Strategies for Odor Coding in the Piriform Cortex

Principal cells in the piriform cortex. A, Schematic of the piriform cortex, including the somata and dendrites of the three types of principal cells: SP (green), SL (blue), and deep pyramidal (DP; gray). The activity of DP cells was not addressed by Suzuki and Bekkers (2006). The LOT, a bundle of mitral and tufted cell axons, projects from the MOB to the piriform cortex and makes synapses with the principal cells in layer I. B, LOT nerve stimulation (Stim.). The SP and SL cell output is related to the strength of the stimulus. Top, When the LOT is stimulated just above threshold, a small subset of LOT fibers is recruited (shown as red fibers). Although the SP cell fires with each LOT action potential, the SL cell does not. Bottom, At a higher stimulus intensity, the SP cell fires more frequently, whereas the SL cell closely follows the stimulus frequency.