Can We Explain Thousands of Molecularly Identified Mouse Neuronal Types? From Knowing to Understanding

Area of Science:

• Neuroscience
• Developmental Biology
• Computational Neuroscience

Background:

• The recent Whole Mouse Brain Atlas identified approximately 5300 molecularly defined neuronal types.
• Conventional brain models, such as the columnar model, are insufficient to account for this high neuronal diversity.

Purpose of the Study:

• To investigate the feasibility of existing brain models in explaining the large number of neuronal types.
• To propose an alternative model that can accommodate the observed neuronal diversity.

Main Methods:

• Analysis of the Whole Mouse Brain Atlas data.
• Critique of the conventional columnar brain model.
• Proposal and elaboration of the progenitor microzone model.

Main Results:

• The conventional columnar model, with its limited number of columns, cannot explain the existence of 5300 neuronal types.
• A model based on approximately 1250 distinct progenitor microzones, each producing multiple neuronal types over time, is proposed as a sufficient explanation.
• The prosomeric model, enhanced by secondary microzonation and clonal variation, approximates this proposed mechanism.

Conclusions:

• The conventional columnar model is inadequate for explaining the full spectrum of neuronal diversity observed in the mouse brain.
• A progenitor microzone-based model offers a viable framework for understanding how a large number of neuronal types can arise.
• Further research into progenitor microzones and their developmental outputs is warranted to fully elucidate brain complexity.