Characterization of neural plasticity in monkey models of neuropathic pain

Abstract

Neuropathic pain can occur as a result of injuries and diseases of nervous system. Animal models using rodents have been developed and characterized to reveal plastic changes underlying neuropathic pain. However, structures and functions of some brain areas that are associated with pain perception differ between rodents and primates. Therefore, animal models using non-human primates, such as the macaque monkey, with brain structures and functions closer to those of humans are important for elucidating the mechanisms underlying pain in human patients. Recently, we measured brain activity using functional magnetic resonance imaging (fMRI) in a macaque model of chemotherapy-induced neuropathic pain and reported abnormal activation of pain-related brain regions including insular and secondary somatosensory cortices. In the monkey model of central post stroke pain, moreover, the increased activation of pain-related areas as seen in the patients was confirmed by fMRI. These results indicate that fMRI measurement of brain activity combined with behavioral outcomes in macaque models could be used not only to understand the pathogenetic mechanisms but also to test therapeutic interventions for neuropathic pain.