The terminal nerve projects centrally in the hamster

Area of Science:

• Neuroscience
• Anatomy

Background:

• The terminal nerve's projections and function remain incompletely understood.
• Investigating neural pathways from the nasal cavity to the brain is crucial for understanding sensory processing.

Purpose of the Study:

• To determine the projection pathways and direction of conduction of the hamster terminal nerve.
• To elucidate the role of the terminal nerve in sensory information transfer from the nasal cavity.

Main Methods:

• Lesion techniques were employed to transect the terminal nerve at various levels.
• Immunocytochemical methods, specifically using luteinizing hormone-releasing hormone (LHRH) as a marker, were used to trace nerve fibers.

Main Results:

• Transection experiments consistently indicated a centripetal (towards the brain) direction of conduction for terminal nerve axons.
• Peripheral lesions disrupted terminal nerve fibers in the terminal ganglion, but projections to the accessory olfactory bulb and ventral forebrain remained intact.
• Immunoreactive material accumulated proximal to lesions, confirming axonal transport direction.

Conclusions:

• The terminal nerve exhibits centripetal projections from nasal cavity neurons to the brain, likely serving as a pathway for neural messages.
• The presence of fibers in the vomeronasal organ suggests a sensory or sensory modulatory function for this nerve.