A number of neurological diseases for which current therapies are nonexisting or inadequate involve deficit function of astrocytes, the predominant glial cell in brain. Our knowledge of astrocytes has lagged behind that of neurons, in particular when it c ome to their roles in neuronal signaling. The project combines optogenetic probes and two-photon imaging to unravel mechanisms of astrocyte signaling at single synapses in the brain of living mice. The concept launched is that astrocyte AMPA receptors fac ilitates glial Ca2+ signals that regulate synaptic transmission and plasticity. To delineate the molecular mechanisms underlying astrocyte calcium signals we will combine gene knockout strategies with novel optical probes, electrophysiological recordings and two-photon laser scanning microscopy. The project is multidisciplinary and will promote collaboration betweeen Max Planck Institute for Medical Research, Heidelberg, and Centre for Molecular Medicine Norway, the Nordic EMBL Partnership, University of Oslo. The project will ensure establishment of cutting-edge technologies that will benefit numerous researchers within the Norwegian neuroscience community.