RT Journal Article
SR Electronic
T1 A New Method to Detect Event-Related Potentials Based on Pearson’s Correlation
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 022046
DO 10.1101/022046
A1 William Giroldini
A1 Luciano Pederzoli
A1 Marco Bilucaglia
A1 Simone Melloni
A1 Patrizio Tressoldi
YR 2015
UL http://biorxiv.org/content/early/2015/10/09/022046.abstract
AB Event-Related Potentials (ERPs) are widely used in Brain-Computer Interface applications and in neuroscience.Normal EEG activity is rich in background noise and therefore, in order to detect ERPs, it is usually necessary to take the average from multiple trials to reduce the effects of this noise.The noise produced by EEG activity itself is not correlated with the ERP waveform and so, by calculating the average, the noise is decreased by a factor inversely proportional to the square root of N, where N is the number of averaged epochs.This is the easiest strategy currently used to detect ERPs, which is based on calculating the average of each ERP’s waveform, these waveforms being time-and phase-locked.In this paper a new method called GW6 is proposed, which calculates the ERP using a mathematical method based only on Pearson's Correlation.This results in a graph with the same time resolution as the classical ERP and which contains only positive peaks representing the increase -in consonance to the stimuli - in EEG signal correlation over all channels.This new method is also useful for selectively identifying and highlighting any hidden components of the ERP response that are not phase-locked, and that are usually hidden in the standard and simple method based on the averaging of all the epochs.These hidden components seem to be caused by variations (between each successive stimulus) of the ERP's inherent phase latency period (jitter), although the same stimulus across all EEG channels produces a reasonably constant phase.For this reason, this new method could be very helpful to investigate these hidden components of the ERP response and to develop applications for scientific and medical purposes.Moreover, this new method is more resistant to EEG artifacts than the standard calculations of the average.The method we are proposing can be directly used in the form of a process written in the well known Matlab programming language and can be easily and quickly written in any other software language.