A non-canonical feedforward pathway for computing odor identity

Elucidating neural circuits that enable robust odor identification remains a fundamental challenge in olfaction. The current leading model states that odor identity is computed within the piriform cortex (PC), drawing from mitral cell input from the olfactory bulb. Here we find that tufted cells, the other principal cell-type of the bulb, which strongly innervate the anterior olfactory nucleus (AON) instead, substantially outperform mitral cells in decoding both odor identity and intensity, acting in a largely feedforward fashion. Cortical feedback from PC specifically restructures mitral cell responses, while feedback from AON preferentially controls the gain of tufted cell odor representations, matching biases in feedforward connectivity. Leveraging cell-type specific analyses, we identify a non-canonical feedforward pathway for odor recognition and discrimination mediated by the tufted cells, and propose that bulb target areas, other than the piriform cortex, such as AON and olfactory striatum, are well-positioned to compute odor identity.