Abstract

The analysis of synchronization, particularly phase locking, is being increasingly used in neuroscience to explore coordinated brain activity. The application of this methodology to magnetoencephalographic (MEG) and electroencephalographic (EEG) recordings would seem promising because these two recording techniques are not invasive and have great temporal resolution. However, current methods of synchronization analysis applied directly to raw MEG/EEG data may produce distorted results. In this work we introduce a model of brain activity based on random current dipoles that reproduces the main characteristics observed in measurements of real data synchronization, even when no synchronized activity is taking place among the sources. In particular we describe the effect of field superposition alone when secondary currents are excluded. It is also shown that the enhanced local synchronization, previously described in some studies of epileptic seizures, may result from the activity of only a few unsynchronized sources. We suggest three lines of research for further development and improvement to obtain more precise physiological interpretations of the synchronization analysis.

Key words: Phase synchronization, Magnetoencephalography, Epilepsy