Correlation of fluctuations in simultaneously recorded VEP and BOLD fMRI

Introduction Studies comparing visual evoked potentials (VEPs) and BOLD signals have found a positive correlation between the VEP amplitude and the magnitude and extent of the BOLD signal [1, 2], but some VEP components are better related to the BOLD signal than others. The strongest spatial correlation have been found between the source location of the N1 peak* and the location of the BOLD signal [3]. While previous studies with simultaneously recorded VEP-fMRI have only compared the correlation between the grand mean VEP and the averaged BOLD signal, there is growing interest in correlating simultaneously acquired VEP and BOLD fMRI data. In this case, however, the N1 peak becomes difficult to identify due to excessive noise amplification of the EEG inside the MR scanner. Therefore, we examined alternative ways to measure neuronal activation in simultansouly recorded VEP-fMRI.