Intersectional monosynaptic tracing for dissecting subtype-specific organization of GABAergic interneuron inputs

Area of Science:

• Neuroscience
• Cortical circuits
• Cellular neurobiology

Background:

• Cortical principal neurons (PNs) have distinct subtypes.
• Cortical inhibitory interneurons (INs) regulate PN activity.
• The spatial organization of IN subtypes targeting specific PN subtypes is unknown.

Purpose of the Study:

• To develop a method for visualizing IN subtypes that innervate defined PN subtypes.
• To investigate the spatial organization of IN inputs to different PN subtypes.
• To understand the principles of cortical inhibitory circuit wiring.

Main Methods:

• Developed a genetic strategy combining recombinase-based intersectional labeling.
• Utilized rabies viral monosynaptic tracing for subtype-specific visualization.
• Mapped IN ensembles targeting defined PN subtypes.

Main Results:

• Revealed cardinal and underrepresented connections between IN and PN subtypes.
• Demonstrated that distinct PN subtypes (areal/laminar) have different IN input organizations.
• Enabled subtype-specific visualization of cortical IN ensembles.

Conclusions:

• The developed genetic strategy facilitates understanding of cortical inhibitory circuits.
• Distinct PN subtypes exhibit unique organizations of input IN subtypes.
• Provides a foundation for studying wiring and developmental principles of inhibitory circuits.