Damaged central nervous system fibres within an injured mouse brain have the ability to redevelop in uninjured areas at speeds comparable to nerve regeneration in the peripheral nervous system. The findings, reported in Nature Communications this week, contradict the commonly held belief that the central nervous system lacks the ability to regenerate after injury.
Injury to the central nervous system results in many microscopic structural changes and can result in a wide range of effects, including paralysis, slurred speak and muscle weakness. While much of the work in this area of research has focussed on the spinal cord and white matter of the central nervous system, our understanding of the changes that occur in the neuron-rich grey matter is limited. Vincenzo De Paola and colleagues use time-lapse microscopy to monitor the response of neuronal circuits in the injured brains of living mice over the course of a year. They find that specific types of nerve fibres can spontaneously regrow over distances that are not normally seen in the uninjured brain and that this is in part, due to an absence of nearby glial scars that secrete inhibitory growth factors.
Although the authors acknowledge that they do not fully understand the mechanisms of axon regeneration in the mammalian brain, they hope that these microscopic approaches will be useful for testing repair strategies in ways not previously possible.