Repetition suppression and effects of familiarity on blood oxygenation level dependent signal and gamma-band activity.

We used an identical repetition priming paradigm infunctional MRI (fMRI) and magnetoencephalography(MEG) to investigate brain networks modulated bystimulus repetition and familiarity. In particular, pictures offamiliar or unfamiliar objects were presented sequentially,with stimulus repetitions occurring within few trials. Theresults of both studies indicated close agreement betweenthe pattern found in fMRI-BOLD (blood oxygenation leveldependent) responses and in source localizations ofinduced gamma-band activity derived from MEG. In bothstudies, the brain regions that were significantly associatedwith repetition suppression in response to familiar visualobjects encompassed bilaterally the medial and lateraloccipital cortex, inferior occipitotemporal regions includingthe left fusiform cortex, as well as parietal areas.Modulations by stimulus familiarity occurred mainly withinthis network. Overall, we found noticeablecorrespondences between the results of fMRI-BOLDsignals and MEG gamma-band activity, suggesting thatboth methods can be used in analogous ways to studythe neural basis of repetition priming and objectrecognition. NeuroReport 23:757–761