Neurobiological Aspects of Language Development in Children - Essay Example

?Raleigh1 Stephanie Raleigh 3rd Dec Neurobiological aspects of language development in children Language acquisition in infants’ life is a major developmental milestone. In most of children, language development occurs rapidly in an effortless task while in others it may fail to develop normally even in the absence of physical, emotional, social or general intellectual impairment .Such children are said to have specific language impairment (SLI) and they manifest varying levels of language understanding and production problems during activities such as speaking, reading and listening (Neville and Bavelier).Language impairment is characterized by deficits in vocabulary, grammatical , morphology, semantics and syntactic (Adams and Gathercole).Children with developmental disorders of language have also been shown to have poor phonological memory skills (Adams and Gathercole).The ability to talk , listen , write and read is very important as it ensures that discoveries and knowledge accumulated by one generation are passed on to the next generation (Laura). Understanding of physiology of language has been achieved through observing the effects of brain lesions on other peoples’ behavior and also through studies done using imaging techniques. Aphasia is the most common speech disorder which is caused by brain damage and is characterized by difficulties in speech production or understanding .Neurobiology of language development is a function of the left cerebral part of the brain (Neville and Bavelier).The left hemisphere consists of parts such as Broca’s area, Wernicke’s area and also angula gyrus. This does not mean that the right hemisphere does not have a role to play in language development, as Raleigh 2 damage of right hemisphere of brain leads to difficulties in reading maps, seeing spatial relations, recognizing complex geometrical forms, problems associated with recognizing narrative, collecting and assembling what they want say (Laura).The right hemisphere is also involved in expression and recognition of emotion in one’s tone. Therefore, both hemispheres are important in language development (Laura; Neville and Bavelier). Speech production Broca’s region which is the inferior frontal lobe is important in planning and executing speech. Its damage and the surrounding regions of frontal lobe and the subcortical white matter leads to disrupted speaking ability and it causes a condition called aphasia , a disorder which is characterized by slow, laborious and non fluent speech .A person with this disorder has thoughts to express but the frontal lobe damage makes it difficult to articulate them. Such people find it difficult to say some words (function words) such as a, the, in, about and they find it easy to say word which convey information (content word) such as nouns, adjectives, adverbs and verbs. They also understand speech much better than they can produce it (Laura). Broca’s region has motor memories such as neurons of sequences of musculature movements that are essential to articulate words as talking involves rapid movement of tongue, jaws, and lips. Such movements should be coordinated with those of vocal cord for taking to occur (Laura).Broca’s asphasia is associated with disorder such as agrammatism even though this condition can occur on its own. Raleigh 3 Anomia is another speech disorder which is observed in Broca’s aphasia .It is characterized by word finding, articulation difficulties and mispronouncing of words. Generally all aphasic people either omit or use inappropriate words. Anomia is symptom in all aphasic conditions (Laura). Speech comprehension Comprehension of speech starts with auditory system which first detect and analyze sounds .A person my recognize sounds and fail to identify or understand its meaning as this involves additional information retrieval from the memory. Speech development is a function of Wernicke’s area of brain which is found at the junction of superior temporal lobes and parietal lobes (Naville and Bavelier). People with Wernicke’s aphasia have a poor speech understanding and production of meaningful speech. They have a fluent speech and they do not strain in articulating words as in the case of Broca’s aphasia. They also employ the use of complex verb tenses and subordinate clauses. Testing their ability to understand speech is achieved by requesting them to use non verbal responses (Laura). Raleigh 4 Damage of Wernicke’s area and auditory region causes pure word deafness in people and this is characterized by ability to hear ,speak and write but the person cannot understand the meaning of such words (Laura).Another symptom of Wernickle’s aphasia is transcortical sensory aphasia which is observed as the failure to understand the meaning of words and also inability to produce a melodic speech .It occurs due to damage of Wernicke’s area and the surrounding region such as occipital, parietal lobes and temporal lobe area which are collectively called as the posterior language area (Laura). Understanding of reading In reading