Optogenetic fMRI reveals neural adaptation properties beyond local olfactory circuits

Olfactory adaptation due to repeated odor cues has been studied extensively by fMRI or electrophysiology studies in several primary olfactory regions (i.e., anterior olfactory nucleus, AON, and piriform cortex, Pir). However, the modulatory role of other primary olfactory regions (e.g., amygdala and entorhinal cortex) and their integrations with high-order olfactory regions during olfactory adaptation is likely underestimated due to the documented weak and unstable responses at regions beyond AON and Pir with conventional presentation of odor stimuli. Here, we deployed an optogenetic fMRI approach to improve sensitivity in detecting olfactory responses and examine their adaptation at the systems level.