The major aim of this research line is to analyze the brain activity in chronic pain patients using functional magnetic resonance imaging (fMRI) and EEG. The underlying hypothesis is that chronic pain is characterized by plastic changes of the nervous system. Our experimental design pursues to demonstrate the existence of abnormal pattern in the brain processing of somatic information in chronic pain patients. In addition, we are interested on the influence of cognitive and affective factors on brain plastic changes. Three patients groups with similar sociodemographic, but different clinical characteristics are examined: fibromyalgia, complex regional pain syndrome and rheumatoid arthritis. Brain activity is recorded during nociceptive and non-nociceptive stimulation using fMRI. In addition, psychological characteristics of pain, neuropsychological functioning and pain thresholds are examined. This research is funded by the Spanish Ministerio de Educacion y Ciencia and European Regional Development Funds (FEDER) (grants PSI2013-48260, PSI2010-19372, SEJ2007-62312, SEJ2004-01332, BSO2001-0693), the Regional Government of the Balearic Islands, and the private foundation La Marato TV3.