The Human Brain and Language - Research Paper Example

? Second Language Acquisition: The Adult Brain Versus The Child Brain Elaine M. Smith A major phenomenon that separates humans from all other animals on the planet is the ability to communicate using spoken language. People who are proficient in two languages are categorized as being bilingual. There is much debate centered on the appropriate time in a person’s life of when to begin learning a second language. Neuroscience perhaps is the best field to resolve this debate. Through the use of neuroimaging techniques, neuroscientists have the ability to identify the structures of the brain involved in primary and second language acquisition. Their studies and experiments show that there is in fact a critical period of brain development in which it is optimal to begin learning a second language. This critical period is based on the plasticity and continuing myelination of a prepubescent child. Neuroscience experiments and studies have also demonstrated that learning a second language at an early age does not hinder proficiency and development of the primary language nor are bilingual children less proficient in the primary language as monolingual children. In fact the exact opposite appears to be true. Furthermore, learning a second language appears to be associated with positive benefits for the brain. In order to capitalize on these positive benefits and achieve high proficiency and fluency, second language acquisition should begin as early in life as possible. The Human Brain and Language The human brain differs from that of other species in that the human brain has regions dedicated to language comprehension and production alone. For the majority of people, these regions are located in the left hemisphere. However, in about 20 percent of left-handed individuals, these language regions are located in the right hemisphere. This localization of language ability to predominately one hemisphere of the brain is referred to as lateralization. Often times, language function shifts to the right hemisphere when an injury occurs to the left hemisphere early in life during childhood (Moddel, Lineweaver, Schuele, Reinholz, & Loddenkemper, 2009). The Language Areas of the Brain Language processing occurs mainly in Broca’s and Wernicke’s areas. In general terms, words are comprehended by Wernicke’s area and articulated by Broca’s area. Broca’s area is located in the frontal lobe. The back region moves the mouth to form words, while the front part is hypothesized to be related with aspects of word meaning. Wernicke’s area is located in the upper temporal lobe adjacent to the occipital and parietal cortices. In this area, heard and seen words are understood and selected for articulation. A thick band of tissue known as the arcuate fasciculus connects Broca’s and Wernicke’s areas. An area known as Geschwind’s territory surrounds Wernicke’s area. This territory is located in the lower part of the parietal lobe. Here information from sound, sight, and body sensation come together. When a person hears words spoken, Wernicke’s area matches the sounds to their meaning, and special neurons in Geschwind’s territory assist by combining the different properties of words to provide comprehension. When a person speaks, the process happens in reverse. Wernicke’s area finds the correct words to match the thought that is to be expressed. The chosen words then pass to Broca’s area via the arcuate fasciculus. Broca’s area then turns the words into sounds by moving the tongue, mouth and jaw into the required position and by activating the larynx. Aphasias Identification of these language areas resulted from studying patients who suffered brain injuries in these general areas and as a result of their injuries, presented deficient language comprehension and production symptoms. Traumatic brain injuries and strokes can lead to aphasia, which is the loss of the ability to produce and/or comprehend language. Aphasia is usually associated with a brain injury such as a stroke, which affects the brain’s language areas. Depending on the type of damage, the area affected, and the extent of damage, those suffering from aphasia may be able to speak yet have little or no comprehension of what they or others are saying. Or they may be able to understand language, yet be unable to speak. There are six principle types of aphasia, each of which involves injury to a certain area of the brain. Many of these aphasias are caused by strokes. Production aphasia – This is caused by damage to Broca’s area. It is classified by the inability to articulate words or string them together. If words can be uttered, they tend to be verbs or nouns with abnormal tone and rhythm. Conduction aphasia – This is caused by damage to the link between Wernicke’s and Broca’s areas. It is categorized by speech errors to include substituting sounds. Speech comprehension, however, is good. Transcortical motor aphasia – This is caused by damage around Broca’s area. It is categorized by good comprehension with nonfluent speech. Speech is often limited to two words at a time. Suffers retain the ability to repeat words and phrases. Transcortical sensory aphasia – This is caused by damage to the temporal-occipital-parietal junction. It is categorized by the inability to comprehend, name, read, or write, however, the ability to recite previously learned passages remains intact. Global apashia – This is caused by widespread damage in the brain. It is categorized by general deficits in comprehension, repetition, naming, and speech production. Automatic phrases such as counting may be spared. Sensory aphasia – This is caused by damage to Wernicke’s area. It is categorized by the inability to understand language. It is often combined with general comprehension problems and a lack of awareness of one’s own deficiency (Carlson, 2011). The Multilingual Brain Being fluent in two