Low grade gliomas and cerebral plasticity: fundamental and clinical implications

Post-lesional plasticity (PLP) describes the processes that reorganize cerebral connections after an injury. Since Broca's influential contribution and the common endorsement of "localisationist" models of brain physiology, it has been widely admitted that PLP was limited, not to say impossible in the so-called "eloquent areas". However, recent observations associated with the surgical treatments of low grade gliomas have called this dogma into question. Indeed, more and more evidence suggest that large cerebral resections can be compensated so efficiently that no functional deficits can be detected after the surgery. Pre and post surgical investigations based on imaging techniques, as well as intra-surgical investigations involving electrical stimulations, allow to track the nature and the temporal characteristics of these compensations. Compensatory reactions begin before the operation, in response to the tumoral growth. They remain active during and after the surgery. These compensations can involve the perilesional adjacent areas, the distant ipsilateral cerebral structures and the homologous contra-lateral regions. When considered together these results have obvious fundamental and clinical implications. They open new perspectives for understanding cerebral dynamics and the process of brain plasticity.