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East Asia Child Science Exchange Program 4: Brain Science and Second Language Acquisition

<Human languages and changes in gene sequences>

There are various views on the generation and acquisition of languages in terms of linguistics, and we definitely need more research on this topic to determine which theory is the right one. At the present stage, therefore, we should carefully identify the facts that have been already discovered and those that await discovery. Today, I would like to briefly explain some of the interesting discoveries in language acquisition in recent years, starting from the perspective of evolution.

The most important feature of human beings is the ability to communicate through language. Their acquisition of hierarchical grammars in the course of evolution contributes significantly to distinguishing humans from all other animals. It still remains a mystery how humans acquired such ability and at which stage of evolution; various research studies are currently being conducted to find out the answer.

Chimpanzees are said to be the closest animal relative to humans. Gene analysis shows, for example, that the difference in DNA sequence between humans and chimpanzees is only about one percent; according to some scientists, however, this slight difference may have caused human beings to acquire languages.

In a related study, researchers in the UK announced in 2001 the results of genetic studies on children of a certain family whose members suffered from the inability of understanding part of grammatical rules. To be more precise, they discovered (this is yet considered as a working hypothesis) the locations of two mutations in FOXP2, which is one of transcriptional regulators, in this family.

The human FOXP2 in fact differs in its specific gene sequences from other versions of animals. Based on this fact, one hypothesis has been proposed that human beings became capable of speaking language as a result of small variations in the sequence of the three billion DNA base pairs.

This FOXP2 is also considered to be a fundamental gene associated with autistic and other disorders. Some scientists have suggested its potential role in the development of various brain functions such as the formation of nerve connections and synapse construction.

<Relative pitch and language origins>

Recently I have started thinking about the importance of relative pitch in elucidating the origin of language. We often hear that having absolute pitch is critical to becoming a good musician, but this belief is likely to lead to misunderstanding since it is the development of relative pitch in the process of human evolution which has a great deal to do with the essence of what it is to be human. In fact, absolute pitch is rather primitive in biological terms as it can be found in insects, etc.

Here a simple example illustrates why relative pitch is so important. When a father and mother say "Good morning," to their child, their pitches are obviously completely different; nevertheless, the child pays no attention to the difference and accepts them as the same phrase. This is because we have relative pitch, which enables us to recognize sounds, in the same category, even though the sounds have different pitches. I think this relative sense of speech may have some relationship to the origin of language. Chimpanzees, in contrast, rarely have relative pitch.

<Primary sensory area and a critical period for language development>

Whenever we talk about foreign language learning, the word "critical period" comes up. There are well-known studies on imprinting in newborn animals by Dr. Konrad Lorenz and Dr. Eckhard Hess, and the experimental results released in 1959 clearly substantiate that imprinting does not occur after the first 24 hours of birth, i.e., a critical period.

This is why we often hear, and sometimes misunderstand, that humans have such a critical period as well. In fact, this concept can be applied but only to a limited extent, mostly to the sensory areas such as the visual and auditory senses. For example, according to an experiment by Dr. Patricia Kur, a baby begins to hear and recognize consonant sounds before vowels; however, by the age of 12 months, this ability will diminish and the baby cannot recognize consonant sounds afterwards. It is said that after adulthood, Japanese speakers cannot hear accurately the difference between "L" and "R" sounds as the Western people do, no matter how hard we try. Therefore, an obvious critical period exists for the primary sensory areas, but rarely for the higher state of cognitive capacity.

In recent years, some progress has been made in elucidating the mechanism of how this critical period is formulated. Researchers such as Dr. Takao K. Hensch at the Japan Science and Technology Agency's Core Research of Evolutional Science & Technology (JST-CREST) report a close relationship between the critical period and GABA, the major inhibitory neurotransmitter of the brain. In their theory, the critical period can be controlled by a benzodiazepine, which enhances GABA function, hence the timing of the critical period can be accelerated; that is, the learning period can be brought forward. On the other hand, if we wish to continue learning with the brain of a young child, we should do just the opposite. In their experiments, DMCM was used as an antagonist of GABA function to lengthen the critical period; therefore, even an older brain should be able to work as a young brain. Of course, this is the case within animal experimentation.

<Age and foreign language learning>

There have been several studies on the effects of age on the rate of learning a second language. One experiment measured the progress of native Spanish speakers of different ages who were learning English as a second language. The total sample was 61 people; those who had immigrated in their early years showed significantly higher levels of ability to acquire the second language.

Meanwhile, there are some cases of people who had passed the critical period, but successfully attained a native level of proficiency in the second language.

Another research study observed a mature Danish person who started to learn English later in life and became as fluent as a native speaker. Although we should take into account in this case the close relationship of these two languages in terms of linguistics, it is, nevertheless, quite surprising to see how much potential there is for language acquisition at this stage of life.

On the other hand, there have been cases of people who could not master English even though they had started learning when they were young and had been properly taught.

For example, children from English-speaking families studying at a French language school later showed different levels of achievement in learning French: some children could speak very fluently, while others were unable to attain any second language competency.

<The importance of motivation in learning>

In thinking about learning, we should take into account the important role of motivation. When we are intent on doing something, a chemical called dopamine is produced in the brain, and this, according to recent research data, is said to have significant influence on memory formation. Thus, to put it simply, a passionate eagerness is the key. Once we have enthusiasm or great interest that pushes us toward performing a certain action, all the debate about critical-period matters will be forgotten.

Structurally, the evolution of the human brain has been taking place in the center of the brain and spreading outwards. The brainstem, necessary for sustaining life, is located in the central part. Similar in shape to that of reptiles, it can be traced back to an early stage of brain evolution. The limbic system, called the "old mammalian brain," controls vital functions, and without this, we would be unable to utilize knowledge and experience.

The cerebral neocortex including the prefrontal region is a product of the last stage of brain evolution, and exhibits the most essential features of the human brain, enabling us to live as civilized human beings. Nonetheless, no matter how much this part is nurtured by education, our intelligence is likely to be wasted if we fail to have a strong interest or motivation from the inside to do or achieve something. In particular, early education and child-rearing that involve the development of vitality within the brain during infancy are considered essential.

<Interaction between brain functions and the development of infants>

The primitive stage of brain development during infancy is very important, however there have not been enough studies carried out to solve this mystery. Behavioral studies have yielded valuable data in recent years; however, it is still poorly understood how the baby's brain develops and what happens there while the baby is in the womb or after birth, as well as how nerve connections occur inside the brain.

We tend to think that the functions of each part of the brain exist as individual elements, but in fact, they work in concert with each other. Each of the brain functions such as awakening, sleeping, emotion, physical movement, thinking, speech, etc. are linked to each other. A typical case is autistic spectrum disorder, especially in Kanner-type autism, in which symptoms of speech, motion, and sleep disorders are the results of the mutual interaction of brain functions.

Therefore, it will be a key challenge for the future of neuroscience to figure out how these functions are linked to one another and develop within the brain in the earliest years of life.

While conducting joint research with other specialists on this topic of the comprehensive linkage of brain functions, I have become obsessed with my own conviction that art can benefit not only brain function but also to brain development.

Like art, language is also closely linked to the interaction of the brain functions. When we think of language, we must start by asking why we have language, for what purpose languages are to be used, and how we should start teaching children languages, from an interdisciplinary perspective.

Brain activity of a newborn baby upon hearing the mother tongue

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