New York, Nov 10 (IANS) Researchers have identified a gene -- previously known only to regulate bone growth and muscle metabolism in mammals -- that can also act as a promoter of brain maturation, cognition and learning in human and non-human primates.

The findings showed that osteocrin -- a gene found in the skeletal muscles of all mammals -- is completely turned off in rodent brains yet highly active in the brains of non-human primates and humans.

However, the activity of the gene was most intense in neurons of the neocortex, the topmost layer of cells covering the brain and responsible for higher-level cognition, such as long-term memory, thought and language. 

At the same time, osteocrin was noticeably absent from other parts of the brain responsible for non-cognitive functions such as spatial navigation, balance, breathing, heart rate and temperature control.

This suggests a possible role of the gene in the development of cognition -- a cardinal feature that distinguishes the brains of human and non-human primates from those of other mammals, the researchers said.

"We have uncovered what we believe is a critical clue into the evolution of the human brain, one that gives us a glimpse into the genetic mechanisms that may account for differences in cognition between mice and humans," said Michael Greenberg, Professor at the Harvard Medical School, in Boston, US.

Further analysis revealed that osteocrin's activation curbed the growth of neuronal dendrites -- branchlike projections responsible for transmitting signals from one brain cell to the next.

"Restricting dendritic growth is a precision-enhancing mechanism, essential to ensuring that neuronal wires don't get crossed and compromise signal transmission from one cell to the next," added Bulent Ataman, neurobiologist at the Harvard Medical School.

This observation suggests that osteocrin's activity may help enhance nerve cell agility and proper signal transmission to ensure robust communication across neurons, Ataman said.

For their experiments, published in the journal Nature, the team analysed RNA levels -- the molecular footprints of gene activity -- in the brain cells of mice, rats and humans.