Genes associated with cognitive ability and HAR show overlapping expression patterns in human cortical neuron types

Area of Science:

• Neuroscience
• Genetics
• Human Evolution

Background:

• Genome-Wide Association Studies (GWAS) have identified numerous genes associated with human cognition.
• The cell type-specific expression profiles of these cognition-associated genes in the human brain remain largely unknown.
• These genes overlap with Human Accelerated Regions (HARs), which are implicated in human brain evolution.

Purpose of the Study:

• To investigate the expression of cognition-associated genes in adult human cortical neurons.
• To determine the relationship between the expression of these genes and neuronal function and structure.
• To explore the role of these genes in human brain evolution and cognitive abilities.

Main Methods:

• Analysis of gene expression profiles in adult human cortical neurons.
• Correlation analysis between gene expression levels and neuronal properties such as total dendritic length (TDL) and action potential (AP) kinetics.
• Identification of genes associated with TDL or AP kinetics and their functional enrichment.

Main Results:

• Cognition-associated genes are preferentially expressed in Layer 3 (L3) pyramidal neurons in the middle temporal gyrus (MTG).
• Neurons exhibiting higher expression of these genes showed significantly larger total dendritic length (TDL) and faster action potential (AP) kinetics.
• A subset of genes linked to TDL or AP kinetics were identified, characterized by predominantly synaptic functions and a high abundance of HARs.

Conclusions:

• The study reveals specific neuronal expression patterns for genes linked to human cognition.
• Neuronal expression of these genes is associated with structural and functional properties (TDL, AP kinetics) previously correlated with intelligence.
• These findings suggest a potential role for HAR-rich genes in synaptic functions, neuronal structure, and human cognitive evolution.