Detection of synchronized oscillations in the electroencephalogram: An evaluation of methodsNick Yeung, Rafal Bogacz, Clay B. Holroyd, Jonathan D. Cohen, Detection of synchronized oscillations in the electroencephalogram: An evaluation of methods. Psychophysiology, 41, pp. 822–832. November 2004. PDF, 1084 Kbytes.
The signal averaging approach typically used in ERP research assumes that peaks in ERP waveforms reflect neural activity that is uncorrelated with activity in the ongoing EEG. However, this assumption has been challenged by research suggesting that ERP peaks reflect event-related synchronization of ongoing EEG oscillations. In this study, we investigated the validity of a set of methods that have been used to demonstrate that particular ERP peaks result from synchronized EEG oscillations. We simulated epochs of EEG data by superimposing phasic peaks on noise characterized by the power spectrum of the EEG. When applied to the simulated data, the methods in question produced results that have previously been interpreted as evidence of synchronized oscillations, even though no such synchrony was present. These findings suggest that proposed analysis methods may not effectively disambiguate competing views of ERP generation.