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Wavelet cross-correlation (WCC) is used to analyse the relationship between low-frequency oscillations in near-infrared spectroscopy (NIRS) measured cerebral oxyhaemoglobin (O(2)Hb) 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 O(2)Hb 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.

Original publication

DOI

10.1088/0967-3334/28/2/005

Type

Journal article

Journal

Physiological measurement

Publication Date

02/2007

Volume

28

Pages

161 - 173

Addresses

Department of Engineering Science, University of Oxford, Oxford, UK. abr@robots.ox.ac.uk

Keywords

Humans, Autonomic Nervous System Diseases, Oxyhemoglobins, Spectroscopy, Near-Infrared, Plethysmography, Tilt-Table Test, Data Interpretation, Statistical, Brain Chemistry, Homeostasis, Blood Pressure, Supine Position, Algorithms, Adult, Aged, Middle Aged, Female, Male