The critical age hypothesis, or the theory that fluent acquisition of a language can, for the most part, only occur before puberty, makes the issue of childhood aphasia more and more interesting to the scientific community. The idea of a critical age supports the hypothesis of lateralization: that the later a second language is learned in an individual’s life the more likely it is to be at least partially stored in the right hemisphere.
This hypothesis is corroborated by early work done by Dr. Joy Hirsch at Memorial Sloan-Kettering Hospital in Seattle, in which she found through MRI scans that bilinguals who acquired both languages in infancy had only one Broca’s area for both languages, whereas bilinguals who learned their second language later in life seemed to have two distinctive areas that functioned like the Broca’s area (Blakeslee, 1997). Both the critical age and the different cognitive strategies used in language learning could account for this. Blakeslee uses the example of an English-speaking high-school student learning Russian for the first time to demonstrate Hirsch’s findings as a corroboration of the critical age and of hemispheric lateralization. This high-school student has developed their Broca’s area to produce English, but has to develop new skills in order to pronounce the phonemes of another language. Because of this a second area that functions like the Broca’s area may form, sometimes in the right hemisphere depending upon the strategies used in language learning.
This hypothesis is corroborated by early work done by Dr. Joy Hirsch at Memorial Sloan-Kettering Hospital in Seattle, in which she found through MRI scans that bilinguals who acquired both languages in infancy had only one Broca’s area for both languages, whereas bilinguals who learned their second language later in life seemed to have two distinctive areas that functioned like the Broca’s area (Blakeslee, 1997). Both the critical age and the different cognitive strategies used in language learning could account for this. Blakeslee uses the example of an English-speaking high-school student learning Russian for the first time to demonstrate Hirsch’s findings as a corroboration of the critical age and of hemispheric lateralization. This high-school student has developed their Broca’s area to produce English, but has to develop new skills in order to pronounce the phonemes of another language. Because of this a second area that functions like the Broca’s area may form, sometimes in the right hemisphere depending upon the strategies used in language learning.
Treatment for Bilingual Children
Traumatic brain injury often brings with it a difficulty in learning new information, a difficulty that most markedly impacts children. As explained by speech-language pathologist and University of Missouri lecturer Barbara Brinkman, adults have a lifetime of learning experience that they may not have completely lost after injury, whereas a child's brain has not yet been fully developed. "A child has had fewer opportunities to learn, and they're going to have trouble learning all the new things that are coming up in school [because of the language and cognitive deficits caused by traumatic brain injury]," Brinkman explains, emphasizing the increased vulnerability of the child brain compared to the adult brain (MUSHPWeb1, Youtube, 2011).
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Using the child's first language in therapy generally facilitates the re-acquisition of the second language (Thordardottir, 2010, p. 524). This focus on the first language is important in children: it promotes a trusting relationship between the child and the speech therapist. However, if the child has a language control impairment, more progress has been noted with therapy in the child's second language (Ansaldo & Saidi, 2014, p. 3).
Switching between the L1 and L2, or code-switching, is a natural quality of bilingual individuals, and should not be rejected in therapy. In the past, this was often thought of as the child mixing up their two languages, resulting in increased advocacy for separate treatment of L1 and L2. However, the understanding of how both languages coexist in the child's life is crucial to integrating them back into their former life: code-switching has been shown to help children understand pragmatic context, which is a skill that is often greatly disrupted by traumatic brain injury (Thordardottir, 2010, p. 529).
Switching between the L1 and L2, or code-switching, is a natural quality of bilingual individuals, and should not be rejected in therapy. In the past, this was often thought of as the child mixing up their two languages, resulting in increased advocacy for separate treatment of L1 and L2. However, the understanding of how both languages coexist in the child's life is crucial to integrating them back into their former life: code-switching has been shown to help children understand pragmatic context, which is a skill that is often greatly disrupted by traumatic brain injury (Thordardottir, 2010, p. 529).
Recovery
Younger patients with aphasia generally show a better prognosis of recovery than older patients due to the negative correlation between age and neuroplasticity. Though comprehension often improves more than output of speech, children often show remarkable rates of recovery. However, severe cases of traumatic brain injury in children often lead to chronic language disorders over the course of the lifetime as their brain continues to develop (Liégeois et al., 2013, p. 388). The broad goal of child language recovery is to allow the child to connect with family and to reintroduce them into the school system with the hope that a return to normal life and daily access to language output will assist in the recovery process over a period of years. According to neuropsychiatrist Keely Deidrick, PhD, when a child with traumatic brain injury is reintegrated into the school system they are oftentimes given quiet, separate places to do work or given "rest breaks" during class time in order to reduce overstimulation (MUSHPWeb1, Youtube, 2011). Slowly integrating the child back into their former life allows them to achieve a sense of normality and gives them contextual opportunities to reacquire and relearn aspects of language that they may have lost.
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