Sensory processing in the main and accessory olfactory systems: comparisons and contrasts.

Area of Science:

• Neuroscience
• Olfactory System Biology
• Animal Behavior

Background:

• The vomeronasal organ (VNO) and accessory olfactory system (AOS) are crucial for processing chemical signals (pheromones) in most terrestrial vertebrates, excluding birds and higher primates.
• Unlike main olfactory neurons, VNO receptor neurons are sequestered within the VNO, receiving stimuli via specialized pathways.
• VNO neurons lack cilia and project to brain regions associated with reproduction and social behavior, differing from the main olfactory system's broader neural connections.

Purpose of the Study:

• To elucidate the structure, function, and neural pathways of the vomeronasal organ (VNO) and accessory olfactory system (AOS).
• To investigate the role of the VNO/AOS in processing pheromones and mediating behavioral and physiological responses.
• To explore the potential involvement of LHRH in AOS-mediated behaviors.

Main Methods:

• Review of existing literature on VNO and AOS anatomy and function across vertebrate species.
• Analysis of experimental studies involving ablation of VNO or accessory olfactory pathway components.
• Examination of neurophysiological responses of VNO sensory neurons to various stimuli.

Main Results:

• The VNO/AOS is vital for behavioral and physiological responses to pheromones, including those related to reproduction and social status.
• VNO sensory neurons detect both volatile and non-volatile stimuli, with specialized delivery mechanisms.
• Evidence suggests learning capabilities within the AOS and a link to intracerebral LHRH release, potentially influencing behavior.

Conclusions:

• The VNO/AOS plays a significant role in pheromone detection and the regulation of social and reproductive behaviors in vertebrates.
• While not as sensitive as insect systems, the vertebrate AOS demonstrates specialized functions.
• Further research is needed to clarify the necessity of LHRH release for AOS-mediated behavioral responses.