Language development in the brain

A new breakthrough has been made concerning language development in children. Researchers at King’s College London and Brown University took brain scans of over 100 children to identify the levels of myelin in their brain.

Myelin is an insulating material that forms a sheath around the axon of neurons. The material increases the speed of impulses in the brain and the spinal cord. The increase of myelin is part of the maturation and development of language. In theory, the more sheath, the messages are sent more rapidly and therefore children have more language abilities.

A link between language and the frontal left cortex has been established for many years. As part of my EPQ, I conducted a dichotic listening experiment to investigate this further and concluded that over 80% of my subject has specialisations in their left hemisphere. Due to this link, scientists expected to find more myelin in the frontal left hemisphere. As hypothesised, they did discover that the levels of myelin were asymmetric as the left hemisphere has a denser amount of myelin. However, the study shows that the levels of myelin increased at the same rate in both hemispheres from the age of 1 – showing that the increased amount of myelin was already there. This shows that the amount of myelin may not account for the increased language ability in children, but shows the importance of the child’s environment.

The scientists also found that the myelin had a stronger influence on language until they were 4 years old and that after the 4 year old marker, the levels of myelin remained mostly constant. This explains how children learn their first language so quickly and how children are more able to become fluent in a second language than an adult. This suggests that there is a ‘critical period’ (Chomsky) for language. This also sheds a new light on Piaget’s theory of the different developmental stages that children go through. The first two are:

·         Up to 2 years old - sensory motor stage

·         2-7 years old - preoperational from stage

Piaget specified that the first stage depends greatly on social environment and exposure to language so the brain begins to become asymmetrical. If a child is in the right environment, the frontal lobes increase in size greatly. During the next stage, both Wernicke’s and Broca’s area are said to develop most, however the brain growth slows down after half way through this stage.

These hypotheses are reinforced to a certain extent by this new research, showing that the environment that children grow up in are very important, that the brain develops (as the levels of myelin increase) and that the critical period for language is about four years old.

As quoted from Dr Sean Deoni from Brown University:

"This work is important as it is the first to investigate the relationship between brain structure and language across early childhood and demonstrate how this relationship changes with age." 

To read more visit: http://news.brown.edu/pressreleases/2013/10/language

http://www.bbc.co.uk/news/health-24446292

 

Language and the brain

Until recently, the brain has been a mystery. Now, after scientific advancements, some areas of the brain have been linked to language.

Primary Somatic Motor Area

Penifield and Roberts (1959) located the primary somatic motor area and discovered that it controls all voluntary bodily movements. This area stretches down from the top of the braina dn runs through both hemispheres. They found that each section of the area accounts for a body part upside down (i.e. the top of the area controls the feet). However, ‘a disproportionate amount of space is allocated to the area controlling the hands and mouth’ (Aithchison, 1998), showing that it must allow us to use precise movements in both sign language and spoken communication.

Broca’s Aphasia

If people have brain damage in ‘broca’s area’ (left frontal cortex in the left hemisphere) they are very unlikely to have the ability to produce utterances normally. For example, many people with this problem speak very slowly and ungrammatically (i.e. many drop the –ed ending in English verbs).

However, some people are able to retain this grammatical information and production ability. This shows that even though it is incredibly likely that Broca’s area is related very closely to language, there may be other areas in the brain with similar functions.

Wernicke’s Aphasia

Carl Wenicke located another area in the brain, located in the left temporal lobe. If patients have Wernicke’s aphasia, they usually produce grammatically correct sentences, however include made-up words that often do not fit. Therefore, this area may be responsible for the retrieval of words and linguistic memory.

Future of Brain Imaging

Some theorists believe that various areas of the brain will be found to be responsible for language. For example, Chomsky’s LAD (Language Acquisition Device) which may give children an expectation of language and grammar though linguistic universals and therefore hastens the learning process. However, no such area has currently been found.

Further reading:

Aitchison, J. (1997) The Articulate Mammal: An introduction to Psycholinguistics. Abingdon: Routledge

Yule, G. (1985) The Study of Language. Avon: Bath Press

Pinker, S (1994) The Language Instinct. London: Penguin books Ltd.

Carter, R (2010) Mapping the Mind. London: Orion books Ltd.