Functional Reorganization in the Primary Somatosensory Cortex of Rat Following Hind-Paw Amputation: A Study of Functional Imaging with 1.5 Tesla MRI

AIM: To learn how rat primary somatosensory cortex (pSSC) responses to the loss of inputs from hind-paw, using fMRI of an inferior magnetic power (1.5 Tesla) with special designed high-powered rat coil. MATERIAL and METHODS: Ten adult male Sprague-Dawley rats were enrolled in this study. The rats were anesthetized with ketamine injection. Xylazine was intraperitoneally injected for analgesia and muscle relaxation with careful maintenance of spontaneous respiration. Either right or left hind-paws were amputated under aseptic conditions according to predefined random allocation of the rats. A 12-channel rat surface coil developed for proper image resolution in 1.5 Tesla MR was used. Functional magnetic resonance imaging was obtained before hind-paw amputation; 2, 15 and 30 days after the amputation. RESULTS: Activation signals were detected in 5 rats' contralateral pSSC before the hind-paw amputation with regression and cessation of the signal after the amputation. Signal re-appeared in the contralateral pSSC of only one rat (rat 9) 30 days after the amputation. CONCLUSION: This study showed that functional plasticity might occur in the pSSC following hind-paw amputation of rats. Further studies are necessary to understand the true nature of the plasticity observed in pSSC, with new and novel measurement techniques on cellular basis rather than gross anatomical one.