De Novo Emergence of Odor Category Representations in the Human Brain.

How the human brain assigns novel odors to perceptual classes and categories is poorly understood. We combined an olfactory-visual paired-associates task with multivariate pattern-based fMRI approaches to investigate the de novo formation of odor category representations within the human brain. The identification of emergent odor category codes within the perirhinal, piriform, orbitofrontal, and insular cortices suggests that these regions can integrate multimodal sensory input to shape category-specific olfactory representations for novel odors, and may ultimately play an important role in assembling each individual's semantic knowledge base of the olfactory world.