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Bilingualism and Brain Changes /Introduction

In the recent years, the issue of bilingualism and brain changes has raised debates all over the world. Initially, the topic was investigated using animals such as rodent and revealed that there were structural adaptations that result to exposure for instance to a second language. Recently, many people are becoming bilingual globally provoking researchers to identify the relationship between bilinguals and the brain structure some of the common arguments that have been raised include that bilingualism leads to thickening of the cortex, increased grey matter and better white matter among the bilinguals. The issue of bilingualism has also lead to many other questions such as what is bilingualism, how do children acquire bilingual languages, and how the brain and mind accommodate the presence of the two languages. Others issues that have come up include the cognitive advantages of the bilingualism, the consequence of competition and parallel activity across the two languages of a bilingual and the neural basis of the bilingual effect in conflict resolution.

/Definition of bilingualism There is no commonly agreed definition of bilingualism; however, according to Hernandez & MacWhinney (2005), bilingualism can be defined as the use of more than one language by an individual. Bilingualism is a fluctuating system in both children and adults where the proficiency and use of two languages may change depending on the exposure to other speakers of the languages and opportunity to utilize the languages (Hernandez & MacWhinney, 2005). Bilingualism is an ideal and is a dynamic process across numerous domains such as tasks, time, experience and topics. The degree of bilingualism varies from one person to another. In addition, it is not necessary for bilingual individuals to be perfectly fluent in the two languages and at times, there may be a dominant language. There are different types of bilinguals such as late sequential bilingual, early sequential bilingual, simultaneous bilinguals. Late sequential bilinguals a person who has been speaking one language in their home country but moves to another country and starts speaking a different language. Simultaneous bilingual refers to a person who has learned two languages since birth while the early sequential bilingual refers to a person who uses a certain language at home and then learns another form school which is mostly a community language (Hernandez & MacWhinney, 2005).

/Bilingual Child Language Acquisition The acquisition of language by bilingual Children from infancy can be classified into three broad stages. First, the child possesses a single lexical system, which contains words from both languages (Volterra, & Taeschner, 1978). Secondly, the child recognizes two different lexicons, but they apply similar syntactic rules for the two languages (Volterra, & Taeschner, 1978). Thirdly, the child acquires two linguistic codes containing different lexicon and syntax, but the child exclusively associates each language with people who use that language (Volterra, & Taeschner, 1978). After successful completion of this stages when a child can effectively communicate with a given without categorizing people in terms of the language they speak, then a child can be termed as bilingual (Volterra, & Taeschner, 1978).

/ Brain Accommodation of Two Languages The presence of two grammatical systems in bilinguals may lead to convergence or conflict of the two systems (Kroll, & Bialystok, 2013). Hence, the brain and the mind have to adapt during word processing and sentence structuring in order to accommodate the two systems. Consequently, when similar principles are used, the two languages gain access to the shared grammatical processes (Kroll, & Bialystok, 2013). The reliance on similar principles using syntactic priming allows priming across languages, which is identical to priming within languages. Hence, when similar structures are used, there is no prevention of reliance on shared representation by switching from a language to the other from prime to target sentence (Kroll, & Bialystok, 2013). In cases when there use of conflicting or different structures by the two languages of bilinguals, daily exposure to the second language gives rise to strategies recruited by bilinguals during syntactic ambiguity resolution since parsing decisions are dynamic (Kroll, & Bialystok, 2013). Presence of two languages in the brain provides a lens into how the cognitive systems interact that is not visible with bare eyes. The bilingual language is dynamic and changing language at will is not possible. The cross-language interactions that exist are evident at every level of language processing such as grammatical structures shared among languages (Kroll, & Bialystok, 2013). There are various levels of bilingual language control and cognitive control, and various neural devices are responsible for cognitive control. This control is as a result of the integration of the neural systems such as the basal ganglia, anterior cingulate cortex, inferior parietal lobule and the prefrontal cortex. Each part of the brains is responsible for a different cognitive control aspect (Kroll, & Bialystok, 2013). Cognitive control refers to the processes that relate to temporal sequencing and selection of the sequences rather on the representation of the language (Kroll, & Bialystok, 2013). When the bilinguals are producing words, cognitive control is usually at work to ensure correct selection of the right lexical item of the intended language and to avoid interferences from non-target language, which is achieved through the interplay of the anterior cingulate cortex, inferior parietal cortex, prefrontal cortex and basal ganglia (Kroll, & Bialystok, 2013). The anterior cingulate cortex together with the basal ganglia modulate the activities in the left prefrontal cortex resulting to usual modulatory influence on the inferior parietal cortex and left prefrontal cortex which are the systems responsible for mediating word production (Kroll, & Bialystok, 2013).

