Extended synaptic development may explain our cognitive edge over other primates

Over the first few years of life, human cognition continues to develop, soaking up information and experiences from the environment and far surpassing the abilities of even our nearest primate relatives. In a study published online today in Genome Research, researchers have identified extended synaptic development in the human brain relative to other primates, a finding that sheds new light on the biology and evolution of human cognition.

"Why can we absorb environmental information during infancy and childhood and develop intellectual skills that chimpanzees cannot?" asks Dr. Philipp Khaitovich of the Chinese Academy of Sciences and the Institute for Evolutionary Anthropology, senior author of the report. "What makes the human brain so special?"

Chimps diverged from the human lineage about 4-6 million years ago, a relatively short period of time by evolutionary standards. Yet the differences in specialized social and cultural cognitive skills between humans and chimps are striking, and much remains unknown about the biological basis.

To answer his questions, Khaitovich and an international team of researchers used microarray and RNA-sequencing technology to investigate changes in how genes are read, or expressed, during development of the postnatal brain in humans, chimps, and macaques, a more distantly related primate. And the timing of these changes may set human cognitive development apart from other primates. The group sampled the prefrontal cortex, a more recently evolved brain region associated with cognition, and the cerebellum, an ancient brain region related to motor control.

Khaitovich explained that of the human brain often produce murky results, however this approach performed even better than expected, pointing them to a specific postnatal developmental process. "Among all developmental changes specific to the human brain, one process – synaptogenesis – clearly stood out." Khaitovich explained that synaptogenesis, the foundation of learning and memory in the developing brain, is characterized by the formation of synaptic connections, strengthening useful connections, and also elimination of useless connections.

The authors found that in humans, peak expression of synaptic genes in the prefrontal cortex is delayed until about age five, in contrast to chimps and macaques where this occurs in the first year of life. The authors noted that this human-specific change was only observed in the , and not in the cerebellum

"Our findings suggest that the remains extremely plastic and susceptible to environmental input during the first five years of life," said Khaitovich. "Our study uncovers one of the important mechanisms potentially involved in evolution of ."

More information: Liu X, Somel M,Tang L, Yan Z, Jiang X, Guo S, Yuan Y, He L, Oleksiak A, Zhang Y, Li N, Hu Y, Chen W, Qiu Z, Pääbo S, Khaitovich P. Extension of cortical synaptic development distinguishes humans from chimpanzees and macaques. Genome Res doi: 10.1101/gr.127324.111

Related Stories

Like humans, chimps are born with immature forebrains

Aug 11, 2011

In both chimpanzees and humans, portions of the brain that are critical for complex cognitive functions, including decision-making, self-awareness and creativity, are immature at birth. But there are important differences, ...

Human cerebellum, cortex age in different ways

Aug 02, 2005

Researchers have found that the two primary areas of the human brain appear to age in radically different ways. The cortex used in higher-level thought undergoes more extensive changes with age than the cerebellum, which ...

Recommended for you

New research software automates DNA analysis

Oct 20, 2014

At the core of medical research is problem-solving, which is exactly what two PhD scientists did when they set out to eliminate a common, time-consuming task performed in research laboratories around the world.

User comments

Adjust slider to filter visible comments by rank

Display comments: newest first

HenisDov
1 / 5 (4) Feb 04, 2012
Way back...

http://universe-l...rsity-2/

Dov Henis