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Author Topic: Improve memory with sleep, practise and testing- (Aug, 2010 bioscience headlines  (Read 3111 times)
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Francis Umeoguaju
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« on: August 23, 2010, 09:00:18 am »


Improve memory with sleep, practise and testing- (Aug, 2010 bioscience headlines)


There are whole mar­kets (think cross­words, herbal sup­ple­ments, drugs, brain fit­ness soft­ware) aimed at help­ing us improve our memory. Now, what is “mem­ory”? how does the process of mem­ory work?

Dr. Bill Klemm, Pro­fes­sor of Neu­ro­science at Texas A&M Uni­ver­sity, explains a very impor­tant con­cept below.

Mak­ing Mem­ory Con­sol­i­da­tion Work
By Bill Klemm,  Ph. D.
Until con­sol­i­da­tion has occurred, a short-term mem­ory is very vul­ner­a­ble, as all of us have expe­ri­enced from look­ing up a phone num­ber only to have some dis­trac­tion cause us to lose the num­ber before we can get it dialed.
What is “consolidation”?
Brain researchers use the term “con­sol­i­da­tion” for the process whereby short-term mem­ory gets made more permanent.
Here, I would like to dis­cuss some aspects of con­sol­i­da­tion that many peo­ple may not know about: why sleep is so impor­tant, why mem­ory must be prac­ticed, and how test­ing pro­motes consolidation.

1. Over-training: You Can Learn Too Much
Exper­i­ments have shown that human mem­ory per­for­mance unex­pect­edly dete­ri­o­rated if learn­ing ses­sions were increased to four 60-minute ses­sions at reg­u­lar inter­vals on the same day. In other words, the more the sub­jects were trained, the poorer they per­formed. How­ever, this inter­fer­ence did not occur if sub­jects were allowed to nap for 30–60 min­utes between the sec­ond and third sessions.
It is hard to explain why over-training dis­rupts per­for­mance, but I sus­pect that as train­ing tri­als are repeated the infor­ma­tion starts to inter­fere with mem­ory con­sol­i­da­tion, per­haps because of bore­dom or fatigue in the neural cir­cuits that medi­ate the learn­ing. Nap­ping must have a restora­tive func­tion that com­pen­sates for the neg­a­tive effects of over-training. What all this sug­gests is that mem­ory con­sol­i­da­tion would be opti­mized if learn­ing occurred in short ses­sions that are repeated but only with inter­ven­ing naps and on dif­fer­ent days with reg­u­lar night-time sleep. In other words, repeat­ing long study peri­ods in the same day on the same task can be counter-productive. This is yet another rea­son why stu­dents should not cram-study for exams. Learn­ing should be opti­mized by rehears­ing the same learn­ing mate­r­ial on sep­a­rate days where nor­mal sleep occurred each night.
Sources:
   - Maquet, P. et al. 2002. Be caught nap­ping: you’re doing more than rest­ing your eyes.Nature Neu­ro­science. 5 (7); 618–619.
   - Med­nick, Sara, et al. 2002. The restora­tive effect of naps on per­cep­tual deterioration.Nature Neu­ro­science. 5 (7): 677–681.
   
2. Los­ing Your Past
Do you remem­ber the names of your elementary-school teach­ers? How about the name of the bully in mid­dle school? Or names of your friends when you were a kid? These are all things you remem­bered well at one time and remem­bered for a long time. But you may well have for­got­ten by now.
A recent study on rats sug­gests what it takes to sus­tain longer term mem­o­ries. Rats in the study learned a “bait shy­ness” task. Rats were given a drink of saccharin-flavored water, and then shortly after­wards injected with lithium, which made them nau­se­ated. This was a typ­i­cal con­di­tioned learn­ing sit­u­a­tion, as with Pavlov’s dogs. In this case, rats typ­i­cally remem­bered to avoid such water for many weeks. This is the basis for “bait shy­ness.” If rats sur­vive a poi­son­ing episode, they will avoid that bait in the future. In this exper­i­ment, one group of rats received an injec­tion directly into the part of the brain that holds taste mem­o­ries. This injec­tion con­tained a drug that blocks a cer­tain enzyme, a pro­tein kinase. These rats lost their learned taste aver­sion. The bad mem­ory was lost irre­spec­tive of when the injec­tion was made dur­ing the 25 days after learn­ing occurred. Giv­ing the enzyme blocker before learn­ing had no effect on learn­ing to avoid the fla­vored water. The pro­tein kinase thus seems to be nec­es­sary for sus­tain­ing a long-term mem­ory. It is pos­si­ble that other long-term mem­o­ries the rats may have had were also wiped out by the enzyme-blocking drug.
So what is the prac­ti­cal impor­tance? I sug­gest that even “long-term” mem­o­ries have to get rehearsed or they may even­tu­ally for­got­ten. Or if you do remem­ber, there is a good chance that the mem­ory is cor­rupted, that is, not totally cor­rect. The con­se­quence is that things that hap­pened long ago may be either for­got­ten, or misremembered.
What sus­tains the enzyme nec­es­sary for long-term mem­ory? I sus­pect it is rehearsal and peri­odic reac­ti­va­tion of the mem­ory. Some sci­en­tists are excited about the pos­si­bil­ity of devel­op­ing a drug to manip­u­late lev­els of the enzyme. The prob­lem with that, how­ever, is that the drug could abol­ish old mem­o­ries that you might not want to for­get (like your name) or may cause you to remem­ber too much that is now irrelevant.

Accessed from <http://www.sharpbrains.com/blog/2008/07/09/improve-memory-with-sleep-practice-and-testing/>

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