Dendrites and dendritic spines are made of fine, thin and vulnerable processes therefore they are difficult to study. However, using two-photon laser technology, we are able to collect signals from femtoliter volumes of deeper regions of the brain, while avoiding phototoxicity at the same time. Beside of this, spatially confined scanning of axons, dendrites and spines as ROIs allows detecting even subthreshold signals with high signal-to-noise ratio (SNR). We have several configurations with which we are able to visualize dendritic arborization, and perform functional measurements under in vivo and in vitro conditions.