two processes are involved. These processes are recognition and sounding out letter by letter. Processes of reading There are a number of reading processes. They include, whole reading which occurs when one is familiar with the words and therefore it becomes easier to recognize and sound them. Phonetic reading is used for unfamiliar words and involves individual letter recognition and knowing of sounds. Dyslexia is a disorder in which a person has difficulty in reading words and there are various types of dyslexias. Acquired dyslexia occurs in those people who already know how to read and have brain damage, while developmental dyslexia is a reading difficult which is seen in those children who are learning to read. Three types of acquired dyslexia have been identified and they are: surface, phonological and direct dyslexia. Raleigh 5 People with surface dyslexia make errors that are due to words’ visual appearances and pronunciation rules and not because of word meaning (Carson).They also do not recognize word but they sound them .It is also easier for them to read regular words than irregular one (Carson). For those with phonological dyslexia, they find it easier for them to read whole words but they cannot sound words out. Phonological reading is a function of temporoparietal cortex and inferior frontal cortex while word reading is a role of fusiform cortex which is activated by actual words (Carson) while syntactic processing is a function of the left perisylvian cortex (Laura). On the other hand, direct dyslexia is analogous to transcortical sensory aphasia and the only difference is that children with this disorder can only read and sound words but they cannot understand the meaning of such words (Carson). Understanding writing Lack of knowledge about word and the syntactic structure they form, leads to writing disorders such as dysgraphia which in most cases is coupled with dyslexia. There are many writing disorders and some of them are due to lack of motor control. They include inability to write letters and not numbers, ability to write only consonants and inability to place numbers in orderly fashion especially on page (Carson).So many regions of brain are involved in writing. Brain damage that produces aphasia will also lead to speech and writing impairments. Loss of motor control in writing is due to damage of dorsal parietal lobe and promoter cortex and these regions are activated when one is writing. Raleigh 6 Ability to write is related to audition where children first learn the words’ sound and how to read out .The second way of writing, is by first changing the words into mental image before writing. This is phonetic writing is impaired by damage of insula, Broca’s area and ventral precentral gyrus parts of brain. This leads to a disorder called phonological dysgraphia (Carson). Orthographic dysgraphia is another disorder which is visually based and people with it can write pronounceable non words and spell out regular words. They also have difficulty in spelling out irregular words such as busy. This disorder is due to damage of VWFA in the left fusiform gyrus. On the other hand, developmental dysgraphia is a disorder that has biological basis and is characterized by a person having the ability to spell out regularly spelled words and difficulties in spelling out irregularly spelled out words. Such people also have difficulties in word sequence recognition and they make spelling errors (Carson). Scans of brains of people suffering from dyslexics have shown reduced activation of occipototemporal cortex, left temporoparietal and VWFA. There is also high activation of Broca’s area and the left inferior frontal cortex. Perhaps the activation of Broca’ as area is to help in decoding of incomplete information which is being relayed from posterior brain regions, which are involved in reading and which is functioning poorly (Carson). Williams’ syndrome (WMS) is rare genetic disorder which is characterized by hypercalcemia, delayed language, motor development, altered facial expression, abnormal or unusual sensitivities to types of sounds and language processing difficulties (Bellugi et al). Raleigh 7 The most common feature of WMS is mental retardation. Its mode of transmission is mostly likely to be autosomal dominant with most cases showing new mutations (Belluji et al). Works cited Adams, A.M and Gathercole, S.E. "Limitations in working memory implications for language development." Int.J. Lang.comm.Dis 35.1 (2000): 95-116. Web. 3 Dec. 2011. Bellugi, U., Lichtenberger, L., Jones, W. and Lai, Z. "The neurocognitive profile of williams syndrome:A complex pattern of strengths and weaknesses." Journal of Cognitive Neuroscience. 12:Suppliment (2000): 7 - 29. Web. 3 Dec. 2011. Carson, R.Neil. "Human communication." Foundations of behavioral Neuroscience. 8 th ed. Boston: Prentice Hall, 2010. Print Laura, E. Berk. Infants, Children and Adolescent. 6th ed. Allyn and Bacon, 2007. Print Neville, H.J and Bavelier, D. "Neural organization and plasticity of language." Current opinion in Neurobiology 8 (1998): 254-258. Web. 3 Dec 2011. Read More