Distinctions between adults and children brain

Those who talk about physiological changes in the brain after age X, can you please point to relevant scientific articles? Right now I tend to believe what Mxsmanic wrote, that the difference between children and adults is purely motivational.

Using MRI and animation technology to study the brains of children, researchers like Dr. Paul Thompson of UCLA have discovered that children are processing language information in a different region of the brain than adults.
http://www.acfnewsource.org/science/learning_language.html


1. Learning changes the physical structure of the brain.
2. These structural changes alter the functional organization of the brain; in other words, learning organizes and reorganizes the brain.
3. Different parts of the brain may be ready to learn at different times.
...
Very young children discriminate many more phonemic boundaries than adults, but they lose their discriminatory powers when certain boundaries are not supported by experience with spoken language (Kuhl, 1993). Native Japanese speakers, for example, typically do not discriminate the "r" from the "l" sounds that are evident to English speakers, and this ability is lost in early childhood because it is not in the speech that they hear.
...
Synaptic connections are added to the brain in two basic ways. The first way is that synapses are overproduced, then selectively lost. Synapse overproduction and loss is a fundamental mechanism that the brain uses to incorporate information from experience. It tends to occur during the early periods of development.
...
http://www.nap.edu/html/howpeople1/ch5.html

A few more snippets from: http://www.nap.edu/html/howpeople1/ch5.html

Neuroscientists study the anatomy, physiology, chemistry, and molecular biology of the nervous system, with particular interest in how brain activity relates to behavior and learning.
...
Some neuroscientists explain synapse formation by analogy to the art of sculpture. Classical artists working in marble created a sculpture by chiseling away unnecessary bits of stone until they achieved their final form.
...
In summary, neuroscience is beginning to provide some insights, if not final answers, to questions of great interest to educators. There is growing evidence that both the developing and the mature brain are structurally altered when learning occurs.

None of this is evidence of a physiological change from childhood to adulthood. A shift in brain activity does not necessarily indicate a shift in brain function, just as a shift from Microsoft Word on a PC to Flight Simulator does not necessarily indicate that any hardware changes have occurred on the motherboard.

There is _no_ proof of any physiological change that fundamentally alters language learning between childhood and adulthood. Non-physiological explanations are available for every observation made thus far, and they are just as plausible as the physiological explanations. The notion that children are physiologically different from adults with respect to language learning is accepted linguistic dogma, not proven fact. The dogma is most readily accepted by linguists who can't learn other languages, and is considered the most questionable by people who _have_ learned languages with native proficiency in adulthood (thus incontrovertibly disproving the idea that some physiological change prevents this).

For the sake of the argument let's pretend there is no physiological change from childhood to adulthood. It doesn't really matter if we look instead at a shift in brain activity (ie. entire brain to left hemisphere). If left hemisphere thinking is a trait of adults but not of children for language, then it's obvious there are differences in cognitive task specialisation and abilities.

As for the computing analogy, the hardware isn't so important as the firmware or the software. A Flight Simulator can perform word processing functions, but not as well as a Word Processor, eg. the virtual pilot can take notes during the mission briefing and the fonts have to be emulated with the graphics engine with the game. The Flight Simulator will be run a lot more often than the Word Processor on a system designated to gaming; the system's resources would be tailored to favour game use. So the system won't perform word processing duties so efficiently.

Linguistic dogma isn't important nor is whether linguists can learn languages or not; linguists don't use MRI technology or study brain physiology. What say do they have with regard to brain physiology?

There could be some people who have learned languages with native proficiency in adulthood, but it's virtually zero (compared to those who start from childhood). Normally, only people from childhood and on, learn languages with native proficiency. This doesn't mean it's impossible for adults: I even doubt that the majority of linguists suggest this.

PS: if there are "linguists who can't learn other languages" then you are contradicting yourself.

Tom,

It is wrong to say that changes happens _after_ a certain age, because it happens all the time. At early age, brains develop rapidly and important for a child to receive enough input to form and develop the language center in his brain. I think that the critical age is about 7, and if a child was not taught any language before, then he will have seriously problem with acquiring even his/her first language.

The Critical Period Hypothesis
http://www.feralchildren.com/en/critical.php

I also I have read a study that suggests lateralization of language processing increase rapidly up to age 5, then continue more slowly up to 25, after that age it gradually decreases.

There were a few studies on early and late bilinguals. One study has shown that early bilinguals use the same region of their brain for both languages, while late bilinguals use differently. But the result of another study has suggested that it is more correctly to attribute that to proficiency than age. The following article gives a quick review of previous studies and then provides reasonable explanation of its own study:

The Effects of Age of Acquisition and Similarity of L1 and L2 on the Bilingual Brain: an fMRI Study
http://www.owlnet.rice.edu/~dburgund/480-580_04/Bilingual_Brain.pdf

Also, I would suggest to take a look on the following presentation, which quickly summarize of many results known today.

