Visual and auditory processing in human olfactory cortex

Poster presentation

Evelina Thunell ^{1, 2, 3}, Behzad Iravani ¹, Moa Peter ¹, Danja Porada ¹, Katharina Prenner ¹, Johan N. Lundström ^{1, 4, 5, 6}

¹ Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden, ² Department of Psychology, Stockholm University, Stockholm, Sweden, ³ Department of Psychological Sciences, Purdue University, West Lafayette, IN, USA, ⁴ Monell Chemical Senses Center, Philadelphia, PA, USA, ⁵ Department of Psychology, University of Pennsylvania, Philadelphia, PA, USA, ⁶ Stockholm University Brain Imaging Centre, Stockholm University, Stockholm, Sweden

The piriform cortex, considered part of the primary olfactory cortex, has been found to respond also to stimuli in other modalities in certain conditions. Here, we use fMRI (n = 47) to show that even in the absence of any reference to odors during the experiment, the posterior piriform cortex (PPC) is activated by both pictures and sounds of objects. We also found significant activation by sounds, but not pictures, in the anterior piriform cortex (APC). These activations were elicited both by objects receiving low and high odor association ratings in a post-experiment rating task. In visual and auditory brain regions, we found cross-activations: Pictures activated higher-level auditory cortex and elicited a decreased BOLD signal in primary auditory cortex (A1), and sounds activated primary visual cortex (V1) and elicited a decreased signal in the higher-level visual area LOC. These findings further question the notion of PPC and APC as purely olfactory regions, and in general contributes to a more nuanced picture of modality specificity in olfactory, auditory, and visual cortices. This work was supported by a grant from the Knut and Alice Wallenberg Foundation awarded to JNL (KAW 2018.0152).