title: Phase synchronization measurements using electroencephalographic recordings: what can we really say about neuronal synchrony?
abstract: Phase synchrony analysis is a relatively new concept that is being increasingly used on neurophysiological data obtained through different methodologies. It is currently believed that phase synchrony is an important signature of information binding between distant sites of the brain, especially during cognitive tasks. Electroencephalographic (EEG) recordings are the most widely used recording technique for recording brain signals and assessing phase synchrony patterns. In this study, we address the suitability of phase synchrony analysis in EEG recordings. Using geometrical arguments and numerical examples, employing EEG and magnetoencephalographic data, we show that the presence of a common reference signal in the case of EEG recordings results in a distortion of the synchrony values observed, in that the amplitudes of the signals influence the synchrony measured, and in general destroys the intended physical interpretation of phase synchrony.
authors.affiliation: Abdus Salam ICTP, Strada Costiera 11, 34100, Miaramare, Trieste, Italy.
authors.forename: Ramón
authors.initials: R
authors.lastname: Guevara
authors.forename: José Luis Pérez
authors.initials: JL
authors.lastname: Velazquez
authors.forename: Vera
authors.initials: V
authors.lastname: Nenadovic
authors.forename: Richard
authors.initials: R
authors.lastname: Wennberg
authors.forename: Goran
authors.initials: G
authors.lastname: Senjanovic
authors.forename: Luís Garcia
authors.initials: LG
authors.lastname: Dominguez
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000465:Algorithms; D000818:Animals; D001921:Brain / Q000502:physiology*; D003344:Cortical Synchronization / Q000379:methods / Q000639:trends; D004569:Electroencephalography / Q000379:methods* / Q000639:trends; D004594:Electrophysiology / Q000379:methods; D005071:Evoked Potentials / Q000502:physiology; D006801:Humans; D015225:Magnetoencephalography / Q000379:methods; D009474:Neurons / Q000502:physiology*; D012815:Signal Processing, Computer-Assisted