The validity of the face-selective ERP N170 component during simultaneous recording with functional MRI.

Despite the wide interest in the neural mechanisms of face processing and numerous event-related potential (ERP) and functional MRI (fMRI) studies of face-selective neural responses, no study, to date, has collected these two measures simultaneously. The main reason for the absence of such an investigation is that MRI data acquisition generates major artifacts, which completely conceals the EEG signal. Recently, artifact removal algorithms have been developed. Our goal was to examine the validity of the face-selective ERP component N170 and its functional effects such as category selectivity and hemispherical laterality, when recorded simultaneously with functional MRI. In our experiment, half of the scans were collected during fMRI acquisition and half without fMRI acquisition. The validity of the N170 was then measured for its amplitude, latency, face selectivity (the difference between the amplitude to faces and objects), laterality (the difference between the amplitude to faces over the right and the left hemispheres) and the laterality of the face selectivity effect, by correlating these measures across subjects between data collected without fMRI and with fMRI data acquisition, after applying artifact removal procedures. We found high validity coefficients for all N170 measures. Furthermore, ERP data collected outside the scanner on a different day were highly correlated with data collected during MR acquisition for the N170 amplitude, latency, and selectivity index but moderate for laterality indices. Our study demonstrates that face-selective ERP effects are preserved in simultaneous recording with fMRI. These findings will hopefully encourage researchers to combine the two complementary neuroimaging techniques in future research.