Biological Basis for Language and Evidences for Modularity of the Brain

Impairments or anomalies found during the processing or production of linguistic information are called language disorders. There are mainly two types of language disorders namely, acquired language disorder and developmental language disorder. Language disorders are mainly concerned with the comprehension of speech and its articulation. Some common symptoms of language disorders are delayed language development, not achieving adult-like fluency and so on. Language disorders include aphasia.

Acquired aphasia is the impairment to language resulting from brain damage. Both Broca and Wernicke found patients with language impairments after receiving some form of injury on the left side of their brains. The difference is that Broca’s patient could only produce one syllable “tan” implying that there is a part in the brain which is responsible for speech production. Meanwhile, Wernicke had a couple of patients who spoke nonsensical words fluently after receiving injury on a different part of the left hemisphere implying that there is another area within the left hemisphere responsible for speech comprehension.  This kind of influence on language is further confirmed by transcortical aphasia where injury within specific areas of the brain affect language differently. From these results, we can assume that the left hemisphere is comparatively more responsible for language acquisition. That is, the brain shows modularity.

Modularity of the brain should be confirmed with double dissociation. If two cognitive abilities can be shown to be impaired independently of each other, then this could be evidence for their independence, that is, the brain shows modularity. Specific Language Impairment clearly affects language resulting in delay and plateau for language acquisition despite having and IQ level of 85+ whereas, William’s Syndrome, a cognitive disorder, does not hamper achieving an adult-like proficiency despite having an IQ level of 40+. This clearly depicts that there is a fine difference between general cognitive disorders and language disorders, confirming modularity of the brain.

Despite being a genetic disorder, SLI and WS affected language separately. SLI impaired language acquisition severely whereas; WS barely damaged acquiring linguistic knowledge. The genetic disorders selectively hampered language learning as well as selectively spared language learning. This distinction of genes gives evidence for the biological basis of language. This is how the shared symptoms of the language disorders are significant.