Different molecular mechanisms cooperate to the regulation hormones, local metabolic of brain microcirculation: products, transmitterso Great interest has recently emerged in literature on the neuronal systems controlling the blood- brain barrier and on the reciprocal interaction between neuronal activity and vascular supply. In particular, this volume on the NATO Advanced Research Workshop held in Salo' (BS), Italy, September 3-8, 1988, outlines the importance of neuron-vessel communication in the regulation of cerebral microenvironment. The problem is approached from a multidisciplinary point of viev, with contributions coming from basic and clinical areas. Stimulating results emerge from in vivo imaging techniques which allow the investigation of the hemodynamic and metabolic activities of the brain in various physiological and pathological conditions, such as aging or dementia. This methodology is of fundamental importance to acquire deeper knowledge on the relationship between cerebral blood flow, metabolism and higher brain funetions. Another stimulating aspeet addressed in this volume is the role of the glia in maintaining the homeostasis of the neuronal microenvironment, by "buffering" the excess of ions in the extracellular space and regulating the vascular transport processes. The complex interplay neuron-glia-vessel may indicate new perspectives in the therapy of cerebrovascular disorders, suggesting as a target for pharmacological intervention the VI neuronal (or glial) eelIs partieipating to the exchange of ions and substanees responsible for the extension of the isehemie damage.