Non-linear EEG synchronization during observation and execution of simple and complex sequential finger movements.

The main aim of this study was to examine the temporal aspects of neuronal changes during the observation and execution of simple and complex tasks to gain a greater understanding of the mirror neuron system's involvement in complex motor tasks. Eleven right-handed subjects observed simple and complex finger movement sequences. Electroencephalograms were recorded from 19 electrodes. Activity was considered in four frequency bands (8-10, 10-13, 13-20, and 20-30 Hz) using a new measure, synchronization likelihood. The results show that motor tasks of different levels of complexity did not have a significant influence on cortical synchronization. The results also provide additional indirect evidence for mirror neuron activity associated with intransitive tasks. Data are discussed in the light of recent findings from the cognitive and behavioral neuroscience literature.