From Odor Percept to Perceptual Awareness

Another broad research focus in the lab is to characterize the behavioral impact of odor inputs at the boundaries of human olfactory awareness, with an emphasis on delineating the neural systems supporting conscious analysis of an odor stimulus. For example, we have shown that fMRI representations of odor objects are encoded in human piriform cortex (where they can be rapidly updated by perceptual and associative learning). On the other hand, it is unknown whether conscious awareness of these odor percepts arises directly from piriform cortex (an evolutionarily ancient three-layer paleocortex), or requires the participation of neocortical brain regions such as orbitofrontal cortex (OFC). Such findings would have important implications for understanding how the neural organization of human olfaction relates to other sensory modalities, and at a more speculative level, whether conscious sensory awareness might be expected in animals lacking an OFC (which includes all non-mammalian vertebrates: see Gottfried, Annals of the New York Academy of Sciences 2007). To address these issues, we are utilizing combinations of psychophysical, imaging, and patient lesion approaches.

Please click on the following links for some specific examples of this line of research.

Undetectable smells influence human social behavior

Thalamocortical network activity is necessary for conscious olfactory awareness