Information for Decision Making and Stimulus Identification is Multiplexed in Sensory Cortex

In recordings from anterior piriform cortex (APC) in awake behaving mice we find that neuronal firing early in the olfactory pathway simultaneously conveys fundamentally different information: odor value – is the odor rewarded?- and identity- what is the smell? Thus, this sensory system performs early multiplexing of information reflecting stimulus–specific characteristics with that used for decision-making. The olfactory bulb converts a complex input from ~1,400 olfactory receptors1 into odor value after one or two synapses2,3. Synchronous firing of mitral cells then transfers information to the cortex3–5. The early olfactory system thus faces the challenge of transmitting information about both stimulus “value ” vs. “identity”. Multiplexing is one mechanism to simultaneously transmit this information6, but how information on odor value and identity is multiplexed is not understood. In humans, APC responds to olfactory stimuli when actively detecting odors, but shows reduced fMRI signals when the subject is passive7. Yet, even in passive sampling, odor identity is conveyed to detect deleterious odors. Here we ask whether transmission of information regarding identity and value through APC is multiplexed, and whether coding differs during active vs. passive monitoring. In the active odor detection task the mouse received water for licking when presented rewarded odors, and not when exposed to unrewarded odor (Fig. 1, Supplementary Figs. 1– 4). They responded correctly in 87±6 % of trials (±SEM, n=20). As expected4,5, odors elicited changes in firing rate that differed between rewarded and unrewarded (Fig. 1). A Users may view, print, copy, download and text and data- mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use