Previous studies of this group examined the masking effect of eucalyptol when in a mixture with ammonia both on a behavioral, physiological and neural network level. We were able to find that eucalyptol can mask the olfactory, but not the trigeminal sensation of ammonia. Furthermore, behavioral data showed that only half the participants perceived the odor mixture as pleasant, which is a precondition for malodor coverage. The other half perceived the odor mixture as unpleasant, which was also apparent on a neuronal level, where these participants showed activation in the anterior insula and SII, indicating an attentional shift towards the unpleasant ammonia odor. While examining the signal intensity in other brain regions involved in odor processing, namely piriform cortex, anterior midcingulate gyrus, inferior frontal gyrus and anterior insula, we found both an expected peak at approximately 8 sec after stimulus presentation as well as an unexpected second peak at around 26 sec after stimulus presentation. Our ongoing analysis of this phenomenon concentrates on multiple aspects: First, we suspect a correlation with respiratory data, therefore we are currently using multiple regression approaches to examine the effect of respiration on the neurological correlates. Second, a delayed trigeminal sensation could be the reason. It is possible that the task to rate the pleasantness of the stimulus causes this delayed response, potentially by triggering an unconscious deep inhalation and therefore a repeated perception of the stimulus. Third, we aim to apply multi-voxel pattern analysis with which activation patterns can be used to better differentiate the initial stimulus. These analyses will be accompanied by a behavioral study examining the effect of the pleasantness rating and a deeper inhalation on odor intensity perception. We will here discuss several options for the explanation of the delayed neural network response to olfactory-trigeminal stimulation.