Perception of postural instability as revealed by Morlet wavelet transform in EEG

Our principal finding from this study is that there were changes at the level of brain electrical activity (EEG), in time-frequency domain, during states of perceptual detection of postural instability of the Virtual Person. The Morlet wavelet transform was applied to examine phase-locking transition within 10-40 Hz frequencies range as a function of change in the focused attention during perceptual tasks aimed to detect non-stable postural dynamics. It was found that high energy 40 Hz time-frequency cluster at 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 the time-frequency analysis as an invaluable tool for detection, estimation and tracking the event-related EEG frequency distributions.