Differences and similarities between human and chimpanzee neural progenitors during cerebral cortex development

Area of Science:

• Developmental biology
• Evolutionary biology
• Neuroscience

Background:

• Human cognitive abilities are linked to neocortex expansion.
• Neocortex expansion is hypothesized to stem from differential proliferation and differentiation of neural progenitors.
• Comparative analysis of human and chimpanzee cortical development is crucial for understanding human evolution.

Purpose of the Study:

• To investigate differences in neural progenitor proliferation versus differentiation between human and chimpanzee cerebral organoids.
• To identify molecular and cellular mechanisms underlying human neocortex expansion.

Main Methods:

• Generation and analysis of human and chimpanzee cerebral organoids.
• Immunohistofluorescence and live imaging to observe progenitor cell behavior.
• Single-cell transcriptomics to analyze gene expression profiles.

Main Results:

• Overall similarity in cytoarchitecture, cell types, and neurogenic gene expression between human and chimpanzee organoids.
• A specific lengthening of prometaphase-metaphase during apical progenitor mitosis in humans compared to chimpanzees.
• Increased expression of proliferation-related genes and a lower proportion of neurogenic basal progenitors in human organoids.

Conclusions:

• Subtle differences in neural progenitor cell cycle dynamics, specifically during mitosis, exist between humans and chimpanzees.
• These progenitor differences, including extended prometaphase-metaphase and altered progenitor proportions, may contribute to human neocortex expansion.
• Findings provide insights into the evolutionary mechanisms driving human cognitive uniqueness.