[Neural networks and pain processing. New insights from imaging techniques]

Imaging techniques with high spatial and temporal resolution (PET,fMRI, MEG) provide detailed information about the brains' processing of pain. Structures detected by these techniques are not understood as pain centers but as nodal points of a dynamic network which is influenced by physiological and psychological input. Imaging techniques can be used for the investigation of different pain components. The neuronal network that encodes sensory-discriminative information consists of the primary and secondary somatosensory cortex which receive input from lateral thalamic nuclei. Information for the affective pain component reach the anterior cingulate cortex, insula and prefrontal cortex via medial thalamic nuclei. Until now only little is known about cortical structures mediating the cognitive pain component. In chronic pain the cortical and subcortical processing of nociceptive input is presumably modified. Reorganization in the primary somatosensory cortex is presented as an example of neuronal plasticity induced by chronic pain.