Rowley A.B.Payne S.J.Tachtsidis I.Ebden M.J.Whiteley J.P.Gavaghan D.J.Tarassenko L.Smith M.Elwell C.E.Delpy D.T.STEPHEN JOHN PAYNE2022-05-242022-05-242007https://www.scopus.com/inward/record.uri?eid=2-s2.0-33947722691&doi=10.1088%2f0967-3334%2f28%2f2%2f005&partnerID=40&md5=f7635a62b9194809103b4704d024738dhttps://scholars.lib.ntu.edu.tw/handle/123456789/611857Wavelet cross-correlation (WCC) is used to analyse the relationship between low-frequency oscillations in near-infrared spectroscopy (NIRS) measured cerebral oxyhaemoglobin (O2Hb) and mean arterial blood pressure (MAP) in patients suffering from autonomic failure and age-matched controls. Statistically significant differences are found in the wavelet scale of maximum cross-correlation upon posture change in patients, but not in controls. We propose that WCC analysis of the relationship between O2Hb and MAP provides a useful method of investigating the dynamics of cerebral autoregulation using the spontaneous low-frequency oscillations that are typically observed in both variables without having to make the assumption of stationarity of the time series. It is suggested that for a short-duration clinical test previous transfer-function-based approaches to analyse this relationship may suffer due to the inherent nonstationarity of low-frequency oscillations that are observed in the resting brain. ? 2007 IOP Publishing Ltd.Blood pressureInfrared devicesTime series analysisWavelet analysisArterial blood pressureCerebral circulationFrequency oscillationsLower frequenciesMean arterial blood pressuresPosture changeSpontaneous oscillationsSympathetic stimulationTime-frequency AnalysisWavelet cross-correlationNear infrared spectroscopyadultagedarticleautonomic dysfunctionautoregulationbody posturebrain cortexcontrolled studycorrelation analysisdynamicshemoglobin determinationhumanmean arterial pressurenear infrared spectroscopyoscillationpriority journalstatistical significancewaveformalgorithmautonomic neuropathyblood pressurebrain levelfemalehomeostasismalemetabolismmiddle agedpathophysiologyphysiologyplethysmographystatistical analysissupine positiontilt table testoxyhemoglobinAdultAgedAlgorithmsAutonomic Nervous System DiseasesBlood PressureBrain ChemistryData Interpretation, StatisticalFemaleHomeostasisHumansMaleMiddle AgedOxyhemoglobinsPlethysmographySpectroscopy, Near-InfraredSupine PositionTilt-Table Test[SDGs]SDG3journal article10.1088/0967-3334/28/2/0052-s2.0-33947722691