Brain-Computer Interfaces (BCIs) are devices designed for communication between the central nervous system and a computer. The communication can occur through different sensory modalities, and most commonly visual and auditory systems are used. We suggest that BCIs can be expanded by the incorporation of olfactory modality. To probe the modulation of EEG activity by odorants, we implemented two olfactory tasks: one that required attention to perception of odors, and the second one where participants discriminated consecutively presented odors. EEG recordings were conducted in 13 healthy participants while they performed the tasks following computer-generated verbal instructions. Respiratory activity was recorded to relate EEG modulations to the breath cycle. Theta activity responses were observed over the frontal EEG leads approximately 2 s after the inhalation. This theta activity was different depending on whether or not the inhaled air contained an odorant, and cognitive load also had an effect. We conclude that the frontal theta rhythm is reflective of the neural processing of odors. As such, it could be incorporated in the olfactory-based BCIs which take odors either as inputs or outputs. These BCIs could improve olfactory training needed for conditions like anosmia and hyposmia, and mild cognitive impairment.

Brain-Computer Interfaces (BCIs) are devices designed for establishing communication between the central nervous system and a computer. The communication can occur through different sensory modalities, and most commonly visual and auditory modalities are used. Here we propose that BCIs can be expanded by the incorporation of olfaction and discuss the potential applications of such olfactory BCIs. To substantiate this idea, we present results from two olfactory tasks: one that required attentive perception of odors without any overt report, and the second one where participants discriminated consecutively presented odors. In these experiments, EEG recordings were conducted in healthy participants while they performed the tasks guided by computer-generated verbal instructions. We emphasize the importance of relating EEG modulations to the breath cycle to improve the performance of an olfactory-based BCI. Furthermore, theta-activity could be used for olfactory-BCI decoding. In our experiments, we observed modulations of theta activity over the frontal EEG leads approximately 2 s after the inhalation of an odor. Overall, frontal theta rhythms and other types of EEG activity could be incorporated in the olfactory-based BCIs which utilize odors either as inputs or outputs. These BCIs could improve olfactory training required for conditions like anosmia and hyposmia, and mild cognitive impairment.