Functional Magnetic Resonance Imaging (fMRI)

Funcional magnetic resonance imaging (fMRI) MR MachinefMRI is a non-invasive technique to study neuronal activation, based on the difference in magnetic properties of oxygenated versus de-oxygenated blood supply to the brain. fMRI is thus an indirect measure of neuronal activity by measuring regional changes in blood supply with the assumption of a positive relationship between neuronal activity and brain metabolism. The contrast in signal intensity between oxygenated and de-oxygenated blood is labelled the Blood-Oxygenation-Level-Dependent (BOLD) contrast. fMRI brain activation studies  were first reported in  1991 - 1992 (Bellevieau et al. Science, 1991; Bandettini et al., Magn Res Med, 1992) using simple sensory tasks, and has ever since grown in popularity and importance for the understanding of the neuronal basis for cognitive and affective behaviour. Recent years have also seen the application of fMRI for clinical purposes, mainly in psychiatry, neurology and neurosurgery, but also in radiology. An fMRI investigation requires elaborate post-acquisition processing of the images, where the end product typically is color-coded regions added to an anatomical template of the brain.


Brain activation
The animation shows an example of BOLD fMRI activation in the posterior temporal lobe, with a left-sided asymmetry, to presentations of simple speech sounds.

 The first BOLD fMRI studies in Norway were done at the Haukeland University Hospital by members of the Bergen fMRI Group in October 1993, and the first publication was published in 1995 (Lundervold et al.  1995). Today the Bergen fMRI Group has about 30 members and are conducting both research and clinical studies, also including related measures like, voxel-based morphometry (VBM), diffusion tensor imaging (DTI), MR spectroscopy (MRS), simultaneous EEG-fMRI recordings, and Arterial Spin Labeling (ASL). The group also has a state-of-the-art laboratory for trans-cranial magnetic stimulation (TMS) studies.