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Mar 26

Our modern world is complex and constantly changing - do you have the ability to change your behavior in our ever faster changing world?

We all make mistakes, the question is can you learn from your mistakes. At the gene level can a polymorphism of a gene affect our ability to learn when things change? Sometimes in life a tried and true behavioral response stops working - the question is how quickly do you realize that the old way is not working, and you change your behavior to the new reality.

In the labs researchers study the ability of humans to adapt to a changing environment by using a reversal learning task. After the subjects have learned a task by responding to a stimulus in a certain fashion for a reward (on a probabilistic level in the paper under discussion) the researchers suddenly change the rules and what you did previously for reward is no longer rewarded (at a probabilistic level). What do you do? The environment has changed, how long does it take you to learn the changing environment? This is the general basis of reversal learning.


Jocham et al., 2009 studied the reversal learning ability in 28 subjects young health subjects (20-32). The variable the researchers were wondering about was the dopamine D2 receptor. This receptor in humans has a number of polymorphism, but the particular one being studied is called the A1 allele which is associated with a reduction in the number of receptors in the striatum (approximately 30% reduction).

If the subjects have the A1 allele (less D2 receptor expression) they are designated at A1+

Behavioral results:

The subjects underwent a probabilistic reversal learning task that consisted of a total of 18 reversals - in which the subjects had to realize (learn) the rules had changed and adjust their behavioral choice.

The overall amount of reward obtained by the two groups (A1+ vs A1-) did not differ, nor did the number of reversal errors. However, when analyzing the 8 trials after a final reversal error the percentage of trials in which the subjects maintained the correct response before switching back to the now incorrect response is reported in the figure below.

As you can see from the above the graph the subjects with the A1+ allele were more likely to be incorrect - by switching back to old previous response. Or you could say the A1- subjects were more persistence in maintaining the new found rules. The authors point out the A1+ subjects in general switched back and forth between the two choices compared to the A1- group (what would the A1+ group do with many more choices?).

Imaging of the brain:

When there is a reversal of the rules the subjects are no longer rewarded for their previous response and this is considered negative feedback. Based on the subjects current understanding of the rules they were expecting to be rewarded for their correct response - but if the rules had changed there was no reward and hence negative feedback. The researchers scanned the subjects (fMRI) while doing the reversal learning task.

The graded increase of response to negative feedback observed in the rostral cingulate zone was less in the A1+ group as compared to the the A1- group. Additionally, the A1+ subjects had less left ventral striatum and right lateral orbitofrontal cortex activation.

Authors’ conclusions:

…our results demonstrate that a genetically driven
reduction in striatal D2 receptors affects performance in a probabilistic
reversal learning task. The behavioral alteration did not
consist of increased perseverative errors. Rather, A1+ subjects,
having reduced D2 receptor density compared with A1- subjects,
had difficulty in maintaining the newly rewarded response
after behavioral adaptation in response to a change in task rule
Moreover, these subjects were in general more likely to switch
back and forth between the response alternatives
. In particular,
A1+ subjects frequently switched to the other response although
they had just been reinforced for the response they made
. These
subtle behavioral differences were accompanied by changes in
feedback-related BOLD signals.

So what, you might be asking?

Good question. Well maybe you are one of those with the A1+ polymorphism.

Previous research indicate that A1+ subjects have a reduced capacity to learn from negative feedback (Klein et al., 2007), and when combined with the paper under discussion it suggest the D2 receptor may play a role in feedback learning in general.

15-21 % of the north American population (European origin) have the A1+ polymorphism (Kidd et al., 1996). This polymorphisms, which results in a reduction in D2 dopamine receptor, has already been linked with pathological gambling (Comings et al., 1996), addiction (for review see: Foll et al., 2009), and obesity (Stice et al., 2008). All of these three you could say at one level or another is related to reduced ability to learn from negative feedback, or feedback in general.

More so, beyond your genes there are various external factors that decrease or increase your D2 receptor levels.

You can make certain real life choices that increase your D2 expression, or other choices that decrease your D2 levels. If you had a choice which way would you want to go - reduced learning ability or increased ?

Keep coming back and I will tell you the brain hack to increased your D2 receptor expression.

4 Responses

  1. Encephalon 68: A carnival of neuroscience « Ouroboros Says:

    [...] A:More broadly, how do we use experience of the past to adapt to a changing environment? At Brain Health Hacks, Ward Plunet describes a study of the effect of a dopamine receptor polymorphism on learning [...]

  2. Troy Says:

    So, I keep coming back but haven’t seen a post yet on how to D2 receptor expression! :)

  3. Ward Says:


    thanks for the comment, and the reminder :) I promise that I will post something on how to increase D2 receptor expression on Monday.

  4. Troy Says:

    That’s great. See, I really need that information as I forgot the word “increase” in my comment to you! :) Look forward to it Monday. You know when you search this stuff online, there’s much info on how to increase dopamine, but nothing on hacks to increase the receptors, which seems to me the greater point.

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