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This Week in PNAS: Jun 18, 2014

Researchers from the US, Germany, Australia, and Peru included mitochondrial DNA sequence data in their analysis of pre-Columbian population patterns in Peru. The team sequenced hyper-variable 1 regions in mtDNA from more than 200 ancient individuals from southern Peru. Together with existing mtDNA data, the sequences suggested that at least two large migrations and related cultural shifts occurred in the region. The first involved movement from coastal valleys to the Andean highlands during a period around the year 640 that was marked by highly variable climate patterns, followed by a subsequent migration back to the coast nearly 600 years later.

Interactions between parts of the human brain involved in working memory and other processes rely on contributions from genes found in synaptic plasticity and neurodevelopmental pathways, according to findings from a German team. Through a gene set analysis of genotyping and brain imaging data for 269 healthy volunteers, the researchers looked for genetic contributors to interactions between the dorsolateral prefrontal cortex and the hippocampus in the brain. The search led to genes known for their roles in development, synapse formation, and organization, including genes tied to increased schizophrenia risk.

A team from the US and Singapore turned to computational approach to consider the role that dopamine genes play in strategic decision-making processes and interactions in a game theory context. With a gene set analysis approach, the researchers evaluated the apparent consequences of dopamine gene variation on 218 individuals' behaviors in a competitive game setting, identifying genes with apparent ties to features such as learning rate and belief learning. "We found that genes differentially expressed in separate brain regions influenced distinct components of people's decision-making processes," the study's authors wrote, "and that a surprising degree of consistency exists with what is known at the brain level about how people make decisions in social interactions."