Integration of olfactory and visual objects with verbal cues: An fMRI study.
Poster presentation
Humans are often bad at identifying odors, but extremely skilled at identifying visual objects. A possible explanation is that olfaction may rely to a high degree on other senses to enhance identification, given the olfactory cortex’s direct association with integrative brain nodes. This idea was recently supported by a behavioural study in which we asked participants to match visual and olfactory target stimuli to preceding verbal cues that were either congruent or incongruent with the predicted targets’ identity. Olfactory target matching was more affected than visual matching by the cue-target congruency. Several studies have provided evidence that the piriform cortex (PC) is the key olfactory area responsible for generating predictive models of olfactory stimuli. Under the predictive coding framework, stimulus processing is generated not by expected stimuli, but by error signals responding to expectation violation. If olfactory identification is indeed more reliant on other senses than vision is, the PC and visual cortex (VC) should be differentially affected by expectation violations, and the subsequent patterns of neural activation should diverge more in the PC. Empirical results of an ongoing fMRI study testing this hypothesis will be presented at the ECRO meeting. In line with predictive coding research in vision, our preliminary data (n=15) show that the piriform cortex is more activated to incongruent olfactory stimuli. Additionally, we expect congruency to affect neural pattern decoding of olfactory targets more than visual targets. Finally, we expect the representational content of congruent stimuli to be more different from incongruent stimuli in the PC compared to the VC. This approach will yield new insights into how identities may be differentially represented in the sensory cortices of the brain. The research was supported by the Swedish Research Council (2020:00266) and Knut and Alice Wallenberg Foundation (2016:0229) to J.K.O.