Olfaction modulates cortical arousal independent of perceived odor intensity and pleasantness

Throughout history, different odors have been harnessed to invigorate or relax the mind. The mechanisms underlying odors’ diverse arousal effects remain largely unexplored. We conducted five experiments (184 participants) to investigate this issue, using pupillometry, electroencephalography, and the attentional blink paradigm, which exemplifies the limit in attentional capacity. Results demonstrated that exposure to citral, compared to vanillin, enlarged pupil size, reduced resting-state alpha oscillations and alpha network efficiency, augmented beta-gamma oscillations, and enhanced the coordination between parietal alpha and frontal beta-gamma activities. In parallel, it attenuated the attentional blink effect. These effects were observed despite citral and vanillin being comparable in perceived odor intensity, pleasantness, and nasal pungency, and cannot be explained by semantic biases. Our findings reveal that odors differentially orchestrate cortical alpha and beta-gamma oscillations to alter brain state and arousal. Furthermore, they establish arousal as a unique dimension in olfactory space, distinct from intensity and pleasantness.