The research program aims to understand the dynamics of the structural and functional organization of the visual cortex and the implications for amblyopia ('lazy eye', the most prevalent visual disorder among young people). We will study these fundamental issues from the molecular level all the way to the network level. To achieve this, members of the consortium have - for the first time - established chronic in vivo two photon imaging of Ca2+ responses in the visual cortex by making use of a novel genetically encoded Ca2+ sensor. Using this powerful new methodology we will study how experience changes firing properties of individual neurons of known identity and how this correlates with changes in inhibitory and excitatory synaptic structures. Using the same approach we will study the neuronal substrate of amblyopia and how it alters coding of visual information. Next we will study how binocular experience leads to recovery from amblyopia and how perceptual learning can improve this in animal models and human subjects. This knowledge will be directly translated into new treatments of amblyopia by one of the participating SMEs. Last we will study the molecular and cellular mechanisms that restrict plasticity in the adult visual system with the aim to achieve increased experience dependent plasticity in the adult brain. This knowledge can be used for the treatment of disorders of the CNS from which recovery is limited due to restricted plasticity. Apart from amblyopia, these include brain tumors, stroke, degenerative diseases and trauma. Together this program will provide comprehensive insight into the neuronal interactions underpinning function and dysfunction of the visual cortex and will contribute directly to improved treatment of amblyopia and development of plasticity based approaches for curing a large array of disorders of the CNS.