or more languages, particularly from early childhood, enhances various cognitive skills and might also protect against the onset of dementia and other age-related cognitive decline. One reason for this may be that speaking a second language builds more connections between neurons. Studies show that bilingual adults have denser gray matter, especially in the inferior frontal cortex of the brain’s left hemisphere, where most language and communication skills are controlled. The increased density was most pronounced in people who learned a second language before the age of five (Diamond, 2010). This means that acquiring more than one language is helpful in the development of the person’s own brain. Neuroscience of Second Language Acquisition Infant’s/Child’s Brain and Bilingualism Adult’s Brain and Bilingualism – Late in Life Learner Language learning and processing components of brain decline their ability with the passage of time (Birdsong). These declines are linear and their proportion increases with the age (Birdsong). However, second language use is less efficient than first language (Birdsong). As the demands from finite capacity functional system of brain increases, the performance declines are reported (Birdsong). So, processing deficits are more reported in use of second language as compared to first language (Birdsong). Biologically, due to contraction of frontal lobe and pre frontal cortex with the increasing age decline the capacity of brain and memory retaining ability (Birdsong). In the same way dopamine declines also cause loss of ability to learn a second language at a later age (Birdsong). There are both endogenous and exogenous ways responsible for the decreased ability to learn a second language at a later age (Birdsong). The factor of nativeness is also important; the native languages have more probability of being learned easily as compared to non native ones (Birdsong). The outcome of second language acquisition (L2A) among adults is evidently unlike the results of first language acquisition (L1A) among children. Apart from this basic observation, researchers make efforts to comprehend a mixture of sources of age-related effects in L2A. (Birdsong). Researchers have investigated a number of biographical variables that can be found to predict L2A outcomes (Birdsong) . Age of acquisition is said to be the age at which learners are engrossed in the L2 situation, normally like immigrants (Birdsong). This concept is different from age of first contact or exposure which can take place in a formal schooling or teaching atmosphere, visits to the country with a second language, comprehensive contact with relatives who are users of the second language, and so on (Birdsong) Language is an important source of communication for humans that separates them from social isolation and increases their social interaction (PHILLIPS, 2011). There is an increased population of adult bilinguals and their processing mechanisms are different from young bilinguals (PHILLIPS, 2011). Language selection is more common in youngsters but less common in older adults (PHILLIPS, 2011). Literature says that there is a language non selective process which is associated with young age bilinguals and there are variations in language processing systems in older and young age (PHILLIPS, 2011). There are age related differences in understanding of both the native language and the second language (PHILLIPS, 2011) .In other words, learning a second language becomes difficult at a later age and is easier to be taught to child. At a younger age, human mind is more receptive to receive language knowledge and grasp and comprehend it. There is a difference in the behavioral and neural process in monolingual and bilingual people (Ioulia Kovelman, 2008). Early bilinguals are more proficient in languages as compared to adult bilinguals (Ioulia Kovelman, 2008). The young monolinguals have more language processing activity as compared to older people (Ioulia Kovelman, 2008). Human neural organization and language processing capacity can be molded by extensive dual-language exposure early in life (Ioulia Kovelman, 2008). Language-dedicated neural tissue can be modified to learn two languages early in life as compared to later years (Ioulia Kovelman, 2008) Age of the first bilingual teaching plays a very important role in understanding two languages. (Petitto, 2009). At an early age, there is a sensitive period for learning a new language (Petitto, 2009). Dual language proficiency is more at an early age (Petitto, 2009). Early age bilanguage masteyt has positive impact on child’s development and its other aspects (Petitto, 2009). Children who get early and systematic exposure to both languages, they are good at grasping the fundamentals of both the languages in the same manner as they can learn it while learning one language (Petitto, 2009). There were concerns that children learning two languages can be at a disadvantage as compared to those who learn only one. But research shows that bilingualism gives no disadvantage, rather those youngsters are at advantage as early lingual reading and skill acquisition (Petitto, 2009). Linguistic functions are more differentially lateralized in bilingual brains as compared to multi lingual brains. (Alice Mado Proverbio, 2002). Age is another important factor for activation of brain for native as well as second language (Alice Mado Proverbio, 2002). When both languages are acquired at early age, their processing takes place in frontal cortical areas of brain, however at later age it is processed in another area (Alice Mado Proverbio, 2002). The language proficiency of early and late age bilinguals is different (Alice Mado Proverbio, 2002) Fluent bilinguals are able to understand and separate both languages easily (Rodriguez-Fornells, 2005). Also, they have tendency to switch to use one language in place of other (Rodriguez-Fornells, 