Stepwise pathways from the olfactory cortex to central hub regions in the human brain

Area of Science:

• Neuroscience
• Cognitive Science

Background:

• The human brain's hierarchical network connects sensory cortices to association cortices.
• Central cortical hubs, like the default-mode network (DMN), are crucial for language.
• The functional connectivity of the olfactory system to the DMN remains unclear.

Purpose of the Study:

• To investigate the functional connectivity and connective distance between olfactory regions and the default-mode network (DMN).
• To identify distinct olfactory pathways and their access to central cortical networks.

Main Methods:

• Functional connectivity analysis was used to map pathways from olfactory seed areas to the DMN.
• Olfactory cortical subregions were parcellated to differentiate pathways.
• Results were validated using a replication cohort.

Main Results:

• Olfactory pathways connect to the DMN in three to four intermediate steps.
• Two distinct olfactory pathways were identified.
• One pathway provides early access to the orbitofrontal cortex; the other involves the piriform cortex, anterior insula, and other regions.

Conclusions:

• Olfaction exhibits unique, early access to central cortical networks through dual pathways.
• These findings contribute to understanding the integration of sensory information in large-scale brain networks.