Key Laboratory of Sensor Technology and Biomedical Instrument, School of Biomedical Engineering, Sun Yat-sen University, Guangzhou, China.

Abstract

Introduction: Our present study set out to investigate the instant state of the prefrontal cortex (PFC) in healthy subjects before and after placement in the -12°head-down tilt (HDT) position in order to explore the mechanism behind the low-dissipation optimization state of the PFC.

Methods: 40 young, right-handed healthy subjects (male: female = 20: 20) were enrolled in this study. Three resting state positions, 0°initial position, -12°HDT position, and 0°rest position were sequentially tested, each for 10 minutes. A continuous-wave functional near-infrared spectroscopy (fNIRS) instrument was used to assess the resting state hemodynamic data of the PFC. After preprocessing the hemodynamics data, we evaluated changes in resting-state functional connectivity (rsFC) level and beta values of PFC. The subjective visual analogue scale (VAS) was applied before and after the experiment. The presence of sleep changes or adverse reactions were also recorded.

Results: Pairwise comparisons of the concentrations of oxyhemoglobin (HbO), deoxyhemoglobin (HbR), and hemoglobin (HbT) revealed significant differences in the aforementioned positions. Specifically, the average rsFC of PFC showed a gradual increase throughout the whole process. In addition, based on graph theory, the topological properties of brain network, such as small-world network and nodal degree centrality were analyzed. The results show that global efficiency and small-world sigma (σ) value were differences between 0°initial and 0°rest.

Discussion: In this study, placement in the -12°HDT had a significant effect on PFC function, mainly manifested as self-inhibition, decreased concentration of HbO in the PFC, and improved rsFC, which may provide ideas to the understanding and explanation of neurological diseases.

Keywords: functional near infrared spectroscopy; graph theory; head down tilt; low dissipation optimization state; prefrontal cortex; resting-state functional connectivity.