Newer concepts in pain mechanisms

This review addresses investigations of how nociceptive information is processed in the brain, and the role of nerve growth factor in the neurobiology of nociception. The brain studies probe the neuronal matrix concept of how pain is perceived, and are based on brain imaging techniques, positron emission tomography (PET), and functional magnetic resonance imaging (fMRI). The critical role of nerve growth factor in the embryogenesis of primary afferent cell bodies (nociceptors, small diameter axons, dorsal root ganglia and their terminals in the spinal cord) and in inflammatory processes in adults are reviewed. Neuroimaging data support the neuronal matrix concept, and the potential therapeutic opportunities offered by pharmacologically targeting various aspects of nerve growth factor and its interaction with its receptor are clear.