NRSC 2110 Blog

Our society has become a sleep deprived one which has lead researchers to study the effects of it. It has now been accepted that sleep is needed for memory consolidation. Does sleep improve all types of memory? People generally think so but what if a study found that to not be true?

Researchers at Georgetown University and Catholic University have apparently found an exception to this idea of memory consolidation during sleep for motor sequence learning. I found this article to catch my eyes easily as having taken a class on the neurobiology of learning and memory; the researchers were definitely daring to challenge this already accepted idea. They focused their study on implicit consolidation which I found interesting because it seems that dreaming of performing a patterned motor sequence and remembering would help the most.

In their study,(http://www.jneurosci.org/content/27/46/12475.full.pdf+html) the researchers studied 36 right-handed college students at 3 different visits with half of the participants tested in the morning (8am) and half in the evening (8 pm). The morning group had 12 hours of awake-rest between their 1st and 2nd visits and 12 hours of sleep between their 2nd and 3rd visits. The evening group had the opposite, with the sleep full rest first. Also half of the participants were given instructions with mention of the patterned sequences and half were just given minor instructions. In addition, 18 right handed subjects were used as controls and were allowed to sleep in between the 3 testing?s.

For each visit the subjects were given the alternating serial response time task which involved the subjects responding to pushing a button to a target (a filled in circle) that appeared in one of 4 circles that were aligned in a row. The circle stayed filled in until the correct key was pressed. Then another circle filled in and the experiment with 8 warm-up trials and then 80 experimental ones consisting of patterns which alternated with random trials. The researchers also performed cued and probed time trials to differentiate between pattern and random trials. (Note: my explanation of their study might be a bit confusing but that?s because I found theirs not as well explained as it could have been. Unless, of course I went to another study which they directed me to a study with a better description of the methods)

The researchers found that daytime enhancement occurred for overall reaction time but not for pattern specific learning. Speed only improved if the rest period was over the day and not when it was overnight. This seemed very odd to me (which they kind of admitted to) and makes me believe it was poorly constructed. It seems obvious that college kids are going get better after 8 am as most college kids are still asleep at 8. Maybe if they did it at 10 am and 10 pm or if they had to be awake for, say, 2 hours before the test. The results might have been different then.

In the end, I found the title very interesting and it made me want to read the article but I was disappointed. The article wasn?t written as clearly as it should have been and I had a hard time following it. It referred to other papers so many times that I found it distracting. With that fact and the fact that the experiment was poorly conceived, it seemed to me that their experiment didn?t test anything new and that they were just testing what others already have. They also had so many different discussions that that also made the paper rather confusing.

I would have liked to have seen something more than just behavioral testing. For example, it would have been more interesting if they measured the subject?s brain activity during the tasks. More neuroscience testing would have helped make their research stronger. Also, while reading the article, I found myself wondering why studying sleep-dependent consolidation of implicit patterned motor learning is even important. How would that be beneficial to us? I can definitely see the use in researching sleep-dependent consolidation for motor learning in general but why would learning about sleep-dependent consolidation and patterned motor learning exactly help us with our lives? I?m all ears if someone could give me an example to change my mind. Again, I definitely believe research should continue on consolidation and motor learning and I find that fascinating.

The last thing I?m going to note involves their last sentence which they mentioned interpreting implicit consolidation features saying, ?deciphering each component will make it possible to better understand and use off-line (implicit) performance enhancements?. The performance enhancements part slightly bothered me because that brings up a whole can of ethical issues but I?ll save that for another time.