Functional and structural features of L2/3 pyramidal cells continuously covary with pial depth in mouse visual cortex

Area of Science:

• Neuroscience
• Cortical Circuitry
• Cellular Physiology

Background:

• Pyramidal cells in neocortical layer 2/3 (L2/3 PyrCs) are crucial for integrating and distributing information across the cortex.
• Previous studies suggest pial depth-dependent specializations in L2/3 PyrCs, hinting at distinct functional roles within cortical microcircuits.

Purpose of the Study:

• To investigate whether L2/3 PyrCs represent discrete subtypes or a continuum of properties correlated with pial depth.
• To characterize depth-dependent variations in stimulus selectivity, electrophysiology, morphology, and connectivity of L2/3 PyrCs.

Main Methods:

• In vivo calcium imaging in mice to assess visual responsiveness.
• Electrophysiological recordings to measure neuronal properties.
• Dendritic morphology analysis.
• Excitatory and inhibitory connectivity mapping across L2/3 depth.

Main Results:

• Apical dendritic structure and subthreshold electrophysiology vary systematically with pial depth.
• Deeper L2/3 PyrCs receive more input from layer 4 and exhibit more robust visual responses, with stronger contralateral eye preference.
• Superficial L2/3 PyrCs receive more intralaminar input.

Conclusions:

• L2/3 PyrCs form a functional and structural continuum across pial depth, rather than discrete subtypes.
• Depth-dependent properties suggest specialization of L2/3 PyrCs for distinct roles within cortical microcircuits.