(A–D) Brain regions that are uniquely positively connected to each of the primary olfactory subregions including the (A) anterior olfactory nucleus (AON, red), (B) olfactory tubercle (TUB, purple), (C) frontal piriform cortex (PirF, blue) and (D) temporal piriform cortex (PirT, green). The results are shown on the FSL’s MNI152_T1_1mm_brain. (E–H) Functional connectivity maps shown on Freesurfer's cvs_avg35_inMNI152 brain surface for AON, TUB, PirF and PirT. All functional connectivity maps were thresholded at threshold-free cluster enhancement corrected p<0.001. L, left hemisphere; PHN, posterior hypothalamic nucleus; ITG, inferior temporal gyrus; OFC, orbitofrontal cortex; INS, insula; PCC, paracingulate cortex; RN, retromammillary nucleus; ACCU, accumbens; RSC, retrosplenial area; FP, frontal pole; FFA, fusiform face areas; ACC, anterior cingulate cortex; THAL, thalamus; CAU, caudate; PUT, putamen; SUP, supramarginal gyrus; TP, temporal pole; HIPP, hippocampus; BA, Broca’s area.