Localizing the neonatal and fetal spontaneous brain activity by Hilbert phase analysis.

We propose a novel method to characterize the spontaneous brain signals using Hilbert phases. The Hilbert phase of a signal exhibits phase slips when the magnitude of the successive phase difference exceeds pi. To this end we use standard deviation (sigmaDeltatau) of the time (Deltatau) between successive phase slips to characterize the signals. We demonstrate the application of this approach to neonatal and fetal magnetoencephalographic signals recorded using a 151-sensor array to identify the sensors containing the neonatal and fetal brain signals. To this end we propose a spatial filter using sigma(Deltatau) as weights to reconstruct the brain signals.