Sex-specific hemispheric differences in cortical activation to a bimodal odor

Area of Science:

• Neuroscience
• Sensory Perception
• Olfactory Neuroscience

Background:

• Most everyday odorants are bimodal, activating both the main olfactory and intranasal trigeminal systems.
• Limited research exists on differential processing of bimodal versus unimodal odorants.
• Understanding these interactions is crucial for sensory science.

Purpose of the Study:

• To investigate sex-dependent hemispheric differences in olfactory event-related potentials (ERP) in response to bimodal odors.
• To explore how the brain processes stimuli engaging multiple sensory pathways.
• To identify potential sex-based variations in early sensory processing.

Main Methods:

• Recording olfactory event-related potentials (ERP) in 34 healthy subjects (17 women) exposed to peppermint oil (a bimodal stimulant).
• Assessing olfactory sensitivity, trigeminal sensitivity, and hedonic ratings.
• Analyzing hemispheric differences in ERP components.

Main Results:

• No significant sex differences were found in olfactory sensitivity, trigeminal sensitivity, or hedonic ratings.
• A sex-differentiated hemispheric response to bimodal odors was observed.
• Women showed larger amplitudes and longer latencies over the left hemisphere; men showed a similar pattern over the right hemisphere.
• These differences were most pronounced in early sensory-derived ERP components.

Conclusions:

• Bimodal odorants elicit sex-dependent hemispheric processing differences, despite similar subjective perception.
• Early sensory processing of bimodal odors differs between sexes, with distinct lateralization.
• This highlights a novel sex-based divergence in the neural processing of combined olfactory and trigeminal stimuli.