Showing posts with label fMRI. Show all posts
Showing posts with label fMRI. Show all posts

A Random Income Game?


Social scientists and psychologists love to have us playing economic games. They usually give us lots of opportunity to look after our own interests. With games like the ‘Prisoner’s Dilemma’ we set ourselves against an individual, but in the ‘Random Income Game,’ RIG, we play in a group although we make the decisions individually.

The RIG has a group who are randomly assigned an income, but the distribution may be varied.  As group members can see what their colleagues are getting, the may opt to even things up. With multiple rounds, group composition changes so a bad reputation doesn’t stick.

Dawes et al have got a group to play the RIG while sticking their heads in the big magnet to get fMRI scans of which parts of their brains are working when they are making the decisions (1,2). The subjects showed an admirable tendency towards an egalitarian distribution of wealth. They also had some questions to answer that were aimed at their thoughts on society and how they would split cash with someone else.

All this allowed the researchers to focus down on the insular cortex as being the seat of egalitarianism. The insular cortex is thought to be where we are self-aware and where we judge levels of pain. But, importantly in the context of this study, it is where our feelings of empathy arise.

As the US presidential campaign starts to get into serious mode we are due to hear a lot about fairness and taxes and one can hope that there will be a lot of insular cortex activity with both the candidates and the voters by November.

  1. http://www.sciencedaily.com/releases/2012/04/120409164307.htm
  2. http://www.pnas.org/content/early/2012/04/05/1118653109.abstract



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Amazing Drives


In many social animal species, we see cooperation. Often those cooperating are related. Humans are among the species that cooperate effectively without being related. One of the current ideas is that this is learned over a long period and is based on the idea that we discern other to have thoughts and feelings similar to ours, which makes that cooperation work.

With a big magnet free, the big question can be asked what parts of the brain are working hard when we cooperate. Krill and colleagues gave 28 participants driving tests while having fMRI scans of their brains and reported on their results in the Public Library of Science (1).

The driving was through a maze on a computer screen. No easy task as they had a time limit to drive through each maze and they were presented with multiple mazes. It may be hard enough trying to drive through a maze when getting an fMRI, but this was just the baseline.

The real challenge was putting the participants in pairs and blindfolding the driver. The other person acted as instructor, indicating right, left, accelerate or brake NOW! They then changed places so that the other could shout at the driver.

After all this excitement the pictures were analyzed. Lots of brain activity of course. Now comes the really exciting part. Each person’s baseline image was subtracted from their blind driving images and there was consistently more activity in two regions when people were cooperating.

The regions were the orbital frontal cortex, and the caudate nucleus, right in the center of the brain. This part is associated with learning and feedback processes, but is also loaded with dopamine neurons. This means that there is a reward feeling (we like dopamine hitting our receptors) when we’re cooperating.

So it appears that we’re hard wired to cooperate with each other. It is interesting that the participants, who were 24 – 25-years old, were made up of 18 women and 10 men. However, the make-up of the pairs wasn’t given in the paper, so we don’t know if things would work better or worse if a blindfolded male was paired with a female instructor or vice versa. We are left to our prejudices remembering that men are notorious for not stopping to ask directions when lost.


  1. http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0030613



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How Will You Stack Up When The Chips Are Down?


When we are pushing ourselves hard, our oxygen demand gets high, we get out of breath and we (most of us) stop to catch our breath before returning to the competition, battle or whatever the devilish physiologists are throwing at us this time.

Top class athletes, apart from being better at their sport than the rest of us, will push themselves harder. It is the old saw about when the going gets tough, the tough get going, supposedly. So what is it about their brain activity that gives them that edge?

Paulus et al have made a start at sorting this out in a recent experimental study (1). Their lab rats consisted of 10 world class adventure racers who combine orienteering with severe cross country running at the elite level. Both men and women were selected and their average age was 37.5. A similar size, mixed gender control group were selected from healthy individuals with an average age of 36.6.

The participants lay with their head in the big magnet for fMRI studies while their breathing was restricted. They had to breath through a hose with sintered bronze filters. This would put a similar mental load as extreme exercise, without the pain in the legs, of course. However, to challenge the brain/body coordination, the participants had to play a computer game of pressing a button in repose to things happening on a screen.

The result of all the hard work is that the right insula of the elite athletes activity was less than with the control subjects. The significance is that effects of emotions like fear and awareness of risk were lower, or suppressed with the elite athletes.

We use this side of the brain for approximate estimations and working on novel situations. It appears that attenuation of the activity might mean less imagination, and thus not imagining the bad results of pushing oneself to the limits. My imagination encourages me to stop for a cup of tea and sympathy when things get too hard and, I suspect, I'm in the majority.

  1. http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0029394



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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