August 23, 2012

Increased complexity in certain regions sets apart human and chimp brains

Frontal lobe (CC-BY-SA-2.1-jp)
This paper looks like a very important research piece for the understanding of the human mind, of what makes our brains specifically human and ultimately of what makes ourselves what we are.

Genevieve Konopka et al., Human-Specific Transcriptional Networks in the Brain. Neuron 2012. (Freely accessible apparently) ··> LINK [doi:10.1016/j.neuron.2012.05.034]


Understanding human-specific patterns of brain gene expression and regulation can provide key insights into human brain evolution and speciation. Here, we use next-generation sequencing, and Illumina and Affymetrix microarray platforms, to compare the transcriptome of human, chimpanzee, and macaque telencephalon. Our analysis reveals a predominance of genes differentially expressed within human frontal lobe and a striking increase in transcriptional complexity specific to the human lineage in the frontal lobe. In contrast, caudate nucleus gene expression is highly conserved. We also identify gene coexpression signatures related to either neuronal processes or neuropsychiatric diseases, including a human-specific module with CLOCK as its hub gene and another module enriched for neuronal morphological processes and genes coexpressed with FOXP2, a gene important for language evolution. These data demonstrate that transcriptional networks have undergone evolutionary remodeling even within a given brain region, providing a window through which to view the foundation of uniquely human cognitive capacities.

Hippocampus (CC-BY-SA-2.1-jp)
For what I could understand, mostly from the press release, the authors unveiled increased complexity of the gene expression modulating three regions of our brains: the frontal cortex, the hippocampus and the striatum.

It is not a mere matter of size but specially one of much increased complexity in the wiring of these three regions what seems to make our brains unique. 

The research also reinforces the apparent importance of the much debated genes CLOCK (affecting circadian rhythms, mood, pregnancy and metabolism), FOXP1 and FOXP2 (related specially with speech), whose connectivity is much increased in humans in comparison with our ape cousins.

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