Language and the Developing Brain
http://www.childreninc.org/pdf%20files/Eliot-Language.pdf

As you well know, the critical period hypothesis pertains to the acquisition of a first language. It says that you have to learn your first language before a certain age; otherwise, you will never be fully proficient in language.

The hypothesis says nothing about second language acquisition. It does not say that you have to learn your second language before a certain age.

This presentation:
http://www.childreninc.org/pdf%20files/Eliot-Language.pdf
describes an interesting experiment (Thanks Dwayne for the link!), which most people would say proves the critical period hypothesis for second language acquisition.

But isn't it equally possible that children who immigrate to the US after age 7 are simply less motivated to learn the language well? The older you are, the less likely your peers are to make fun of you because of your foreign accent or poor grammar, so you have fewer reasons to take English seriously.

===
Korean and Chinese immigrants were asked to identify ungrammatical phrases. Those who had arrived in the U.S. before 7 years of age performed as well as native-born speakers. Grammatical skill then declined as a function of age of immigration, reaching a plateau after 17 years.

Evoked potential measurements of second language processing differ between subjects who learned the language at different times in life. Compared to early-learners, late-learners show deviant activity (in the frontal lobe) during a grammatical task. However, brain activity (in the parietal-temporal area) during a word identification task did not differ between early- and late-learners. (Recall that Broca’s area is more important for grammatical processing, and Wernicke’s,
for word meaning.)

All of the subjects in this study were tested as adults, and had lived here for at least 30 years, so their level of competence in English had plateaued. In this test, subjects do not need to understand or be able to state grammatical rules, only to decide whether or not a recorded sentence sounds correct. Examples of the kind of sentences used to test grammatical fluency:
“The farmer buys two pig at the market.” (missing plural -s)
“The little boy is speak to a policeman.” (missing -ing verb ending)
“Yesterday the hunter shoots a deer.” (wrong verb tense)
“Tom is reading book in the bathtub.” (missing definite article)
“The man climbed the ladder up carefully.” (misplaced preposition)

In one sense, this test is rather difficult: many of these mistakes would sound correct if translated literally into the subjects’ native language. On the other hand, the test is easy enough that native speakers as young as six years old can score perfectly.

The data show that the critical period for language-learning begins to close around age seven and ends by the end of puberty. After age 17, it didn’t matter when the subjects began to learn English, their grammatical usage was comparably poor.

How else would you explain the following, if not in terms of physiology?

"Very young children discriminate many more phonemic boundaries than adults, but they lose their discriminatory powers when certain boundaries are not supported by experience with spoken language (Kuhl, 1993). Native Japanese speakers, for example, typically do not discriminate the "r" from the "l" sounds that are evident to English speakers, and this ability is lost in early childhood because it is not in the speech that they hear."

and

"1. Learning changes the physical structure of the brain.
2. These structural changes alter the functional organization of the brain; in other words, learning organizes and reorganizes the brain.
3. Different parts of the brain may be ready to learn at different times."

As I understand the above, experience with spoken language alters physiology and very young child don't have this experience to the same extent that adults do.

child->children

There's no proof that learning changes the physical structure of the brain.

These questions are important because physical changes would create an absolute obstacle to acquisition of native proficiency in a second language. Other changes would not. It's rather like saying that girls can never be CEOs because the physical structure of their brains prevents it.

The existence of people who do acquire native proficiency in new languages well after puberty proves that no physical change is preventing such acquisition.

The proof is derived by imaging techniques used by scientists who study brain physiology. That's why these findings are being published and taught, as you can see. If none of it were true, then this would suggest a conspiracy theory: impossible to uphold. There's no conspiracy.

Physical changes wouldn't necessarily create an absolute obstacle to acquisition of native proficiency in a second language. There's nothing to suggest this and it doesn't mean adults can't acquire native proficiency in new languages. All it tells us is that language acquisition is different in adults compared children. Differences in physiology don't equate to prevention of language acquisition by adults.

>>There's no proof that learning changes the physical structure of the brain.<<

Here is an example of proof obtained by MRI scans that learning changes the physical structure of the brain and that a certain activity is correlated to a specific region of the brain. There's plenty of demonstrated proof of this sort littered all over the web to temper your anti-establishment sentiment.

http://www.biol.tsukuba.ac.jp/~macer/EJ141/ej141j.htm

"Magnetic Resonance Imaging (MRI) studies have confirmed that, for example, the brain region which controls finger movement in the hand increases in size in string players engaged in specific 'fingering' exercises."

>>"Magnetic Resonance Imaging (MRI) studies have confirmed that, for example, the brain region which controls finger movement in the hand increases in size in string players engaged in specific 'fingering' exercises." <<

The reason for this is, as I see, that the more you are involved in an activity, the more neural connections are formed for that particular function. This can also explain the ease with which people who have learnt a foreign language will learn a new one even more easily. But I guess this does not depend on age, or at least not completely.

>>that particular function<<

BRAIN function, that is...