Aphasia: An Acquired Language Condition from a Neurolinguistic Perspective

Aphasia, from neurolinguistics perspective, is an acquired language condition where the left hemisphere of a person’s brain is damaged. This disorder was characterized by the inability to understand spoken and written language as compared to the speaker’s anticipation. It was observed that the typical type of aphasia is a cerebral vascular accident, also referred to as a stroke, which can be caused by methods such as repeated stress on a particular part of the brain as a result of traumatic accident or gunshot wounds (Edwards, 2016). Over the years, this has become subject to research seeking to achieve a complete understanding of the relationship between language and the brain.

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In their study of their phrenology, Gall, Sperzheim, and others, claimed that the activities of a particular portion of the brain and the size of the brain area affected the degree of development of the human brain. The assertion that these phrenologists also believed was that the size of the skull could be used to determine the capacity of an individual since the size of portions was proportional to the brain size. They also argued that the moral, intellectual, and spiritual ability of an individual depended on these aspects.

Broca, in his theory of brain function, somehow agreed with the previous phrenological studies that language is located at the frontal lobes in the human brain, particularly above the eye sockets unlike many other claims that had been refuted by 1861. Paul Broca considered Leourbogne a subject of research since he did not show any sign of motor or tongue impairment characterized by his ability to understand languages but not being able to speak except for the syllable “tan”, which made him known as Tan.

Tan further developed complications that led to paralysis caused by infection and soon after that died from generalized sepsis, therefore, attracting Broca’s attention. By examining Tan, Broca was able to determine the position of language in the human brain, which led to an agreement with Aubertin and Bouillaud's arguments. The autopsy of Tan’s left temporal lobe of the brain revealed a lesion which he supposed to be the source of his speech and language deficit issue. He further studied the brain and realized that it was softer than the healthy brain and the more he moved posteriorly, the typical the consistency of the brain tissues.

After the autopsy, Broca began his analysis of the findings of clinical anatomical correlation, which was a traditional method. Borca divided Tan’s illness into three parts. In the first stage, he deduced that the lesion caused an isolated deficit in language, the second stage causing partial paralysis of the face and right arm whereas in the last stage the lesion appeared to have greatly spread which caused paralysis on the left leg. The stages laid a foundation of his study on language abnormality about the factors that caused it, in the brain. From the observations he made, Borca found that Lebourgne, his patient, did not show the deficiency of non-linguistic communication as well as receptive communication as evidenced by his ability to understand and respond to speech. He concluded that Lebourgne had a problem which he termed as” faculty of articulate language” since its abolished speech and not his intelligence (Green, 330).

Before Broca's theory, other phrenological scientists’ thought that the relative distances between anatomical landmarks of the human brain and skull determined the higher-order functions localization. Paul Borca disagreed with the theory and deduced that the size of lobes in the human brain and skull was relatively consistent from one individual to another, therefore arguing that higher-order functions were determined by localization of convolutions rather than the distance between them. He also suggested that the relative positioning of the convolutions was caused by apertures, among other landmarks hence the varying sizes of brains. From these findings, Borca concluded that his patient’s condition of unspoken language resulting from lesions on the foot of frontal convolution.

In his study of language and brain, Carl Wernicke classified aphasic syndromes which led him to a discovery that there are two distinct classifications of these syndromes each of which led to lesions in the brain and that these areas have varying tasks about language representation and processing (Green, 332). In his paper, Wernicke highlighted nine causes of language disorders as a result of acquired disease of the brain. He examined two patients and realized that both manifested deficit in understanding and one thought to be deaf. Unlike Broca's finding of depicting a patient to be partially mute, Wernicke found that his patients would recognize gestures and patterns. He found out that errors in language and speech were, as a result, of omission and choice of sounds evidenced by his patients’ ability to speak fluently but not being able to make sense.

Wernicke predicted that his patient's related sounds by rhyme or semantic relationships since he (Wernicke) together with other scientists did not understand words which were thought to be non-existing in the German language therefore their speech did not convey any information (Shalom, 121). The death of one of his patients caused him to perform further study from the autopsy of the brain. He predicted that the deficit of expressive language was due to the same lesion causing a reduction in language processing capability and not as argued by Broca although he agreed with findings that the location of defective tissues was the left hemisphere of the brain. Wernicke also described the primary auditory cortex to be responsible for speech recognition which he argued that it is responsible for modification of sensory and motor information.

In his model, Wernicke adopted the notion that various components of the brain are connected. He added that psycholinguistic elements were considered to constitute psychological entities that were legitimately represented as the center of brain functions. He further proposed that, concerning the posterior language area, simple psychological functions were seen to be located in the first temporal gyrus (Capasso, 217). This approach immediately received appreciation, which became the method that was adopted by scientists as the dominant method of classifying aphasia.

Conclusion

In conclusion, loss of speech occurred as a result of lesions in the anterior part of the brain before any paralysis or intellectual ability. These lobes were considered to be where the articulated language sits. The atomic descriptions made by Broca are not enough to conclude; however, tests on various patients depicted a psychological understanding of how speech and language is output rather than processed in the human brain. It was also stipulated that human intelligence could not be measured using language impairment. In Tan’s case, he was able to understand and convey information effectively despite his inability to speak, causing more confusion on the subject.

Works Cited

Green. Classics in the History of Psychology. York University, Toronto, Ontario. 2000. Print

Shalom, Poeppel. Functional anatomic models of language: assembling the pieces. Neuroscientist, 14, 119–127.

Bose, Lieshout. Effects of utterance length on lip kinematics in aphasia. Brain and Language 106, 4–14.

Hickok, Costanzo, Capasso, Miceli. The role of Broca’s area in speech perception: Evidence from aphasia revisited. Brain and Language, 119.(2011) 214–220.