Imaging modalities for pain

Abstract

Information transfer in the brain takes place by electrical conduction along axons and chemical interaction between neurons. Functional brain imaging is a general term for techniques measuring correlates of neuronal activity. The techniques used most often are functional magnetic resonance imaging (fMRI), positron emission tomography (PET), single photon emission computed tomography (SPECT), electroencephalography (EEG), magnetoencephalography (MEG) and MR spectroscopy (Apkarian et al., 2005). The outputs measured are cerebral blood flow (fMRI/PET), electrophysiology (EEG/MEG), neurochemistry (PET/SPECT) and relative chemical concentrations (MR spectroscopy) (Apkarian et al., 2005). In the context of pain research, fMRI is the most commonly used today; not only for activation studies, but for identifying interactions and connectivities between brain regions during the modulation of pain. PET is decreasing in use for pain activation studies, but is becoming increasingly popular for detecting the neurochemistry of neuronal communication. EEG and MEG are popular mainly for detecting temporal sequences. Although there are a variety of important imaging techniques; in this chapter we will focus on three of the main functional imaging methods used to study pain: MEG, fMRI, and PET.