Singular Spectrum Analysis of pupillometry data. Identification of the sympathetic and parasympathetic activity

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review


  • Ana Franco
  • Carlos Marques Neves
  • Carla Quintao
  • Ricardo Vigario
  • Pedro Vieira

Research units

  • University of Lisbon
  • NOVA University of Lisbon


The pupil shows a fast dynamical adaptation to external light changes, in order to potentiate visual perception. It contracts in high luminosity environments, so as to limit the quantity of photons that reach the retina (miosis) and dilates in environments with little luminosity, thus increasing the number of photons in the retina (mydriasis). Hence, the pupil acts as a normalizer of the quantity of light that enters the optical system. These pupillary movements are controlled by the action of smooth muscles, which are associated with the sympathetic (SNS) and parasympathetic autonomous nervous systems (PsNS). Therefore, the study of the pupillary dynamics can lead to inferences on the functioning of those two antagonist systems and their involvement in pupillary control. In addition, our study may prove clinically helpful in determining a patient's level of consciousness, as well as identifying certain diseases, such as sleep disorders, photophobia, schizophrenia, Adie syndrome, Alzheimer's and Parkinson's disease. With a clear goal in its clinical applications, we focus our research in the identification of the frequency intervals pertaining to the action of the autonomous nervous system, as well as their individual sympathetic and parasympathetic roles. We analyze high-resolution, non-invasive pupillometric signals, both in a basal condition and as a response to visual flashes or to the application of a cold stimulus. We use Singular Spectrum Analysis (SSA) to identify the frequencies of interest related to the actions of the SNS and PsNS. In addition, and as a complementary means of frequency analysis, we also use the more classical wavelets analysis. We find out that SSA is an ideal tool for the identification of the desired frequencies in stake. The agreement between the outcomes of both analyses supports our conclusions regarding the autonomous nervous system. (C) 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (


Original languageEnglish
Title of host publicationConference on Electronics, Telecommunications and Computers – CETC 2013
EditorsA Fantoni, AJ Ferreira
Publication statusPublished - 2014
MoE publication typeA4 Article in a conference publication
EventConference on Electronics, Telecommunications and Computers - Lisbon, Portugal
Duration: 5 Dec 20136 Dec 2013
Conference number: 2

Publication series

NameProcedia Technology
ISSN (Print)2212-0173


ConferenceConference on Electronics, Telecommunications and Computers
Abbreviated titleCETC

    Research areas

  • pupil, pupilometry, singular spectrum analysis, frequency, sympathetic nervous system, parasympathetic nervous system, wavelets, PRINCIPAL DYNAMIC-MODES, HEART-RATE-VARIABILITY, NERVE ACTIVITY

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