Re: New studies shed light on why quality sleep is so important to learning things, and why we forget things (it's often due to interference)

[Guest guest]

very interesting, thanks Live.

>

> http://www.eurekalert.org/pub_releases/2006-12/m-lds120506.php

>

>

> Public release date: 5-Dec-2006

>

> Contact: Hahn

> thahn@...

> 49-622-148-6463

> Max-Planck-Gesellschaft

>

>

> Learning during sleep?

>

> If I can't remember this morning where I put my car keys last night,

> it's due to my memory failing me again. Scientists at the Max Planck

> Institute for Medical Research in Heidelberg have been investigating

> how memories might be consolidated. Their new study offers the

> hitherto strongest proof that new information is transferred between

> the hippocampus, the short term memory area, and the cerebral cortex

> during sleep. According to their findings and contrary to previous

> assumptions, the cerebral cortex actively controls this transfer.

The

> researchers developed a new technique for their investigations which

> promises previously impossible insight into the largely

> under-researched field of information processing in the brain

(Nature

> Neuroscience, November 2006).

>

> The question of how the brain stores or discards memories still

> remains largely unexplained. Many brain researchers regard the

> consolidation theory as the best approach so far. This states that

> fresh impressions are first stored as short-term memories in the

> hippocampus. They are then said to move within hours or a few days -

> usually during deep sleep - into the cerebral cortex where they

enter

> long-term memory. Investigations by Hahn, Mayank Mehta and

the

> Nobel Prize winner Bert Sakmann from the Max Planck Institute for

> Medical Research in Heidelberg have now shed new light on the

> mechanisms that create memory. According to their findings, the

areas

> of the brain work together, but possibly in a different way from

that

> previously assumed. " This is a technically sophisticated study which

> could have considerable influence on our understanding of how nerve

> cells interact during sleep consolidation, " confirmed Edvard Moser,

> Director of the Centre for the Biology of Memory in Trondheim,

Norway.

>

> It has been difficult up to now to use experiments to examine the

> brain processes that create memory. The scientists in Heidelberg

> developed an innovative experimental approach especially for this

> purpose. They succeeded in measuring the membrane potential of

> individual interneurones (neurones that suppress the activity of the

> hippocampus) in anaethetised mice. At the same time, they recorded

the

> field potential of thousands of nerve cells in the cerebral cortex.

> This allowed them to link the behaviour of the individual nerve

cells

> with that of the cerebral cortex. The researchers discovered that

the

> interneurones they examined are active at almost the same time as

the

> field potential of the cerebral cortex. There was just a slight

delay,

> like an echo.

>

> This was a surprising finding, because the interneurones suppress

> those neurones in the hippocampus which are supposed to write

> information to the cerebral cortex precisely during phases of high

> activity. According to Mayank Mehta the result can be interpreted in

> very different ways. " Either the mechanism contributes to memory

> consolidation, or the information transfer from one part of the

brain

> to another during sleep does not proceed as we have previously

> assumed. " The brain researchers now want to find out which of the

> possible explanations applies.

>

> In any case, the scientists can use their new experimental method to

> investigate many other open questions in brain research. Hahn

> emphasised: " Putting the behaviour of a single neuron in the context

> of wider-scale patterns of activity promises to yield completely new

> insights into the principles according to which our brain is

> organised. "

> ###

>

> Original work:

>

> Hahn, Bert Sakmann & Mayank R. Mehta Phase-locking of

> hippocampal interneurons' membrane potential to neocortical up-down

> states Nature Neuroscience, November (2006)

>

>

> -------

>

>

> http://www.eurekalert.org/pub_releases/2006-12/uow-ccr120406.php

>

> Public release date: 4-Dec-2006

>

>

> Contact: Brad Postle

> postle@...

> 608-262-4330

> University of Wisconsin-Madison

>

>

>

> Controlling confusion -- Researchers make insight into memory,

forgetting

>

> MADISON -- Why do we forget? Do memories decay on their own, or are

> they harmed by interference from similar memories? Using a technique

> called " transcranial magnetic stimulation " (TMS), brain researchers

at

> the University of Wisconsin-Madison may have found the answer.

>

> Although the notion of decay makes sense, Brad Postle, assistant

> professor of psychology at UW-Madison, says it may be inaccurate.

