A fundamental quest in Neuroscience research is to reveal the function(s) of single neurons and networks. Understanding function seems to be on relatively solid grounds at the periphery where both anatomy and physiology converge in a simplified manner. However, as one ascends higher into the central nervous system, anatomy and physiology become increasingly more complex and functions become difficult to study. To reveal function, we will take a structure/function approach that synergizes between anatomical, physiological and behavioral methods. Namely, we will study the physiology of identified neurons to a rich set of stimuli bearing different behavioural contingencies and in the context of their anatomical boundaries. Specifically, my proposal aims to uncover function and structure of the mouse auditory cortex. First, we will redefine local and distant functional architecture in the auditory cortex using novel tracing techniques. Second, we will test a specific hypothesis whereas individual cortical neurons are multifunctional and part of distinct but multiple sub-networks. Third, we will use novel genetic techniques to tag and manipulate distinct cortical processing streams that are active during natural behaviors and specific learning paradigms. These experiments will answer whether specific sub-networks are instructive, permissive or necessary for perception. Finally, we will study how single neurons and sub-networks change in face of perceptual learning. As a whole, the main premise of this grant is to set the stage for, and eventually crystallize the experimental means to tease out functional diversity of single neurons in complex anatomical networks. Charting these basic principles for single neurons will impact how we study neuronal function and plasticity not only in the auditory system but across the mammalian brain.