Efeito do ambiente sobre o período crítico de plasticidade do córtex pré-frontal de ratos

Abstract

The critical period of plasticity is a period of postnatal brain development in which neural circuits are most susceptible to environmental influence. The critical period of plasticity of the human prefrontal cortex, which is responsible for executive functions, extends from birth to the end of adolescence and early adulthood. The critical period is defined, among other factors, by the maturation of perineuronal nets, a specialized structure of the extracellular matrix, which surrounds cell bodies and proximal dendrites of inhibitory interneurons. The aim of the present work was to ascertain the effects of environmental, through different adolescence phases, on the morphofunctional structure of the prefrontal cortex of rats and the spatial and temporal distribution of perineuronal nets. Executive functions were also evaluated by testing working memory capacity and behavioral inhibition. We observed that the chronic exposure to unpredictable stressors cause changes the critical period of plasticity in the prefrontal cortex and thereby influence the maturation of executive functions. We also observed that chronic stress induces changes in the spatial and temporal expression of perineuronal nets in the prefrontal cortex. More specifically, it induces the early maturation of these structures in adolescent rat brain. These results indicate the vulnerability of the adolescent brain to the negative effects of chronic stressors present in the environment.