Nonsynaptic diffusion neurotransmission and brain plasticity

Nonsynaptic diffusion neurotransmission (NDN) includes the diffusion, through the extracellular fluid, of neurotransmitters released at points that may be remote from the target cells, with the resulting activation of extrasynaptic receptors. Because receptor upregulation and downregulation in response to brain damage may be one of the mechanisms of compensation for damage and sensory loss, its role in brain plasticity is considered in this article.