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Comprehensive transcriptome analysis of neocortical layers in humans, chimpanzees and macaques
Zhisong He1, Dingding Han1,2, Olga Efimova3
1CAS Key Laboratory of Computational Biology, CAS-MPG Partner Institute for Computational Biology, SIBS, CAS, Shanghai, China.
Nature Neuroscience
|April 18, 2017
Summary
Human brain evolution shows accelerated cortical reorganization. Gene expression in cortical layers significantly changed in humans compared to chimpanzees, impacting over 5% of the transcriptome.
Area of Science:
- Neuroscience
- Evolutionary Biology
- Genomics
Background:
- Human cognitive uniqueness is evident, but the underlying brain changes are not fully understood.
- Comparative analysis of brain organization across species is crucial for understanding human evolution.
Purpose of the Study:
- To characterize and compare the transcriptomes of cortical layers in humans, chimpanzees, and rhesus macaques.
- To identify species-specific gene expression changes in the prefrontal cortex.
Main Methods:
- RNA sequencing of prefrontal cortex cortical layers and adjacent white matter.
- Unsupervised sectioning for precise layer isolation.
- Immunohistochemistry to validate gene expression changes in different cell types.
Main Results:
- Over 20% of detected genes showed layer-specific expression, defining 2,320 human layer markers.
- 376 layer-specific genes (16% of human markers) switched expression in the human lineage, compared to 133 in chimpanzees.
- Human-specific expression changes were observed across various cortical cell types, not just neurons.
Conclusions:
- Human neocortical organization has undergone significant transcriptomic changes, with accelerated reorganization on the human evolutionary path.
- These changes affect over 5% of the human prefrontal cortex transcriptome, despite apparent histological conservation.
- The findings highlight substantial molecular evolution in the human brain beyond simple expansion.