Refining the dual olfactory hypothesis: pheromone reward and odour experience

Area of Science:

• Neuroscience
• Animal Behavior
• Chemosensation

Background:

• Rodent sexual communication relies heavily on chemosignals.
• Male sexual pheromones, particularly non-volatile components, are detected by the vomeronasal organ in female mice.
• Access to the vomeronasal organ requires active pumping during chemoinvestigation.

Purpose of the Study:

• To investigate the rewarding properties of male sexual pheromones in female mice.
• To explore the neural mechanisms underlying pheromone reward.
• To elucidate the distinct roles of the olfactory and vomeronasal systems in intersexual communication.

Main Methods:

• Conditioned place preference tests using male-soiled bedding as a reinforcer.
• Lesioning of the accessory olfactory bulbs in female mice.
• Assessment of behavioral responses to male-derived olfactory and vomeronasal stimuli.

Main Results:

• Male-soiled bedding can act as a reinforcer, establishing conditioned place preference in female mice.
• Neural mechanisms for pheromone reward differ from those of other natural rewards like sucrose.
• While olfactory stimuli are not initially attractive, repeated exposure leads to acquired preference in intact females.
• Accessory olfactory bulb lesions induce aversion to male odorants after exposure.

Conclusions:

• Male sexual pheromones are intrinsically rewarding to female mice via the vomeronasal system.
• The olfactory and vomeronasal systems play complementary roles in mediating attraction and communication.
• Experience and sensory system integrity critically influence responses to social chemosignals.