I came across an interesting review article titled Dissociating Language and Word Meaning in the Bilingual Brain by Michael W.L. Chee. The study was conducted by Crinion and colleagues, and gives a neuroscience perspective of dissociating brain regions sensitive only to word meaning from those sensitive to the combination of meaning and language. I found this article interesting because I agree with the statement presented in the article of how “there seems to be an ease with which bilingual persons can communicate in different languages with relatively little confusion.” Also, we have recently discussed in class how a deaf signer can also read English and I became interested in how the brain processed this. Though instead, I found an equally interesting article describing this process for bilingual speakers.
There have been functional imaging studies on bilingualism that have evaluated how different languages are represented in the brain by looking at both the single-word and sentence levels. However, it appears that much less work has addressed the question of how a bilingual can keep languages apart during reading and language production. In the studied that was reviewed, it was demonstrated that there are language dependent neuronal responses while single words are processed for meaning.
This study examined German and English, and Japanese and English bilingual participants. The participants had to make a semantic decision regarding the second word of visually presented prime-target pairs of two written names (of objects or animals, or one of each). There was a 250ms time interval between the onset of seeing the prime and target word. Each target word was associated with one of three possible verification questions that focused primarily on the perceptual properties of the object or animal. For example, they had to make a decision relating to leg length (long or short legs), coloration, and open or closed handles (spoon vs. teacup). This design not only manipulated the language of the target word, but also whether the prime and target were semantically related or unrelated, and whether they were written in the same or different languages. This led to the following conditions for each target language: 1. Same language with an unrelated meaning 2. Same language with a semantically related meaning 3. Different language with an unrelated meaning 4. Different language with a semantically related meaning 5. Different language with the same meaning.
In the left caudate, it was found that there was greater activation for unrelated-semantically related primes in the same language. However, when there was a different language presented activation was greater than semantic priming within languages. This was consistent with Crinion’s proposal that caudate responses increase when there is a change in semantics or a change in language. From these findings, it had been suggested that the left caudate plays a universal role in monitoring and controlling the language that is in use at any given time. This study is important because previous functional imaging experiments could not answer this question, and Crinion et al replicated these results over three different experiments.