Exploring brain function with magnetic resonance imaging

Since its invention in the early 1990s, functional magnetic resonance imagi ng (fMRI) has rapidly assumed a leading role among the techniques used to l ocalize brain activity. The spatial and temporal resolution provided by sta te-of-the-art MR technology and its non-invasive character, which allows mu ltiple studies of the same subject, are some of the main advantages of fMRI over the other functional neuroimaging modalities that are based on change s in blood flow and cortical metabolism. This paper describes the basic pri nciples and methodology of fMRI and some aspects of its application to func tional activation studies. Attention is focused on the physiology of the bl ood oxygenation level-dependent (BOLD) contrast mechanism and on the acquis ition of functional time-series with echo planar imaging (EPI). We also pro vide an introduction to the current strategies for the correction of signal artefacts and other image processing techniques. In order to convey an ide a of the numerous applications of fMRI, we will review some of the recent r esults in the fields of cognitive and sensorimotor psychology and physiolog y. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.