A marker mouse for conditional labeling of single neurons

One of the biggest tasks in modern neuroscience is to understand neuronal activity on the level of local networks. Therefore, it will be necessary to analyze neurons in the context of sensory stimulation or a behavioral task. However, the most powerful methods to investigate neuronal connectivity up to date are restricted to the brain slice preparation. In this grant proposal I am describing a strategy for the generation of a transgenic mouse, that will be key to investigate individual neurons in vivo as well as in the brain slice preparation. The basic principle will be the expression of photoactivatable/photoswitchable fluorescent proteins for labeling of individual living cells. This will enable us to investigate the very same neurons in vivo as well as in vitro. It will be important to choose the optimal fluorescent protein to be compatible with calcium indicators as well as providing an excellent signal to noise ratio. Such a transgenic mouse will be key to answer questions about the connectivity of neuronal assemblies that are forming during memory formation.

One of the biggest tasks in modern neuroscience is to understand neuronal activity on the level of local networks. Therefore, it will be necessary to analyze neurons in the context of sensory stimulation or a behavioral task. However, the most powerful methods to investigate neuronal connectivity up to date are restricted to the brain slice preparation. In the future it will be essential to be able to combine several analytical approaches to the same, functionally identified neurons. In the FWF-funded project, we implemented a strategy to generate transgenic mouse lines that allow investigation of individual neurons in vivo as well as in the brain slice. The basic principle is the expression of photoactivatable/photoswitchable fluorescent proteins for labeling of individual living cells. This allowed us to investigate the very same neurons in vivo as well as in vitro. Particular care was taken to choose the optimal fluorescent protein to be compatible with calcium indicators as well as providing an excellent signal to noise ratio. We generated several mouse lines expressing photoactivatable proteins in a constitutive or conditional manner and we demonstrated their versatility in several relevant experimental approaches. These novel mouse lines will crucially facilitate the combination of several analytical approaches on the same, photolabeled cells. As the photoactivatable proteins are expressed also on non-neuronal cells various applications arise also in other biomedical fields where it is of interest to label individual, living cells and to analyze them.