A key goal of modern neuroscience is to understand the neural circuits and synaptic mechanisms underlying sensory perception. Here, I will discuss our efforts to characterise sensory processing in the mouse barrel cortex, a brain region known to process tactile information relating to the whiskers on the snout. Each whisker is individually represented in the primary somatosensory neocortex by an anatomical unit termed a 'barrel'. The barrels are arranged in a stereotypical map, which allows recordings and manipulations to be targeted with remarkable precision. In this cortical region it may therefore be feasible to gain a quantitative understanding of neocortical function. We have begun experiments towards this goal using whole-cell recordings, viral manipulations, optogenetics and two-photon microscopy. Through combining these techniques with behavioral training, our experiments provide new insight into sensory perception at the level of individual neurons and their synaptic connections. The talk will focus on the different activity patterns of five types of neocortical neurons located in layer 2/3 of the C2 barrel column: i) excitatory neurons projecting to M1; ii) excitatory neurons projecting to S2; iii) inhibitory neurons expressing parvalbumin; iv) inhibitory neurons expressing somatostatin; and v) inhibitory neurons expressing vasoactive intestinal peptide.