Time-frequency analysis of spontaneous pupillary oscillation signals using the Hilbert-Huang transform

The intrinsic properties of the spontaneous pupillary oscillation signals were characterized under the HHT scheme. The obtained results showed that SPO waves exhibit local and intermittent variations through the time span. From the numerical parameters that were obtained, we could observe that there is a wide inter-subject variation in the contribution of the intrinsic time-frequency parameters from each yielding mode to the total signal content.