Retinal ganglion cells regenerate long-distance axons through neural activity stimulation and find their way back to the brain

Human central nerve system (CNS) is an extremely complex and delicate structure. While regeneration is possible in some reptiles and fish CNS, the regeneration capacity seems completely lost in adult mammals. Therefore, the classic concept is that once neurons in mammal CNS are damaged in injury or disease, they cannot regenerate themselves anymore. Although we have known this feature of mammals CNS for quite some time, many scientists have never given up their dreams in finding the “Elysium” for CNS regeneration. In newborn children and in very rare cases of adult humans, we do see, amazingly, some reports that show successful regeneration of CNS neurons or their axons (1). From a clinical perspective, however, regeneration of neuron or its axon is still not good enough. The key issue to address is to reestablish neural circuit connections with functional neural electric activities.