Extroverts In The Big Magnet

In yesterday’s post, we saw that London cab drivers had increased the amount of gray matter in the rear section of the frontal lobes of their brains by stuffing them full of the details of the sights, sites and streets of central London. Well, the amount of gray matter in the frontal lobes has other effects too.

The reason that I bring this up is that the classic London cab driver was always chatty and a fund of information. A touch of the extrovert, perhaps. Personally, I’ve experienced some quite extroverted driving when being late for a train, which included a U-turn in crowded traffic and then the cab taking to the sidewalk to get past a local log-jam. The excitement increased the size of the tip, of course.
Coming to our aid today, Cremers et al from the Netherlands have put another 65 healthy people into the big magnet and reported out in the Public Library of Science (1). We should note that these weren’t cab drivers from London, or elsewhere, but just representing a typical cross-section of people.

Jumping straight to the results, it was found that those with larger volumes of their right amygdalas and orbitofrontal lobes (the bits behind the forehead and eyes) were extroverts. The more gray matter, the more extroverted. Recall that the OFC does the job of controlling your reward and emotional behavior. Thus, it is also involved in your decision making.

A bigger amydala goes along with larger social networks, good news, but can also be related to binge drinking. It also was an indicator for sexual extroversion in men, although it had the opposite trend with women.

If sending guys out to learn the streets of central London beefs up their hippocampi, maybe it could be doing the same for their OFCs and amygdalas. Extroverts are much less likely to suffer from depression. Do you suppose that a cure might be found wandering around the backstreets of central London until “The Knowledge” is firmly grasped? We need to get this Dutch team looking at the fMRI pictures from yesterday’s study of London cabbies.

  1. http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0028421

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