/Cognitive Advantages of Bilingualism Bilingual improves the efficiency and the development of the multifactorial executive control system of the brain (Bialystok, 2007). Since the bilingual brain handles two languages at the same time, it, therefore, develops the skills for various functions such as working memory, switching language (Bialystok, 2007). It also assists in inhibition or the discarding of irrelevant stimuli using the cognitive inhibition mechanism. These three skills; inhibition, working memory and switching language are the main components of the executive control which is responsible for sustaining attention, high level thought and multitasking (Bialystok, 2007). Since bilingual individuals are able to switch between languages, they are also efficient in switching between tasks even those that do not relate to language at all (Bialystok, 2007). In addition, bilingual people respond better to situations when the brain monitoring system is not taxed than the monolingual individual (Bialystok, 2007). They also tend to do better in tasks related to spatial working memory than the monolinguals (Bialystok, 2007). Bilingualism also has differing effects on the structural and the functional properties of certain subcortical and cortical brain structures. For instance, various studies have proven that bilingual individuals have grey matter with a higher density (Bialystok, 2007). Similarly, older bilingual individuals have been found to possess white matter in their brain that is better maintained than the monolingual individuals are. However, bilingualism does not necessarily make an individual smarter, and there is no connection between bilingualism and aspects such as intelligence quotient, executive intelligence or emotional intelligence (Bialystok, 2007). Bilingualism leads to better cognitive reserve in the older people. For instance, bilingual individuals who have Alzheimer disease has been found to function at the same level as the brain of monolingual individuals within the same age bracket who have not suffered any kind of brain degeneration (Bialystok, 2007). Further, for bilingual individuals, the onset of dementia symptoms is delayed significantly as compared to those who are bilingual (Bialystok, 2007). The delay can be up to five years. This is because the bilingual people take part in mental activity or stimulation of physical activity constantly, which is crucial in maintaining the cognitive function hence delaying the onset of symptoms in people with dementia (Bialystok, 2007).

/Consequence of Parallel Activity and Competition across the Bilingual’s Two Languages The two languages of the bilingual individuals are always active despite the requirement or the intention of the person to use a single language; consequently, there is competition between the two languages and the individuals juggle the competition resulting from the need to select a language continually when one must be selected (Hernandez & MacWhinney, 2005). The parallel activities of the two languages of a bilingual person can be evident in different situations such as when the person is reading, when preparing to speak a single language alone and when listening to speech (Hernandez & MacWhinney, 2005). Therefore, the brain has to possess the code switching ability, which demonstrates that these individuals have an exquisite mechanism of cognitive control (Green, & Abutalebi, 2013). The control processes ensure controlled use of each language hence enabling perfect performance of the other language. Some of the control processes are the inhibition of the most dominant language that has enduring consequences of native use (Green, & Abutalebi, 2013). The brain of bilingual individuals can inhibit the unrequired language once it is activated at a time when it is not required (Hernandez & MacWhinney, 2005). Further, they can selectively attend to critical information, which signals the status of the language (Hernandez & MacWhinney, 2005). The same neural tissue supports the functioning of both languages of a bilingual. Therefore, according to Hernandez & MacWhinney (2005), differences in the brain activity while using two languages result from the requirement to use control mechanisms that can enable the engagement of the less dominant language and control the use of the dominant one (Green, & Abutalebi, 2013). Hence, areas of the brain that control the language usually overlap with those that control the cognitive functioning occasionally (Green, & Abutalebi, 2013). The ability to switch from one language to another and the ability to switch between tasks not related to linguistics use the same cognitive control mechanism. Similarly, multilingual individual speaking more than two languages and those speaking only two languages follow similar parallel activation patterns and control mechanisms where the relative effects of these languages are determined by the dominance and proficiency of the language (Hernandez & MacWhinney, 2005). In addition to control areas of the brain being activated in non-linguistic and linguistic tasks, Bilinguals make use of the control networks efficiently than their monolinguist counterparts even in purely cognitive tasks. Further, during non-verbal conflict monitoring tasks, both monolinguals and bilinguals use anterior cingulate cortex, but bilinguals are more efficient and require reduced activation to solve equal level of conflict. Also, bilinguals contain cognitive consequences beyond factors such as socioeconomic status which may influence cognition (Green, & Abutalebi, 2013). Bilingualism has no significant advantages on the younger people, but in older people, there are both neural measures sand behavioral measures. Hence, the brain activation patterns in older people allow them to resolve a conflict easily than the monolinguist (Hernandez & MacWhinney, 2005). Bilinguals are able to effectively negotiate the parallel activities of the languages spoken and manage to speak in one language when required to do so and code switch efficiently with other bilinguals. According to Green & Abutalebi (2013), bilinguals often find themselves in a continuum between a monolingual mode where one language is a dominant and bilingual mode where both languages can be actively used. Even during monolingual mode, individuals experience parallel activation of the two languages in order the attenuation of each language to achieve total monolinguist in difficult (Green, & Abutalebi, 2013).