2005). However, this code switching depends upon the target activation of brain which varies with age, being more active at a younger age (Rodriguez-Fornells, 2005). Bilingual children’s control mechanisms are greater than monolingual children as they have more switching and attentional control demands from early on (Rodriguez-Fornells, 2005). Bilingual children are exceptionally good at ignoring distractive mechanisms and switching between different cognitive tasks (Rodriguez-Fornells, 2005). Literature says that younger the child is at the time of acquiring a language, the more the probability is that he will achieve native pronunciation and proficiency (Kennedy, 2006). New born and young minds are the brains with unlimited potential so it is advisable to teach the two languages at an early age as compared to a later age (Kennedy, 2006).this receptiveness of brain is from one to 10 years of age of child (Kennedy, 2006). So, this is the critical period of a child learning two languages (Kennedy, 2006). After the age of six, the ability of acquiring a second language declines (Kennedy, 2006). After that brain plasticity decreases and brain is less able to understand and process the other language (Kennedy, 2006). Monolinguals and late bilinguals show left brain activeness whereas early bilinguals show reliable bilateral hemispheres involvement (Vaid, 2006). At a certain age, the second language is acquired with the same proficiency (Vaid, 2006). Because of the neural plasticity, an early exposure to bilinguism is more effective as compared to at a later age (Vaid, 2006). Right as well as left hemisphere of brain is involved in processing and understanding of languages, however at a later time in life, right brain’s effectiveness declines due to which a person cannot successfully master a second language at a later age (Vaid, 2006) late bilinguals are mostly similar to monolinguals in their processing activities of brain, however early bilinguals are more proficient and active at second language (Vaid, 2006) Second language acquisition is related to processing to right hemisphere areas of brain.(Susanne Reiterer, 2009). In weak and less proficient speakers right hemisphere areas are more involved whose functioning decrease with the increasing age (Susanne Reiterer, 2009). A bilingual’s brain is slightly different organized as compared to monolingual, increasing its productivity in earlier age (Susanne Reiterer, 2009). Age of onset is a very important factor in the acquisition of second language. (Susanne Reiterer, 2009). The language proficiency decreases because of the less activation of right hemisphere of brain in adults (Susanne Reiterer, 2009). Different proficiency groups on the basis of different ages have different abilities of understanding and grasping the grammatical processes of second language (Susanne Reiterer, 2009). The acquisition of second /third or fourth language leads to structural and functional changes in brain (Bot, 2005). The density of grey matter is more in early bilinguals and monolinguals (Bot, 2005). There is a highly negative correlation between density if grey matter and age of onset of acquisition of second language (Bot, 2005). There is an increase in density of grey matter with early language learning; however it decreases with the increasing age (Bot, 2005). Second language acquisition at an early age increases the capacity and density of grey matter (Bot, 2005). From new born to 2 to three years, there is continuous increase in functioning of grey matter until it reaches a peak point after which it decreases (Bot, 2005).Until puberty, synaptic density stabilizes and remains the same at older age (Bot, 2005) Human mind has an ability to learn more than one language and learning a second language increases the density of grey matter (J.Wang, 2004). Increase in density of grey matter is more in early than late bilinguals (J.Wang, 2004). This proficiency decreases with the increasing age (J.Wang, 2004). The structure of human brain is altered by acquisition of second language as early bilinguals learn second language as a result of social experiences but not their genetic pre disposition (J.Wang, 2004). Also the age is said to have a great impact on learning both languages. There is a greater probability of seizure onset in early years as compared to late years. (Gabriel Moddel, 2008) Non-identical neural systems intercede each of the languages when the second language is acquired after early years of childhood, however the same brain systems mediate both languages when the second language is attained in infancy or early childhood (Mills, 2006). Process of learning a language greatly impacts on the language related activities of brain (Mills, 2006). The timing also matters a lot in acquisition of second language (Mills, 2006). Early acquisition facilitated the processing systems of brain and at a later age these processing mechanisms decline (Mills, 2006). From all the literature discussed above, it is proved that learning a second language increases the ability of brain and develops better functioning systems. So, it is advisable that a child should be acquainted with two languages early in his life that makes him more able to understand the differences in the usage of two languages. With the increase in age the learning and grasping activity of second language, it is suggested that a child should be acquainted with a second language early in age. Young Brain compared to an Adult Brain Young babies have special abilities for processing phonetic units which are crucial for successful phonological segmentation of words, later learning and language learning (Petitto, 2009). From birth to four months of age, monolingual babies have the capacity to categoricallty discriminate the smallest unit o building block of any language like ba,da. However, when their age becomes 14 month, their discimination capacity is