title: Functional MRI detection of bilateral cortical reorganization in the rodent brain following peripheral nerve deafferentation.
abstract: Evidence is emerging for significant inter-hemispheric cortical plasticity in humans, opening important questions about the significance and mechanism for this long range plasticity. In this work, peripheral nerve deafferentation was performed on both the rat forepaw and hindpaw and cortical reorganization was assessed using functional MRI (fMRI). Sensory stimulation of the forepaw or the hindpaw in rats that experienced only partial denervation resulted in activation in only the appropriate, contralateral, primary somatosensory cortex (SI). However, 2-3 weeks following complete denervation of the rats' forepaw or hindpaw, stimulation of the intact paw resulted in fMRI activation of ipsilateral as well as contralateral SI. To address whether inter-cortical communication is required for this cortical reorganization, the healthy hindpaw SI representation was stereotaxically lesioned in rats which had the other hindpaw denervated. No fMRI activation was detected in the ipsilateral SI cortex after lesioning of the contralateral cortex. These results indicate that extensive inter-hemispheric cortical-cortical reorganization can occur in the rodent brain after peripheral nerve deafferentation and that cortical-cortical connections play a role in mediating this inter-hemispheric cortical reorganization.
authors.affiliation: Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, B1D728, 10 Center Drive, Bethesda, MD, USA.
authors.forename: Galit
authors.initials: G
authors.lastname: Pelled
authors.forename: Kai-Hsiang
authors.initials: KH
authors.lastname: Chuang
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Dodd
authors.forename: Alan P
authors.initials: AP
authors.lastname: Koretsky
mesh_terms: D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D001931:Brain Mapping; D004292:Dominance, Cerebral / Q000502:physiology*; D005552:Forelimb / Q000294:innervation; D006614:Hindlimb / Q000294:innervation; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D009121:Muscle Denervation; D009416:Nerve Regeneration / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology*; D010100:Oxygen / Q000097:blood*; D010525:Peripheral Nerves / Q000502:physiology*; D051381:Rats; D012683:Sensory Deprivation / Q000502:physiology*; D013003:Somatosensory Cortex / Q000502:physiology*
chemical_list: D010100:Oxygen