The primary olfactory (or piriform) cortex is a trilaminar paleocortex that is thought to construct unified “odour images” from the odour components identified by the olfactory bulb. How the piriform cortex (PC) accomplishes this sophisticated synthetic task, despite its relatively simple architecture, is unknown. One strategy for studying the PC is to take a bottom-up cell physiological approach using in vitro patch-clamp recordings from acute slices of the PC. I will describe some of our recent slice experiments that identify the basic microcircuits involved in excitatory and inhibitory synaptic processing in the PC. I will also present some new data about sensory processing by inhibitory circuits in the PC using in vivo and in vitro approach.