Axon-axon interactions in neuronal circuit assembly: lessons from olfactory map formation

Area of Science:

• Neuroscience
• Developmental Biology
• Molecular Biology

Background:

• Neuronal development relies on axon guidance via chemical cues.
• Previous research focused on target-derived cues for axon pathfinding.
• Emerging evidence highlights the significance of axon-axon interactions.

Purpose of the Study:

• To review the roles and mechanisms of axon-axon interactions in neuronal circuit assembly.
• To discuss the contribution of axon-axon interactions to olfactory map formation.
• To present the concept of 'self-organisation' in axon guidance.

Main Methods:

• Review of recent studies on axon guidance and neuronal circuit assembly.
• Analysis of experimental findings on olfactory map formation in vertebrates.
• Synthesis of data on pioneer-follower interactions and axon sorting.

Main Results:

• Axon-axon interactions are crucial for axonal pathfinding and neuronal circuit assembly.
• Pioneer-follower interactions establish topographic maps (e.g., anterior-posterior and dorsal-ventral).
• Axon sorting, influenced by secreted molecules and neural activity, underlies map formation.

Conclusions:

• Axon-axon interactions represent a fundamental principle in neuronal circuit assembly.
• Olfactory map formation exemplifies a 'self-organisation' process driven by axons.
• Understanding these interactions offers new insights into neural development and potential therapeutic targets.