User:Egrund/Neuroscience of multilingualism

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** We are focusing on the bimodal bilingualism sections of this article because they really sparked our interest, and the rest of the article was difficult to add to because it was already pretty dense with information. **

Bimodal Bilinguals- Emily
Bimodal bilinguals are individuals who are fluent in both sign language and oral language. The effect of this language experience on the brain compared to brain regions in monolinguals or bilinguals of oral languages has only recently become a research interest, but is now used to provide insight on syntactic integration and language control of bilinguals. Like other bilinguals, bimodal bilinguals develop fluctuating degrees of fluency in their two languages. Because spoken language is what is predominantly used in most communities, hearing children of deaf parents are often more proficient in their spoken language rather than their sign language. Bimodal second language learners have much in common with learners of a second spoken language, and also many differences. A study conducted by Diane Lillo-Martin, Ronice M. de Quadros, Deborah Chen Pichler and Zoe Fieldsteel considers how the issues around language separation and language mixing are different when studying bimodal bilingualism. The researchers take into consideration that unimodal bilinguals (bilinguals of spoken language) produce "mixed" structures of language, which means they show elements of both languages in their speech. The children studied in this research are hearing with one or both parents being deaf, using sign language in the household and acquiring spoken language from their community. The researchers discovered that bimodal bilinguals produce what is known as code-blending. Code-blending is a term used in bimodal bilingual communication where signs in a sign language and words in a vocal language are produced at the same time. According to a Keynote article produced by Emmorey, Giezen & Gollan entitled Psycholinguistic, Cognitive, and Neural Implications of Bimodal Bilingualism, code blending in bimodal bilinguals is a very simple task, due to the fact that a spoken word can easily be accompanied by the corresponding sign.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5461974/

https://www.frontiersin.org/articles/10.3389/fpsyg.2014.01163/full

http://www.uibcongres.org/imgdb//archivo_dpo29150.pdf https://www.cambridge.org/core/journals/bilingualism-language-and-cognition/article/bimodal-bilingualism-language-and-cognition/489B8BBBFDE44EF491DE6E3EC3BCBB0B

 Neurological Effects of Bimodal Bilingualism- HANNAH 

There is evidence to suggest that Bimodal Bilingualism can alter the way that the brain processes either of its two languages separately. PET scans of a 37-year-old, right handed, bilingual (English and American Sign Language) male with left frontal lobe damage, resulting in no intellectual or visuospatial deficits, revealed evidence of increased right hemisphere activity compared to normal controls during spontaneous generation of narrative in both English and American Sign Language (ASL). Research with fMRI has found that showing sign language to deaf and hearing signers and showing written English to hearing non-signers activates the classical language areas of the left hemisphere in both cases. Studies in this area generally compare the behaviour or brain activity in normally hearing monolingual speakers of an oral language, genetically deaf, native signers, and normally hearing bimodal bilinguals. With the use of functional Near-Infrared Imaging (fNIR), Kovelman (2009) compared the performance and brain activity of these three groups in picture-naming tasks. These researchers found that, although performance in all groups was similar, neuroimaging revealed that bilinguals showed greater signal intensity within the posterior temporal regions (Wernicke's area) while using both languages in rapid alternation than when they were only using one language. While other bilinguals fluent in two spoken languages test higher than monolinguals in executive control tasks, the same cannot be said for bimodal bilinguals. Executive control tasks are complex mental processes required in achieving a goal--such as working memory and impulse control. Bilinguals must frequently switch between languages depending on who they are addressing and what environment they are in. This constant selection of a target language results in higher overall executive control. While speaking-only bilinguals must often switch fully between languages to not alarm those they are speaking with, bimodal bilinguals can often sign and speak simultaneously without any issue. As they are more free to integrate their two languages, bimodal individuals are not forced to consistently differentiate and therefore, have no increased level of executive control than monolinguals.

Working Memory & Visuospatial Cognition in the Bimodal Bilingual Brain - Hannah
PET studies have revealed a language modality-specific working memory neural region for sign language (which relies on a network of bilateral temporal, bilateral parietal, and left premotor activation), as well as a difference in activation of the right cerebellum in bimodal bilinguals between when they are signing or speaking. Similarities of activation have been found in Broca's area and semantic retrieval causes similar patterns of activation in the anterior left inferior frontal lobe. The bilateral parietal activation pattern for sign language is similar to neural activity during nonverbal visuospatial tasks. Bimodal individuals, like signing individuals, demonstrate elevated visuospatial processing when faced with mental rotation tasks than individuals with purely spoken language. This difference is due to the way in which signing individuals must rotate the language in their input 180 degrees before they can understand it. In signed language, the addressee is often facing the speaker and must first rotate the images they receive before they can be processed and turned into language. Therefore, bimodal bilinguals have a stronger relationship between linguistic and spatial processing in the brain. Even while communicating purely in spoken language, the right parietal cortex (responsible for processing visuospatial tasks) is activated.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2680472/

EDIT Face recognition- Emily
Sign language and oral language experience in bimodal bilinguals are shown to have separate effects on activation patterns within the superior temporal sulcus when recognizing facial expressions. The superior temporal sulcus, located in the temporal lobe of the brain, serves a variety of social processes. Some of these social processes include language perception or the ability to mimic the mental progressions of others (theory of mind). An fMRI study conducted by Deen B, Koldewyn K, Kanwisher N, Sax R concluded that the first cognitive function attributed to the superior temporal sulcus was language comprehension. Additionally, hearing signers (individuals who can hear and also speak sign language) do not show the strong left-lateralized activation for facial expression recognition that has been found within deaf signers. A potential reason for this is most facial processing studies done on humans show a stronger stimulation in the right hemisphere compared to the left. This indicates that both sign language experience and deafness can affect the neural organization for recognizing facial expressions.