Recordings of mice layer IV barrel cortex activity using two-photon functional microscopy and Smart Line Scanning

Two-photon functional imaging using genetically encoded calcium indicators (GECIs) is one prominent tool to map neural activity. Under optimized experimental conditions, GECIs detect single action potentials in individual cells with high accuracy. However, using current approaches, these optimized conditions are never met when imaging large ensembles of neurons. Here, we developed a method that substantially increases the signal-to-noise ratio (SNR) of population imaging of GECIs by using galvanometric mirrors and fast smart line scan (SLS) trajectories. We validated our approach in anesthetized and awake mice on deep and dense GCaMP6 staining in the mouse barrel cortex during spontaneous and sensory-evoked activity. Compared to raster population imaging, SLS led to the availability of data with increased SNR and higher probability of detecting calcium events. Here, we share an example of a raster acquisition and multiple SLS acquisitions: such data can be used to perform population activity studies and to get a more precise identification of functional neuronal ensembles.