Are new neurons born in the adult human brain? Study revives debate, Pg2

Key Highlights:

• A new study published in Science reports evidence of neural progenitor cells and young neurons in the hippocampus of adult human brains, reviving the debate on neurogenesis in adulthood.
• The study used single nuclei RNA sequencing to analyze over 400,000 neurons from the hippocampal region of post-mortem brain samples, identifying intermediate neuronal stages even in adolescent and adult brains.
• Researchers at the Karolinska Institutet in Stockholm identified neural stem cells, neural progenitors, and neuroblasts using a machine learning algorithm.
• Experts agree that methodological differences are the root cause of discrepancies across different studies.

Detailed Insights:

• The 1998 study provided the first direct evidence that new neurons could be generated in the hippocampus in adults, suggesting a regenerative potential in the adult brain.
• Studies have shown that neurogenesis occurs in the adult brains of mice, rats, and even monkeys, and identified several critical functions of adult-born neurons in the hippocampus.
• The new study used single nuclei RNA sequencing, providing a near-complete signature of genes that are expressed in each cell, allowing the team to monitor hundreds of markers in cells simultaneously.
• Some experts remain skeptical, arguing that detecting RNA alone doesn’t prove that a gene is actively producing a functional protein, and that antibody-based staining methods would have been more convincing.
• Adult neurogenesis is important in the hippocampus because it can explain how the hippocampus can perform critical memory-related functions.
• Encouraging locally present neural progenitor cells to produce the neurons that are needed is easier than transplanting externally differentiated stem cells, which can be an invasive and risky procedure.

Scientific/Technical Concepts Involved:

• Neurogenesis: The process by which new neurons are formed in the brain.
• Hippocampus: A region of the brain primarily associated with memory and spatial navigation.
• Neural Progenitor Cells: Cells that can differentiate into various types of brain cells, including neurons and glial cells.
• Single nuclei RNA sequencing: A technique used to analyze the RNA content of individual cell nuclei, providing insights into gene expression patterns.