Cortical Reintegration After Facial Allotransplantation

Neural plasticity of the brain or its ability to reorganize following injury has likely subtended the successful clinical correction of severe deformity by facial transplantation since 2005. In this study we present the cortical reintegration outcomes following syngeneic hemifacial vascularized composite allograft (VCA) in a small animal model. Specifically, changes in the topographic organization and unit response properties of the rodent whisker-barrel somatosensory system were assessed following hemifacial VCA. Clear differences emerged in the barrel-cortex system when comparing naïve and hemiface transplanted animals. Neurons in the somatosensory cortex of transplanted rats had decreased sensitivity albeit increased directional sensitivity compared to naïve rats and evoked responses in transplanted animals were more temporally dispersed. Additionally, receptive fields were often topographically mismatched with indication that the mismatched topography reorganized within adjacent barrel (same row-arc bias following hemi-facial transplant). These results suggest subcortical changes in the thalamus and/or brainstem play a role in hemifacial transplantation cortical plasticity and demonstrates the discrete and robust data that can be derived from this clinically relevant small animal VCA model for use in optimizing post-surgical outcomes.