>

> " Psychologists have known for decades that the intuitive notion of

> decay is probably less of a factor in forgetting than is

> interference, " he says. Interference occurs, he says, when " other

> remembered information disrupts, competes with or confuses the

> information that you want to remember. "

>

> Interference is always present, Postle says, but we don't always

notice it.

>

> " An obvious case is like yesterday, when a friend was telling me his

> cell phone number but actually gave me his home phone number, " he

> says. Another scenario is equally familiar: we get most details of

the

> story right, but misidentify the source. Or we remember that the

> quotation comes from Shakespeare, but we name the wrong play.

>

> " Interference is also often to blame, " says Postle, " in cases when

we

> simply can't remember something. "

>

> If blocking interference is so important to a good memory, where -

and

> how - does that blocking occur " In a study published in the

> Proceedings of the National Academy of Sciences on the week of Dec.

4,

> 2006, Postle - together with Guilio Tononi of the UW-Madison School

of

> Medicine and Public Health, and Eva Federoes, a researcher in the

> UW-Madison department of psychology - studied how part of the

brain's

> prefrontal cortex can reduce the disruptive effects of interference.

> The prefrontal cortex is responsible for complex thought.

>

> From brain scans, scientists already knew that the sub-region under

> study, called the inferior frontal gyrus, or IFG, is active when

> volunteers take memory tests while confronting interference. But was

> the IFG essential to controlling interference, or was it just

> contributing more brain horsepower to complex memory tasks " To

answer

> that question, the researchers temporarily disrupted the IFG using

> TMS, a noninvasive technique that shows potential for treating

> depression and other disorders.

>

> " TMS is a technique that allows the induction of a current in the

> brain using a magnetic field that passes through the scalp and the

> skull safely and painlessly, " says Tononi, a pioneer in refining the

> technique for brain research. " TMS can be used to briefly 'scramble'

> neural activity in the underlying brain area for a short time,

> typically a second or so. This scrambling is fully reversible, and

> after the pulsing, the targeted brain area becomes fully functional

> again. "

>

> Neuroscientists have traditionally identified the roles of

particular

> parts of the brain by studying people with brain injury. TMS allows

> them to do a similar study on healthy volunteers, Tononi says.

>

> " The great advantage for researchers, " he says, " is that one can

test

> whether a given brain area is causally involved in producing a given

> behavior, but as soon as the current is turned off, the brain

returns

> to normal. "

>

> In the current study, volunteers read a group of letters ( " F, B, P,

> X " ), and were asked a few seconds later whether a particular letter

> had appeared in the most recent group ( " Did you just see a 'Z' " " ).

In

> this type of test, having seen a " Z " in the string-before-last

causes

> interference that makes the task more difficult. The subjects take

> longer to respond, and are more likely to incorrectly say " yes. "

>

> The research set-up was designed to be a simplified version of many

> everyday memory challenges, says Postle. Without a good sorting

> mechanism, our brains would be utterly confused by the vast amount

of

> observations, ideas and memories that we have stored away. We might,

> for example, dial the phone number of the friend we just called

rather

> than the one we intended to call.

>

> In previous studies of interference, the IFG consistently lit up in

> brain scans, showing that it does something when the memory tries to

> deal with interference. But the IFG could simply be contributing

some

> type of generic processing power to the task, says Postle.

>

> However, the new study proved that the IFG is essential to blocking

> interference, he says, because accuracy plummeted when the IFG got a

> brief jolt of magnetic stimulation at the exact moment when the

> subject was confronting confusion.

>

> Eventually, Postle hopes that locating the site of specific memory

> operations in the brain may help the millions of people with

declining

> memories. " Understanding how the brain controls interference may be

a

> first step to helping people with memory problems, " he says.

>

> The precise system used to target the magnetic pulse has many other

> applications in neuroscience research and treatment, Tononi

adds. " TMS

> can be used not only to disrupt brain activity, but also to change

it.

> If applied repeatedly, TMS can strengthen certain circuits that have

> become pathologically weak, " he says.

>

> TMS is already being tested to treat severe depression, one of the

> most serious psychiatric illnesses. In studying this treatment, he

> adds, " It is important to be able to target TMS exactly to the right

> area for each individual brain, just as we did in this study. "

> ###

>

> EMBARGOED FOR RELEASE AFTER 5 P.M. EST MONDAY, DEC. 4, 2006

>

> Tenenbaum, (608) 265-8549, djtenenb@...

>