Replicating our prior findings using CSD-PCA methodology, the morphology of olfactory ERPs in response to H2S stimuli, which consists of the two major components named N1 and P2 (e.g., Lorig, 2000; Pause & Krauel, 2000), is efficiently represented by two distinct neuronal generator patterns at scalp, which we have termed N1 sink and P2 source (Kayser et al., 2010). However, the distinct sequence of N1 sink, peaking around 350 ms, and P2 source, peaking approximately between 500 and 800 ms, appears to be rather generic, as a highly comparable olfactory CSD component complex has been also observed for citronalva, a pleasant odorant with a lemony smell (Kayser et al., 2012). That study also found that N1 sink was closely related to individual ratings of arousal, whereas P2 source was associated with individual ratings of odor valence, suggesting a functional dissociation between these two olfactory components. This agrees with the proposition that early aspects of olfactory processing, such as odor categorization, are reflected by N1 sink, whereas P2 source reflects later aspects of olfactory processing, such as odor evaluation (Kayser et al., 2010).
