Sensory information in rodents is transmitted from the whiskers on the snout via the thalamus to the barrel cortex. The barrel cortex is part of the primary somatosensory cortex and consists of ellipsoid-shaped barrels. Remarkably, the arrangement of the whiskers on the snout corresponds to the layout of the barrels in the barrel cortex. That means, each barrel represents one whisker. Within a barrel, different excitatory cell types are located which receive direct synaptic input from the thalamus. What kind of excitatory barrel cells are innervated by thalamic fibers? Do the fibers project to some selected cell types or do they target all excitatory cell types with the same preference? Is there a distinct incidence and strength of thalamo-cortical projections to the different barrel cells? With the help of acute thalamo-cortical brain slices, the connection between the thalamus and the barrel cortex was examined by in-vitro tracing and electrical stimulation. The excitatory cell types were analyzed by their physiological and morphological characteristics. Synaptic short-term plasticity in the different excitatory barrel cells was investigated in mouse for the first time.