BOLD fMRI of C-Fiber Mediated Nociceptive Processing in Mouse Brain in Response to Thermal Stimulation of the Forepaws

摘要: Functional magnetic resonance imaging (fMRI) in rodents enables non-invasive studies of brain function response to peripheral input or at rest. In this study we describe a thermal stimulation paradigm using infrared laser diodes apply noxious heat the forepaw mice order nociceptive processing. Stimulation 45 and 46°C led robust BOLD signal changes various structures including somatosensory cortices thalamus. The amplitude scaled with temperature applied but not area irradiated by beam. To demonstrate specificity for assessing signaling administered quaternary lidocaine derivative QX-314 forepaws, which due its positive charge cannot readily cross biological membranes. However, upon activation TRPV1 channels following administration capsaicin was largely abolished, indicative selective block C-fiber nociceptors having entered cells via now open channels. This demonstrates that cerebral paw is specifically mediated C-fibers.