DOMINANT mice can be humbled and wimps made mighty by altering the strength of electrical connections in their brain. The work may reveal mechanisms that dictate social standing in people.
Crucial brain connections directing a mouse’s place in the social hierarchy sit in the medial prefrontal cortex. To investigate the mPFC’s role in social ranking, Hailan Hu of the Chinese Institute of Neuroscience in Shanghai and colleagues first worked out the hierarchy within a group of mice through challenges between pairs in tubes. When the mice came face to face, the subordinate animal would back out of the tube.
The team then injected a virus into some of the mice that inserts a gene into mPFC neurons. The gene amplifies transmission of electrical signals – a key step in strengthening connections.
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When the tests were repeated, previously subordinate mice that had received the virus became dominant. Likewise, implanting a gene that reduced the strength of connections caused previously dominant mice to become subordinate (Science, ).
Hu says that the strengthened connections probably enable mice to exert more control over anger, emotion and aggression.