Visualization of significant ERD/ERS patterns in multichannel EEG and ECoG data

Objectives: Analysis of event-related desynchronization (ERD) and event-related synchronization (ERS) often requires the investigation of diverse frequency bands. Such analysis can be difficult, especially when using multichannel data. Therefore, an effective method for the visualization of event-related changes in oscillatory brain activity is required. Methods: A bootstrap-based method is presented which gives time–frequency maps showing only significant changes of ERD or ERS in predetermined frequency bands. Results: Examples from an electroencephalographic study and an electrocorticographic study are shown. The results demonstrate how easily reactive channels and their spatio-temporal and frequency-specific characteristics can be identified by means of this method. Conclusions: The proposed method is a simple but effective way to visualize significant ERD/ERS patterns.