/The Neural Basis Of The Bilingual Effect In Resolving Conflict Bilinguals have the ability to switch the anterior cingulate cortex in order to monitor conflict. Further, lifelong bilingualism ensures neural efficiency for cognitive control in old age (Gold et al., 2013). The task costs of switching increase with age and hence older bilinguals do better than their monolinguist counterparts (Gold et al., 2013). The anterior cingulate cortex is associated with better conflict resolution among bilinguals (Teubner-Rhodes et al., 2016). Since bilinguals are better in executive function and attentional control than monolinguals, they are advantaged than the monolinguals in conflict resolution (Gold et al., 2013). Additionally, bilingual individuals are efficient in alerting of executive control networks as well as fast in performing tasks. They are also able to present alerting cues and better in the resolving of conflict information, and their switch cost is far much reduced as compared to monolinguals (Teubner-Rhodes et al., 2016).Further, bilinguals have an added advantage over monolinguals on the test of cognitive controls due to the ability to manage two competing languages constantly (Teubner-Rhodes et al., 2016). Also, most of the brain networks used for cognitive control are used in language control which aids in conflict resolution (Teubner-Rhodes et al., 2016). However, different conflict relies on different neural mechanisms to process the conflict. There is heightened activation in the inferior cortex which is involved in response inhibition as well as in the superior parietal cortex and caudate which is directly connected with language selection and control (Gold et al., 2013). The anterior cingulate cortex is the bridge between stimulus-response and stimulus-stimulus conflict resolution as well as between cognitive control and language due to the frequent use of the area by bilinguals in conflict resolution (Teubner-Rhodes et al., 2016). Each language processing aspect imposes different cognitive demands hence creating different bilingual cognition profiles (Gold et al., 2013). Various bilingualism forms may tune the neural networks, which support language use differently. Some bilingual’s codes have the ability to switch cues frequently while some do not (Teubner-Rhodes et al., 2016). Similarly, shared language forms exist among languages and bilinguals can comfortably negotiate higher competition level in daily the use of language than monolinguals (Gold et al., 2013).

/Conclusion The topic of bilingualism and brain changes has attracted the attention of many researchers in the recent years. However, the researcher has not yet come to a consensus on the definition of the word bilingualism indicating that bilingualism is an ideal and is dynamic. Among children, the acquisition has been found to go through various stages before the child is termed as bilingual. The brain has also been found to go through various structural changes and adaptations in order to accommodate the presence of these languages. Some of the cognitive advantages of the bilingualism are the excellent ability in switching between tasks and performing spatial tasks, improved brain structures and better cognitive reserve and learning. The consequence of parallel activity and competition across the two languages of a bilingual is that the juggling results to the need to negotiate the competition across the two languages hence controlling each language and allowing fluent performance. Control processes such as inhibition of the dominant language also aid in perfect language performance. The neural basis of bilingual effect in conflict resolution is through tuning of the anterior cingulate cortex by bilinguals for conflict monitoring.

/References Bialystok, E. (2007). Cognitive effects of bilingualism: How linguistic experience leads to cognitive change. The International Journal of Bilingual Education and Bilingualism, 10 (3), 210-223 Gold, B. T., Kim, C., Johnson, N. F., Kryscio, R. J., & Smith, C. D. (2013). Lifelong bilingualism maintains neural efficiency for cognitive control in aging. Journal of Neuroscience, 33(2), 387-396. Green, D. W., & Abutalebi, J. (2013). Language control in bilinguals: The adaptive control hypothesis. Journal of Cognitive Psychology, 25(5), 515-530. Hernandez, A., Li., P., & MacWhinney, B. (2005). The emergence of competing modules in bilingualism. Trends in Cognitive Sciences, 9 (5), 220-225 Kroll, J. F., & Bialystok, E. (2013). Understanding the consequences of bilingualism for language processing and cognition. Journal of Cognitive Psychology, 25(5), 497-514. Teubner-Rhodes, S. E., Mishler, A., Corbett, R., Andreu, L., Sanz-Torrent, M., Trueswell, J. C., & Novick, J. M. (2016). The effects of bilingualism on conflict monitoring, cognitive control, and garden-path recovery. Cognition, 150, 213-231. Volterra, V. & Taeschner, T. (1978). The acquisition and development of language by bilingual children. Journal of Child Language, 5 (2), 311 –326.