In The Mood To Tweet?


From time to time we feel happier than at other times depending on the up and downs in our individual lives. But some of those up and downs are shared with large sections of the population and depend on the politicians and financial conjurors that we have in place. These days we let off steam with Tweets to all our cyber friends. The twittering increases daily.

Dodds et al have been doing a lot of listening lately (1). They’ve kept their ears to the ground for a period of 3 years, listening to 63 million of us tweeters. Of course, they didn’t sit at their computer screens for this epic adventure. They used their computers to do the job for them and they analyzed the Tweets for words that indicated the degree of happiness of those that were Twittering.

This was no mean feat as they used a database of 10,000 individually graded words, but it meant that they were able to monitor the degree of happiness of the population that they were sampling. The study period was from September, 2008 to August this year.

Happiness spiked on notable days like Valentine’s Day, Easter, New Year’s Eve, Christmas and Independence Day, but there was a slight trend up during 2008, followed by a fairly level period until a decline over the past year. Not a surprise to most of us.

The TGI Friday feeling is alive and well. There was a weekly peak in the average happiness rating on Fridays and Saturdays. Sundays was already diving down towards the Monday level.

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0026752



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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

Building The Knowledge


London Taxi Photo: David Iliff, License: CC-BY-SA 3.0


The classic source of information for a newcomer in any major city was the taxi driver. Usually they knew their city in detail and would drive you around the important features, (for a fee of course,) while educating you in the politics and the comings and goings of the important and beautiful people of the place. Now the GPS has replaced that detailed mental map and you get more politics and gossip than education.

London, though, is hanging on to tradition. GPS units are not for the London cabbie who needs to find short cuts to dodge the usual traffic jams. The cabbie’s job needs more brain than can be found in a little box of electronics. Flexibility and instant decisions are required in addition to the map.

To get a Hackney Cab License in the City of London, a potential cab driver has to study hard to acquire “The Knowledge”. It can take about four years to pack the details of 320 routes around Charing Cross into one's brain. Details, details and more details have to be instantly recalled. How many of us could instantly recall any one of 25,000 different streets let alone not fail to mention one of 20,000 landmarks when asked.

That’s a lot of “Knowledge” to stuff into anyone’s head and Woollett and Maguire of U College have followed the stuffing process with 79 prospective London cabbies. Of course, the big magnet was rolled out and fMRI scans were done over the four-year training period (along with controls of course).

Some of the candidates showed increasing gray matter building up in the front part of their brains, their posterior hippocampi to be exact.  These guys passed the test and got their licenses. The ones whose brains didn’t change failed and are now going by bus.

It is interesting to note that their heads didn’t get bigger to accommodate the fresh gray matter. It appears that the failing potential cabbies were able to do better on complex visual memory tasks than the passing ones. So it seems that the spatial memory required for  “The Knowledge” takes up a lot of space and crowds out other functions. All part of the price for getting a license to drive the rich and famous as well as you or I, I suppose. 
  1. http://www.bbc.co.uk/news/health-16086233
  2. K. Woollett & E.A.Maguire, J. Curr. Biol, (2011), doi: 10.1016/j.cub.2011.11.018