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.

Why The Rich Get Richer

... (and the Smart Get Smarter)

This old saying also has a corollary: the poor get poorer (at least relative to the rich). Of course there are exceptions, but these correlations happen often enough to indicate there is some truth to the saying. I never heard anybody explain this, other than to conclude that life is just unfair. But there is an explanation.

The reason is that the rich learn from their successes, while the poor, who don’t have many successes, fail to learn from their failures. And the reason for that is that the human brain is wired to learn better from success than from failure. It all has to do with the positive reward system in the brain. Practically speaking, the most obvious example is how animals are trained for circus performances, how dogs are trained to sniff out drugs or corpses, and the like. Positive reinforcement when they do things right promotes learning more effectively and faster than punishing them when they do things wrong. Apparently, the same principle holds for people.

A report of a study of nerve cell activity in monkeys showed sustained, persistent outcome-related responses in both prefrontal cortex and in the basal ganglia, areas known to participate in learning stimulus-response associations. These neurons keep track of successes and failures over many seconds, which is long enough to form a semi-permanent memory that can affect the response the next time such a learning opportunity arises. The neural response improves after a recent success, but doesn’t improve as much after a recent failure. Not surprisingly, monkeys that were rewarded for the right resonse to a cue learned quickly how to respond the next time they saw the cue. But monkeys that responded incorrectly weren’t any better able to deal with the same cue the next time they saw it.

The authors speculate that successes are more informative than failures. When you fail, you typically already know why and there is not much new to learn. Why then do we keep making the same mistakes? I suspect that habit and emotional factors have a lot to do with it. Compulsive gambling and drug abuse are classic examples of repeatedly doing what you already know is wrong. I remember when I tried many times to quit smoking I only succeeded long term when I took up jogging, which is accompanied by the positive reinforcement of endorphins.

I also suspect that a major reason you learn more from success than from failure is the power of the brain’s dopaminergic and endorphin reward systems. Not only does positive reinforcement feel better emotionally than punishment, there is a real possibility that the dopamine release associated with reward has a direct biological influence on memory formation.

Source:
Histed, M. H., Pasupathy, A., and Miller, E. K. 2009. Learning substrates in the primate prefrontal cortex and striatum: sustained activity related to successful actions. Neuron. 63 (2): 244-253.

Motivation Comes In First

Laura, of "Dr. Laura" fame posted in her blog an item about how some students are paid money for doing well in school. Her blog referred to a Fox News item about a school district that was using financial rewards to motivate students to get good grades. ... Why would MONEY make the difference, and not the appreciation of their parents, the respect of their peers, the approval from their teachers, or the mere burst of pride in doing well? The answer is simple: kids these days are not raised to care about appreciation, respect, approval and pride…period! They are brought up to care about celebrity, extravagance, notoriety, freakish attention (think reality shows), infamy as a positive experience, and extreme non-conformity to traditional values. What happens to these kids when the money isn’t there, but there is still the expectation of profound effort and commitment? Certainly teachers, police, firefighters, those in the military, and small shop owners (to name just a few) aren’t putting out their best efforts for the financial reward. A police officer who “collars” a serious bad guy gets a lot of thumps on the back, a night of some beers with fellow colleagues, and a notch toward an eventual promotion in rank. Mostly, he has pride in doing his job well. ... Schools have been eliminating accolades such as high honors at graduation (e.g., valedictorian) so as not to hurt the self-esteem of those who won’t or can’t rise to that occasion. Yet, they want to give money, money, money to those who do. What is THAT message? No one’s feelings are going to be hurt because they didn’t get the money, money, money. Ugh."

I say "Ugh" too. At the heart of the school problem is that so many kids do not take pride in their work. How do you suppose that translates when they get out of school and on the job? I would argue that the most valuable lesson one can learn in school is to take pride in one's work. This story reminds us all that when it comes to learning, motivation may not be everything, but it is way ahead of whatever is in second place (which is probably poor memory skills). I have been teaching for almost 50 years, and I can tell you that positive motivation can overcome bad teachers, bad textbooks, boring subject matter, and almost any obstacle to learning you can think of. Conversely, no matter how hard a school or teacher may try to provide a good learning environment, good student performance is not going to happen without motivation. If people want to learn badly enough, they will surely find a way. True, a few academic subjects may be too advanced for a given level of IQ or pre-requisite learning. But even the slow of wit can learn a lot more than most people think. It may just take longer.

Source:Readin’, ‘Riting, and ….Bribing? June 11, 2009 on 10:32 am In Children, Education, Parenting, Values . Dr. Laura's Blog

Naps Promote Learning of Movement Skills

Whether you are learning to play the piano or learning to throw a football to a fast-breaking receiver, the necessary muscle movements have to be memorized. Converting the memory of movements into long-lasting form takes several hours or more for the brain to "consolidate" the learned movements. This process can be interrupted by trying to learn a different movement during this vulnerable period. For example, consolidation of the memory for a few chords on the piano can be disrupted by trying to learn finger movements on a computer keyboard during this vulnerable period.

