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Thursday, September 24, 2009

Remembering the Bad Along With the Good

In my Sept. 15, blog I surveyed an experiment that showed people learning more from their successes than from their failures. In so doing, I raised the possibility that the learning gain was promoted by the release of the "reward transmitter," dopamine. Now I find a new research report on the effect of dopamine on the long-term storage of bad memories. The process studied was the long-term memory of fear and pain. Rats were trained to remember a strong foot shock, which lasted at least 14 days. Injecting a dopamine blocker into the hippocampus erased the long-term memory if given 12 hours after the original foot-shock experience. This suggests that the normal release of dopamine can promote memory, which is not surprising since dopamine promotes the formation of proteins used in synaptic junctions of neurons.

However, foot shock is certainly not rewarding and probably does not release dopamine. But the end of the foot shock pain is a rewarding relief. Also, rewarding things do happen even to rats after a nasty foot shock (like sex with mates, eating, drinking, sleeping, etc.). The ongoing release of dopamine in the course of just living may help rats form lasting memories, regardless of the nature of memory. This raises questions that scientists have not studied yet. But it may be that dopamine helps us remember both the good and the bad. And maybe is one reason why bad memories are hard to erase.

Source: Rossato, J. et al. 2009. Dopamine controls persistence of long-term memory storage. Science. 325: 1017-1020.

1 comment:

  1. Ever since I went to university and had to get the content of thousands of pages into my head. But I wouldn't compare myself with rats. Aside of this, rats are very intelligent. Do they need a better memory? Just a little joke.
    I actually would be interested to hear from you, what you think about brain entrainment programs and about subliminals which work with certain frequencies.
    You can download a sample, to "hear" what I mean:
    I listen to this for a few day and suddenly do things more effectively. What surprises me is that I need one hour less sleep. (God, I need this time. One hour more each day.)

    Thank you for your blog Dr.

    Christa Herog
    (PhD in economics = Dr. of the financial world, which does not look good! Well, I am not practicing.)


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