[Functional neuronal plasticity].

INTRODUCTION: Thanks to the contributions made by neuroscientific research and the clinical evidence regarding the functional recovery of the central nervous system in the different motor, cognitive, linguistic and sensory spheres, we now know more about how the brain is built and its modifications. This recovery is possible due to the plasticity of the brain, its capacity to reorganise itself and to modify functions in order to adapt to both external and internal changes. This capacity is inherent to brain cells and allows cortical circuits to be repaired, integrates other cortical areas to carry out modified functions and responds to different disorders. It depends on genetic, neuronal and neurochemical factors and its limits can be manipulated through clinical and pharmacological intervention. DEVELOPMENT: The brain's capacity to adapt itself to changes is crucial in the development of the nervous system and has important repercussions on learning. The neuroanatomical, neurochemical and functional changes that take place during the reorganisation made possible by plasticity will facilitate the recovery acquisition of the functions involved (adaptive plasticity) and may hinder the development of others (maladaptive plasticity). This variability of the possible responses is related to the chronology of the lesion, the site that is affected, the state of the substrata that can take on the function and the type of function that is altered. The mechanisms responsible for facilitating this plasticity are different at any given time (fast and late plasticity), depending on the function that is altered, with expansion of the somatotopic representations in the motor cortex adjacent to the damage, interhemispherical transfer of language or crossed plasticity in the auditory or visual function. The neuropsychological pathology can appear linked to the lesion or secondary to a maladaptive plasticity.
CONCLUSIONS: Advancing in our knowledge of the intrinsic mechanisms of brain plasticity and synaptic regulation will lead us to understand the recovery of damaged or lost functions in the brains of children with special needs, and thus allow us to implement favourable clinical and pharmacological interventions.