Social hierarchy prewired in the brain

September 30, 2011 by Deborah Braconnier, Medical Xpress report
Modern human brain
Modern human brain. Image source: Univ. of Wisconsin-Madison Brain Collection.

(PhysOrg.com) -- If you find yourself more of a follower than a social leader, it may something to do with the wiring in your brain. According to a new study in Science, researchers from the Chinese Academy of Science have discovered a location in the brain that is active in alpha mice but not in their subordinate cage mates.

The researchers, led by Hailan Hu from the Chinese Institute of Neuroscience, discovered that in social dominant mice, there were stronger electrical connections occurring in the , or mPFC, of the brain. This study was designed to test just what impact this activity had on social ranking.

To begin, the researchers had to determine which mice were the social dominant mice. Using a clear two, a mouse was placed at either end. The more dominant mouse would push through to get to the other end while the subordinate mouse would retreat.

Once the subordinate mice were determined, the researchers injected them with a virus that inserts the gene GluR4 into the mPFC . The role of GluR4 is to amplify the electrical signals. The tube test was then repeated. These previously timid mice that retreated in the tube were now the dominant mice and pushed forward. In looking at brain slices from the mice, the researchers noted that the mice that received this virus now had almost twice as strong as the control mice.

In another test, the researchers injected the dominate mice with another virus that implanted the R4Ct gene which reduces electrical transmissions. This gene reduced the neuron connections by 71% of those found in . When the were reduced, these previously dominate mice were now subordinate.

While this shows a role in social standing in mice, Hu cautions that in humans it is a much more complex relationship. Where social standing in mice is more relative to temperament, human social ranking is also influenced by outside factors such as wealth, heritage and education.

Explore further: Your brain on nicotine: Nicotine receptors affect social behavior

More information: Bidirectional Control of Social Hierarchy by Synaptic Efficacy in Medial Prefrontal Cortex, Science DOI:10.1126/science.1209951. www.sciencemag.org/content/ear … 9/28/science.1209951

ABSTRACT
Dominance hierarchy profoundly impacts animals’ survival, health, and reproductive success, but its neural circuit mechanism is virtually unknown. We found that dominance ranking in mice is transitive, relatively stable, and highly correlates among multiple behavior measures. Recording from layer V pyramidal neurons of the medial prefrontal cortex (mPFC) showed higher strength of excitatory synaptic inputs in mice with higher ranking, as compared with their subordinate cage mates. Furthermore, molecular manipulations that resulted in an increase and decrease in the synaptic efficacy in dorsal mPFC neurons caused an upward and downward movement in the social rank, respectively. These results provide direct evidence for mPFC’s involvement in social hierarchy and suggest that social rank is plastic and can be tuned by altering synaptic strength in mPFC pyramidal cells.

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4 comments

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hush1
3.7 / 5 (3) Sep 30, 2011
"Using a clear two..." - Deborah Braconnier


The article wants me to submit reading the word "two".

After injecting the virus that inserts the gene GluG4 into my mPFC neurons to amplify my electric signals I no longer submit to the word "two".

With my new found dominance I assert over readers and writer and make them submit to the word "tube".

I am told there is a complex relationship between reader, writer and spell checkers.
A_Paradox
5 / 5 (2) Oct 01, 2011
hush1, :-)
can you tell us how to get hold of this virus please. The complex relationship between Australian readers and American spell checkers is often marred by the ruthless assertion of dominance by the latter. I suspect the same baleful influence blights the lives of the Brits too. For Aussies, two and tube have a different vowel sound; two has a plain "oo" sound, but tube is t you b ie a diphthong.

I am a bit perplexed by how a spell checker could bully a writer into choosing "two" instead of "tube", but maybe the American spell checker has been authorised to include suggestions based on "sound-alike" criteria.Maybe she was typing it up late at night and therefore tired and sleepy so the spell checker could use hypnosis rather than skulduggery or even naked violence.
rsklyar
1 / 5 (2) Oct 03, 2011
Plagiarism in a "family" style
How young ambitious capoes and soldiers from Italian Institute of Technology (IIT) under supervision of a decrepit american don-godfather from Northwestern University are successfully completed their sequential plagiaristic enterprise: http://issuu.com/...saivaldi
Ethelred
5 / 5 (2) Oct 04, 2011
He published before according to your link.

So why are you spamming the hell out of this site with what your own link shows is a false accusation.

I hit five of his posts this way. I think that enough he has dozens of identical posts and his own link shows his accusations are false.

Ethelred

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