Brain Evolution and Uniqueness in the Human Genome

Non-coding RNAs: Lost in translation?

“…In this article, the authors scanned the human genome and found out that this cluster of anti-sense ncRNAs displays a significant accelerated nucleotide substitution rate in humans, indicating that they may be important for human brain function. Furthermore, two commentaries, one in Nature (Ponting & Lunter, 2006) and the other in Cell (Amadio & Walsh, 2006), extensively associated the importance of these findings with brain complexity. This reinforces the idea that ncRNAs may have an important role in shaping complex traits in higher organisms.…”

Eukaryotic regulatory RNAs: an answer to the ‘genome complexity’ conundrum

“…Interestingly, the HAR1 region is transcribed as part of two overlapping ncRNA genes, HAR1F and HAR1R, and lacks homology with any known ncRNA genes (Pollard et al 2006). The human HAR1F RNA adopts a unique structural confirmation appreciably distinct from the HAR1F RNA of human/chimpanzee ancestors (Amadio and Walsh 2006;Pollard et al 2006). Human embryonic brain sections showed strong expression of only HAR1F and not HAR1R, between 7 and 19 wk of gestation-a critical period for cortical neuron migration and fate specification.…”

“…Previous studies to elucidate genome evolution across species mostly concentrated on processes that result in either addition or deletion of genes or on changes in amino acid sequences Nielsen et al 2005). However, recent studies have appreciated the importance of noncoding segments in the genome (regulatory elements, splicing signals, and ncRNA genes) in various aspects of species evolution (Amadio and Walsh 2006). Recently, Haussler and colleagues (Pollard et al 2006) have undertaken a genome-wide scan for regions highly conserved across mammalian genomes that appear to have undergone a sudden and rapid evolution in the human lineage, and their studies suggest the involvement of ncRNA genes in shaping human brain evolution (Pollard et al 2006).…”

Is this a brain which I see before me? Modeling human neural development with pluripotent stem cells

“…This has led to the enlargement of the surface and thickness of the cortex, associated with relative expansion and diversification of certain cortical areas, more profound cortical lateralization, and expansion of the uppermost layers (Amadio and Walsh, 2006;Rakic, 2009). From a more cellular viewpoint, comparison of the cortex from human and non-human primate species has revealed increased number and diversity of human cortical neurons (Bystron et al, 2006;Hill and Walsh, 2005;Nimchinsky et al, 1999;Roth and Dicke, 2005) and distinct patterns of neuronal morphology, such as increased size and density of dendritic spines in some areas (Benavides-Piccione et al, 2002).…”