The biology of astrocyte–neuron interaction has emerged as a rapidly expanding field and has become one of the most exciting topics in current neuroscience that is changing our understanding of the physiology of the nervous system. In the last few years, evidence obtained by many laboratories has established the existence of neuron-astrocyte communication in culture preparations and brain slices. However, the properties of astrocytes and their physiological role in vivo is largely unknown Numerous in vitro studies have focused on investigating the basic molecular mechanisms as well as the subcellular and cellular processes involved in astrocyte-neuron communication. Yet, to begin to understand the actual active role of astrocytes in the brain function, we need to analyze this communication and its effects at a higher level of complexity, such as during neural network function and information processing in vivo. The main objective of present project is to elucidate the impact of astrocytes in neural network function and sensory information processing in vivo. The achievement of the proposed objectives will increase our current knowledge of the role of astrocytes at a higher level of complexity, filling the gap currently existing on this area of neuroscience, and therefore, will significant extend our knowledge of the physiology and function of the nervous system. Using a conceptual interdisciplinary approach that will cover different levels of analysis (from molecules to cells and networks) to gain a comprehensive vision of the nervous system function, I propose to combine multidisciplinary techniques that include electrophysiology, Ca2+ imaging, two-photon microscopy in vitro and in vivo and genetic manipulation of animal models, to characterize the functional consequences of astrocyte activity in the sensory information processing by neural networks of the visual cortex.