Sublaminar Subdivision of Mouse Auditory Cortex Layer 2/3 Based on Functional Translaminar Connections

Area of Science:

• Neuroscience
• Auditory Cortex Research
• Cellular Electrophysiology

Background:

• The cerebral cortex is layered, with layer 2/3 (L2/3) neurons exhibiting diversity.
• Rodent L2/3 cytoarchitecture is less defined than in primates, leaving cell class distinctions unclear.
• Understanding L2/3 neuron functional diversity is crucial for auditory processing.

Purpose of the Study:

• To investigate if L2/3 of the male mouse auditory cortex contains discrete neuronal subpopulations with specific functional microcircuits.
• To identify classes of L2/3 neurons based on their laminar and columnar input patterns and sublaminar location.

Main Methods:

• In vitro slice recordings with laser-scanning photostimulation.
• Hierarchical clustering of laminar connection patterns.
• In vivo calcium imaging in awake mice.

Main Results:

• Hierarchical clustering revealed multiple distinct classes of L2/3 neurons based on input patterns and location.
• Superficial L2 neurons showed greater columnar integration than deeper L3 neurons.
• L2 cells exhibited higher bandwidth, while L3 cells received more translaminar input from L4 and were less frequency-selective.

Conclusions:

• Rodent L2/3 is not homogenous but comprises several parallel microcircuits, similar to higher mammals.
• Sublaminar location within L2/3 dictates distinct functional properties and microcircuit integration.
• Functional diversity in L2/3 receptive fields arises from underlying variations in functional circuits.