Brain Topography

, Volume 23, Issue 3, pp 233–242 | Cite as

A Method to Determine the Presence of Averaged Event-Related Fields Using Randomization Tests

  • Thomas Koenig
  • Lester Melie-García
Original Paper


We present a simple and effective method to test whether an event consistently activates a set of brain electric sources across repeated measurements of event-related scalp field data. These repeated measurements can be single trials, single subject ERPs, or ERPs from different studies. The method considers all sensors simultaneously, but can be applied separately to each time frame or frequency band of the data. This allows limiting the analysis to time periods and frequency bands where there is positive evidence of a consistent relation between the event and some brain electric sources. The test may therefore avoid false conclusions about the data resulting from an inadequate selection of the analysis window and bandpass filter, and permit the exploration of alternate hypotheses when group/condition differences are observed in evoked field data. The test will be called topographic consistency test (TCT). The statistical inference is based on simple randomization techniques. Apart form the methodological introduction, the paper contains a series of simulations testing the statistical power of the method as function of number of sensors and observations, a sample analysis of EEG potentials related to self-initiated finger movements, and Matlab source code to facilitate the implementation. Furthermore a series of measures to control for multiple testing are introduced and applied to the sample data.


Evoked potentials Randomization Global Field Power Averaging Signal-to-noise ratio 



The authors wish to thank the two reviewers for their constructive and fast responses to the initial version of the manuscript.


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Copyright information

© Springer Science+Business Media, LLC 2010

Authors and Affiliations

  1. 1.Department of Psychiatric NeurophysiologyUniversity Hospital of Psychiatry, University of BernBernSwitzerland
  2. 2.Neuroinformatics DepartmentCuban Neuroscience CenterHavanaCuba

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