Sex differences modulate olfactory bulb volume-function relationships but not olfactory training-induced plasticity

Area of Science:

• Neuroscience
• Olfactory Research
• Neuroimaging

Background:

• Men typically have larger olfactory bulb (OB) volumes, while women exhibit superior olfactory performance.
• Olfactory training (OT) is known to induce structural changes in the OB.
• The influence of sex on OT-related neuroplasticity remains unclear.

Purpose of the Study:

• To investigate how sex differences modulate OB volume-function relationships.
• To examine sex-specific effects on OT-induced OB neuroplasticity.

Main Methods:

• 27 women and 11 men with acquired olfactory dysfunction participated.
• Sniffin' Sticks Test and T2-weighted MRI were performed before and after a 12-week OT program.
• OB volume was measured using ITK-SNAP.

Main Results:

• No significant baseline correlation between OB volume and TDI score in the pooled sample.
• Women showed a significant baseline correlation between OB volume and TDI, unlike men.
• OT led to bilateral OB volume increases and improved odor discrimination and TDI scores in the overall sample.
• Men had consistently larger OB volumes, but no sex-by-session interaction was observed for OT effects.

Conclusions:

• Sex can mask cross-sectional associations between OB volume and olfactory performance, necessitating sex-aware analysis.
• OT induces comparable OB volume increases across sexes, indicating similar training-induced structural plasticity.