Ten years ago, OPA1 was identified as the major gene responsible for hereditary optic nerve degeneration, evidencing the first defect in mitochondrial network dynamics as the princeps pathophysiological mechanism in a mitochondriopathy. Later, alterations in other genes involved in mitochondrial fusion or fission, such as MFN2, DRP1 and GDAP1, were also associated with inherited neurological diseases, mainly affecting peripheral nerves. More recently, altered mitochondrial plasticity was also demonstrated in common age-related neurodegenerative disorders, as Alzheimer and Parkinson diseases, thus substantiating the critical role of mitochondrial dynamics in neurons as a key element governing the efficiency of oxidative respiration and its distribution along the axons.