Plasticity is a natural ability of the nervous tissue to respond to stimuli of the internal and external environment by long-term or permanent changes of its activity. Genetic programes of development, adaptation and recovery are subjected to the actual state of the neural microenvironment, which reflects the balance between destabilising factors (activity of neurones), and those which tend to stabilise it (activity of glial elements, controlled permeability of the blood brain barrier). Properties of the microenvironment are determined by the extracellular matrix.Components of this system influence the flow of fluids and form the environment for the neuronal migration and for the growth of dendritic and axonal processes. Reactions of the vascular system can also contribute to the stability of the neural microenvironment. They are based on perfusion changes and permeability of the blood-brain barrier. Structural and functional properties of the barrier form and maintain the specific composition of the neural microenvironment. Permeability of the blood-brain barrier is subjected to changes during the development and during some pathological states. Penetration of macromolecular substances into or from the injured region may reflect the pathway for spreading of signalling molecules, which can make the integration of the impaired and healthy tissue possible. Artificial elevation of permeability may help penetration of such substances, which could activate programmes of neuroplastic processes of adaptation or recovery of neuronal circuits.

        Key words: neuroplastic processes, neural microenvironment, extracellular matrix, blood-brain barrier