Activity-dependent plasticity in visual cortex

A major question in neuroscience is how appropriate connections are formed when the brain develops. It is well established that neural circuits are fine-tuned by experience during 'critical periods' in early postnatal life. In the visual system, closing o ne eye for only a few days during a critical period leads to decrease in the cortical representation of the deprived eye, and long lasting vision impairment despite a healthy eye. A long-standing and pivotal question for our understanding of the brains re markable adaptive capacity is to what extent the brains plasticity depends on physical rearrangement of the connections between nerve cells. The laboratory of Professor Michael Stryker, UCSF, combines profound knowledge of visual cortex with innovative me thods, making this an ideal place to study and understand the mechanisms of neocortical plasticity. I propose to identify the changes in the cortical circuit responsible for rapid, activity-dependent plasticity mechanisms of neural plasticity that operate s in the visual cortex, and to use these as a window to understanding the general principles of plasticity and network dynamics in neocortex. I will induce activity-dependent plasticity experimentally, and repeatedly monitor identified cells in order to d iscover morphological and functional changes of genetically labeled cell classes responsible for the rapid, long lasting changes in neuronal responses. This will be done at a single cell level using in vivo transcranial two-photon imaging in combination w ith calcium sensitive dyes. The significance of this project lies in the likelihood that the developing visual cortex will be a fruitful system for revealing the mechanisms on neocortical plasticity. Upon returning to Norway the new methodology will be in tegrated with my current knowledge of behavioral neuroscience in an effort to set up a lab devoted to the understanding of plasticity and development of cortical networks.