Towards a "canonical" agranular cortical microcircuit.

Area of Science:

• Neuroscience
• Computational Neuroscience
• Neuroinformatics

Background:

• The widely adopted "canonical" cortical microcircuit is based on striate cortex, characterized by dense cells and distinct layers.
• Other cortical regions exhibit varying architectures, from eulaminate to dysgranular and agranular areas with less differentiation.
• Intrinsic circuitry is unlikely to be uniform across these diverse cortical structures.

Purpose of the Study:

• To define local microcircuits for agranular cortical regions as a contrast to the striate cortex model.
• To investigate potential variations in intrinsic circuitry across different cortical types.
• To explore the functional relevance of these variations.

Main Methods:

• Synthesis of existing literature on local microcircuitry in rodent agranular cortical areas.
• Review of anatomical and electrophysiological studies.
• Comparative analysis with the established striate cortex microcircuit.

Main Results:

• A tentative microcircuit for agranular cortex is proposed.
• A weakening of interlaminar inhibition is observed as cortical cytoarchitecture becomes less distinctive.
• Deviations from the canonical microcircuit in agranular regions were identified.

Conclusions:

• The canonical microcircuit model may be specific to highly differentiated areas like the striate cortex.
• Intrinsic circuitry varies across the cortex, particularly in agranular regions.
• These variations in cortical microcircuits likely have functional implications.