The perception of postural instability as revealed by Morlet wavelet transform in EEG

Our principal finding from this study is that there are changes at the level of brain electrical activity (EEG), in the time-frequency domain, during states of perceptual detection of postural instability of the virtual person. The Morlet wavelet transform was applied to examine the phase-locking transition within the 10-40 Hz frequency range as a function of change in the focused attention during perceptual tasks aimed to detect non-stable postural dynamics. It was found that the high energy 40 Hz time-frequency cluster at the fronto-central area was preceded by 20 Hz signal activity and followed by a 30 Hz signal cluster when subjects detect non-stable postures. This fortifies the use of time-frequency analysis as an invaluable tool for the detection, estimation and tracking of event-related EEG frequency distributions