Localized denervation demonstrates the innervation pattern of olfactory bulb glomeruli and second order cells

Area of Science:

• Neuroscience
• Sensory Systems Biology
• Olfactory System Research

Background:

• Sensory systems require precise spatial organization for signal transmission.
• The mammalian olfactory nerve exhibits regional topographical organization, but variations are poorly understood.

Purpose of the Study:

• To evaluate the precision of olfactory bulb glomerular innervation from the olfactory nerve layer (ONL).
• To investigate the spatial variation in olfactory nerve fiber projections to the olfactory bulb.

Main Methods:

• Small cuts were made across olfactory nerve fibers in the ONL.
• Denervation was assessed using wheat germ agglutinin-horseradish peroxidase (WGA-HRP) labeling.
• Field potential measurements were used to support anatomical findings.

Main Results:

• ONL cuts on the lateral olfactory bulb created a distinct denervation stripe, indicating precise termination.
• Olfactory nerve fascicles showed limited deviation (1-2 glomerular widths) in their entry into denervated regions.
• Similar cuts on the dorsal surface did not produce a distinct denervation stripe, suggesting less precise organization.

Conclusions:

• Primary olfactory axons and their terminals are organized in parallel along the lateral olfactory bulb.
• This spatial organization is maintained in second-order neuronal connections.
• The findings facilitate the study of spatial aspects in olfactory coding mechanisms.