Specific and Plastic: Chandelier Cell-to-Axon Initial Segment Connections in Shaping Functional Cortical Network

Area of Science:

• Neuroscience
• Cellular Biology
• Computational Neuroscience

Background:

• The axon initial segment (AIS) is a critical neuronal domain for action potential initiation.
• Cortical projection neurons (PNs) receive GABAergic inputs from chandelier cells (ChCs) at the AIS.
• ChCs are thought to regulate neuronal excitability and network activity due to their extensive innervation patterns.

Purpose of the Study:

• To review the history and recent advances in understanding chandelier cells (ChCs) and their role in cortical circuits.
• To highlight the plasticity of the axon initial segment (AIS) and ChC-PN connections.
• To discuss the significance of AIS and ChC-PN plasticity in physiological and pathological conditions.

Main Methods:

• Review of existing literature and research findings.
• Utilizing modern genetic and molecular tools for investigation.
• Focus on structural and functional analyses of AIS and axo-axonic synapses.

Main Results:

• Chandelier cells (ChCs) form axo-axonic synapses with hundreds of projection neurons (PNs).
• Dynamic structural and functional changes occur at the AIS and ChC-PN synapses during development and network activity shifts.
• These plastic changes are crucial for cortical microcircuit wiring, refinement, and adaptation.

Conclusions:

• The plasticity of the axon initial segment (AIS) and chandelier cell (ChC)-projection neuron (PN) connections is pivotal.
• These plastic changes play a key role in shaping dynamic neural networks.
• Understanding this plasticity is essential for comprehending both normal brain function and disease states.