Another feature of motor learning is that delayed gains in skill performance can occur after a latent period of several hours after an effective learning experience. This delayed performance gain depends on the first post-training night's sleep (I have explained the role of sleep on other kinds of memory in my book on improving memory).

Now comes a study that shows that daytime naps condense the time course of motor memory consolidation. In the experiment, subjects learned a five-element finger-to-thumb opposition sequence with their non-dominant hand. Then the experimenters tested the effect of a post-training nap. Compared to no-nap controls, a 90-minute daytime nap immediately after training markedly reduced the susceptibility to post-training interference effects and produced a much earlier expression of delayed gains within 8 hours post training. Thus, both memory-enhancing effects were produced by the nap.

Would a shorter nap produce the same effect? We don't know. It wasn't tested. Another untested possibility is that the daytime nap might enhance the memory consolidation that is normally produced by a night's sleep after a motor learning experience, especially if the task is rehearsed that same day after the nap.

Source:

Korman, M. et al. 2009. Daytime sleep condenses the time course of motor memory consolidation. Nature Neuroscience. 10 (9): 1206-1213.

Here's Why Marijuana Impairs Memory Formation

Scientists have known for some time that marijuana impairs the ability to convert short-term or working memories into lasting form. Now they know why. The protein synthesis machinery in the hippocampus is necessary to accomplish lasting memory formation, and a study of mouse hippocampus revealed that marijuana impairs the protein synthesis pathway responsible for memory consolidation.

Source:
Puighermannal, E. et al. 2009. Cannabinoid modulation of hippocampal long-term memory is mediated by mTOR signaling. Nature Neuroscience. On-line edition, Aug. 2; doi:10.1038/nn.2369

Increasing Working Memory Makes Even Adults Smarter

I have pointed out a study in an earlier post a study that showed the IQ of children around age six can be increased by training them to increase their working memory capacity. This ability of working memory training to improve intelligence has now been demonstrated in young adults (mean age = 25.6 years). Subjects were trained on a so-called dual n-back test in which subjects were asked to recall a visual stimulus that they saw two, three or more stimulus presentations in the past. The task was dual in the sense that two stimuli were presented simultaneously for a half second, followed by a 2.5 second delay until the next stimulus. One stimulus type was a square in which another smaller square was shown in one of eight possible positions within the larger square. At the same time one of eight consonants were presented through headphones. A response was required every time one of the presented stimuli matched the one that had been presented n positions back in the sequence. As performance improved with each block of trials, the task demands were increased my shifting from two-back to three, then three to four, etc. Daily training took about 25 minutes.

Intelligence tests were periodically given that were based on visual analogy problems of increasing difficulty. Each problem presented a matrix of patterns in which one pattern was missing. The task was to select the missing pattern among a set of given response alternatives. This kind of testing measures what is called "fluid" intelligence, which refers to the ability to reason and solve new problems independently of previously acquired knowledge. What the investigators found was that working memory training improved scores on the intelligence test. Moreover, the effect was dose-dependent, in that intelligence scores increased in a steady straight-line fashion as the number of training sessions increased from 8 to 12 to 17 to 19. Working memory capacity presumably transfers to visual analogy tasks because you have to hold many visual features in working memory while you try to identify which pattern is missing in the matrix.

These results also challenge a widely held view that intelligence becomes fixed at a young age and cannot be increased by experience.

Source: Jaeggi, S. M. et al. 2008. Improving fluid intelligence with training on working memory. Proc. Natl. Acad. Science. www.pnas.org/cgi/doi/10.1073/pnas.0801268105

Txting Is Dangerous 4 U

"Dr. Laura" has written a very interesting blog item about text messaging on cell phones. She reminds us all of just how distracting texting is.

And when it comes to memorizing, texting is devastating for learning, unless of course you are texting about the content you are learning.

50 Tips to Improve Memory

One of the followers of this blog sent me a link to her blog that recently posted an article, "50 Ways to Make Your Memory More Like an Elephants" (http://www.onlineuniversities.com/blog/2009/06/50-ways-to-make-your-memory-more-like-an-elephants/).

The tips are not documented, but they do seem consistent with what I know about the research literature. Ten tips deal with diet, and these generally advocate foods that are high in omega 3s and antioxidants. Few of these have ever been shown to have memory-specific effects, but they all promote general health.

Another large batch of tips deal generally with lifestyle, but some ideas are not very profound, such as "don't get too drunk."

Five tips suggest ways to be more organized, such as using Evernote and using Google Calendar, both of which I find to be useful.

The list closes with some brain exercises. These are not memory specific, but they are good for the brain and thus good for memory.