title: Wavelet coherence analysis of prefrontal oxygenation signals in elderly subjects with hypertension.
abstract: This study aims to assess the prefrontal functional connectivity in elderly subjects with hypertension during the resting state using wavelet coherence analysis of changes in prefrontal tissue oxyhaemoglobin concentrations (Δ[HbO2]) signals measured by near-infrared spectroscopy (NIRS). Continuous recordings of NIRS signals were obtained from the left and right prefrontal lobes in 24 elderly subjects with hypertension (age: 70.7 ± 8.4 years) and 26 elderly normotensive subjects (age: 70.6 ± 7.9 years) during the resting state. The coherence between the left and right prefrontal oscillations in four frequency intervals (I, 0.4 Hz to 2 Hz; II, 0.15 Hz to 0.4 Hz; III, 0.05 Hz to 0.15 Hz; and IV, 0.02 Hz to 0.05 Hz) was analyzed using wavelet coherence method. The Δ[HbO2] oscillations showed significant wavelet coherence (WCO) in intervals I and III, and significant wavelet phase coherence (WPCO) in intervals from I to IV. Remarkably, in elderly subjects with hypertension, the WCO and WPCO in interval III were significantly lower in the left and right prefrontal regions than in healthy elderly subjects (p = 0.014 for WCO, p = 0.007 for WPCO). The lower coherence in interval III indicates a decreased synchronization of neural control in the left and right prefrontal regions in elderly subjects with hypertension. This might suggest a weakened brain functional connectivity in the elderly subjects with hypertension.
authors.affiliation: Key Laboratory of High Efficiency and Clean Mechanical Manufacture, School of Mechanical Engineering, Shandong University, Jinan 250061, People's Republic of China.
authors.forename: Zengyong
authors.initials: Z
authors.lastname: Li
authors.forename: Ming
authors.initials: M
authors.lastname: Zhang
authors.forename: Ruofei
authors.initials: R
authors.lastname: Cui
authors.forename: Qing
authors.initials: Q
authors.lastname: Xin
authors.forename: Lu
authors.initials: L
authors.lastname: Liqian
authors.forename: Weiei
authors.initials: W
authors.lastname: Zhou
authors.forename: Qingyu
authors.initials: Q
authors.lastname: Han
authors.forename: Yuanjin
authors.initials: Y
authors.lastname: Gao
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D006973:Hypertension / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D009415:Nerve Net / Q000378:metabolism / Q000503:physiopathology; D010100:Oxygen / Q000378:metabolism*; D010108:Oxyhemoglobins / Q000378:metabolism; D017397:Prefrontal Cortex / Q000378:metabolism* / Q000503:physiopathology; D019265:Spectroscopy, Near-Infrared; D058067:Wavelet Analysis
chemical_list: D010108:Oxyhemoglobins; D010100:Oxygen