restricted mostly to their native language with precision (Petitto, 2009). So, we can say that at the age of 14 months they lose their universal capacity of understanding any language (Petitto, 2009). Early bilinguals have a phonetic bilingual advantage which means that as compared to monlinguals, bilingual babies have an increased sensitivity to a greater range of phonetic contracts (Petitto, 2009). So, greater bilingual phonetic perception in early life as compared to later in life, gives a competitive advantage to a child and keeps his capacity of discriminating phonetic units open (Petitto, 2009). Similarly, phonological word segmentation is easier for a bilingual baby (Petitto, 2009). Monolingual and bilingual babies have same recruitment and processing for language dedicated neural tissue (Petitto, 2009). For example the Superior Temporal Gyrus, STG, which is responsible for phonetic processing, the Left Inferior Frontal Cortex, LIFC, meant for processing of words, and the primary visual occipital area, V1, which undergoes the sensory processing of nonlinguistic visual checkerboard (Petitto, 2009). There are fascinating brain changes which occurs with the increasing age (Petitto, 2009). Early exposed bilingual adult before the age of 5, processes the languages in the same way as monolinguals (Petitto, 2009). However, later exposed adults have to do more processing and exhibit more neural effort in understanding of a second language (Petitto, 2009). After puberty, the second language acquiring capacity of brain declines (Petitto, 2009). Duing early years of language acquisition, right hemisphere processing is more involoved (Susanne Reiterer, 2009). Because of the more involvement of right brain in language processing in early age, this processing is proved out to be advantageous for the person (Susanne Reiterer, 2009).at this time right brain’s involvement is more than left brain. Left brain’s more involvement starts later on when a person has to gain grammatical sophistication (Susanne Reiterer, 2009). Also the learning style becomes different at later stage of life as compared to when young (Susanne Reiterer, 2009). Even the learning strategies change (Susanne Reiterer, 2009). The activation system of brain varies in adults and causes it to process language differently (Susanne Reiterer, 2009). The right brain activation also declines with increase in age, grammatical method of processing words does not remain the same (Susanne Reiterer, 2009). However past acquaintance with foreign languages is also very important (Susanne Reiterer, 2009). Past experience in other languages is associated with left hemisphere activation (Susanne Reiterer, 2009). Whereas, a reduced amount of exposure to second language is associated with the right hemisphere activation (Susanne Reiterer, 2009) for late bilinguals there is always more variability and less productivity of brain in understanding due to changing functions of brain with age (Susanne Reiterer, 2009). Also the brain of monolingual is different from that of a bilingual because of its processing and functioning ability, because it is more efficient and more active (Susanne Reiterer, 2009). Left hemisphere of brain is involved in processing of language, especially the grammatical aspects of language (Vaid, 2006). In the same way, right hemisphere is also important and it supports language processing (Vaid, 2006). Neural plasticity is present more in early years of age as compared to later years (Vaid, 2006) . The lesser the time between acquiring the two languages will be, the more will be the lateralization between those languages because of almost similar brain processing, maturational and cognitive, mechanisms (Vaid, 2006). The pattern of lateralization is similar for both the languages in early age, which changes with the increasing age (Vaid, 2006) . Therefore, the effectiveness of the second language acquired will depend heavily on age of acquisition. With the increasing age, the second language acquisition requires greater time and effort because of decrease in the neural plasticity of brain (Vaid, 2006) . Those who acquire the second language late in their lives, show a change elative to learning of first language. In the end we can say that human mind changes its structure and function at different stages of life. It is more receptive at a younger age, neural plasticity is more, can process more than one language more efficiently as compared to when it gets older. The more the age is at the time of second language acquisition, the more hard it is and more effort is required to grasp the language and processing of words. Even then it is not sure that the adult will retain the language. The biological differences in the structure and function of brain between children and adults justify this notion that second language acquisition should be made early in order to be effective and long lasting. Also there is strong inclination in literature towards the highly developed and efficient working capability of a bilingual as compared to monolinguals. References Birdsong, D. (2006). Age and Second Language Acquisition and Processing: A Selective Overview. Language Learning, 569-49. doi:10.1111/j.1467-9922.2006.00353.x Conboy, B. T., & Mills, D. L. (2006). Two languages, one developing brain: event-related potentials to words in bilingual toddlers. Developmental Science, 9(1), F1-F12. doi:10.1111/j.1467-7687.2005.00453.x de Bot, K. (2006). The Plastic Bilingual Brain: Synaptic Pruning or Growth? Commentary on Green, et al. Language Learning, 56127-132. doi:10.1111/j.1467-9922.2006.00358.x Carlson, N. R. (2011). Foundations of behavioral neuroscience. Boston, MA: Pearson. Diamond, J. (2010). The Benefits of Multilingualism. Science, 330(6002), 332-333. doi:10.11261/science.1195067 Hull, R., & Vaid, J. (2006). Laterality and language experience. 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