Interhemispheric gene expression differences in the cerebral cortex of humans and macaque monkeys

Area of Science:

• Neuroscience
• Genetics
• Comparative Biology

Background:

• Handedness and language are key examples of human brain lateralization.
• While genetic models exist, hemisphere-specific gene expression differences in humans are not fully understood.
• Understanding these differences is crucial for comprehending brain asymmetry.

Purpose of the Study:

• To investigate gene expression profiles in homologous cortical regions between human and macaque brains.
• To identify hemisphere-specific gene expression patterns related to handedness and language.
• To explore differences in gene co-expression modules between cerebral hemispheres.

Main Methods:

• Examined gene expression profiles in ventrolateral prefrontal cortex, posterior superior temporal cortex (STC), and primary motor cortex.
• Compared gene expression in both hemispheres of humans and rhesus macaques.
• Utilized weighted gene correlation network analysis to identify co-expression modules.

Main Results:

• Overall gene expression patterns were highly similar between hemispheres in both species.
• Weighted gene correlation network analysis identified hemisphere-associated gene co-expression modules.
• A specific receptor-enriched gene module in the STC showed differential expression between hemispheres exclusively in humans.

Conclusions:

• Hemispheric gene expression is largely conserved between humans and macaques.
• Specific gene modules, particularly in the STC, exhibit human-specific hemispheric differences.
• These findings provide insights into the genetic underpinnings of human brain lateralization for functions like language.