Physiology and connectivity of syngeneic embryonic tissue grafts replacing injured visual cortex in adult rodents
Résumé
A major issue of transplantation studies in the adult brain is to examine the capacity of CNS or PNS grafts to reduce lesion-induced deficits, thus to explore their potential use for the treatment of neurological disorders in humans. Accordingly, most experiments refer to Parkinson’s and Hutington’s diseases which are both more or less directly related to the degeneration of so-called ‘diffuse’ projection systems. When grafting concerns ‘point-to-point’ neural systems – the function of which derives essentially from the precise arrangement of multiple connections between accurate neuronal assemblies – a further topic is to determine the degree to which grafts are able to repair the original pattern of connectivity. In addition to routine anatomical and histochemical approaches, investigation of some well known key features of the system under study by electrophysiological methods may provide decisive arguments to estimate how normal are both the host-graft pattern of connectivity and the functional properties of the graft neurons. Compared to other ‘point-to-point’ network models, the visual system offers this possibility. Present paper reviews anatomical and functional aspects of embryonic cortical tissue grafts aimed at replacing damaged cortical visual areas in adult rodents.