| FazBrowse Wikipedia Viewer | Main Page | | |
| Viewing: https://en.wikipedia.org/wiki/Lateralization_of_brain_function |
| Contents |
|---|
| Misconceptions |
| Popular psychology |
| Additional images |
| External links |
| Bibliography |
Broca's aphasia is a specific type of expressive aphasia and is so named due to the aphasia that results from damage or lesions to the Broca's area of the brain, that exists most commonly in the left inferior frontal hemisphere. Thus, the aphasia that develops from the lack of functioning of the Broca's area is an expressive and non-fluent aphasia. It is called 'non-fluent' due to the issues that arise because Broca's area is critical for language pronunciation and production. The area controls some motor aspects of speech production and articulation of thoughts to words and as such lesions to the area result in specific non-fluent aphasia.
Wernicke's aphasiaeditWernicke's aphasia is the result of damage to the area of the brain that is commonly in the left hemisphere above the Sylvian fissure. Damage to this area causes primarily a deficit in language comprehension.While the ability to speak fluently with normal melodic intonation is spared, the language produced by a person with Wernicke's aphasia is riddled with semantic errors and may sound nonsensical to the listener.Wernicke's aphasia is characterized by phonemic paraphasias, neologism or jargon.Another characteristic of a person with Wernicke's aphasia is that they are unconcerned by the mistakes that they are making.
An illustration of the oversimplified model of hemisphericity
The concept of "right-brained" or "left-brained" individuals is considered a widespread myth which oversimplifies the true nature of the brain's cerebral hemispheres. According to this view, traits associated with intuition and creativity are located in the right side of the brain, while traits associated with rationality are located in the left hemisphere. Although certain functions show a degree of lateralization in the brain—with language predominantly processed in the left hemisphere, and spatial and nonverbal reasoning in the right—these functions are not exclusively tied to one hemisphere. A study from the University of Utah in 2013 found that brain scans revealed similarity on both sides of the brain, personality and environmental factors aside.
Terence Hines states that the research on brain lateralization is valid as a research program, though commercial promoters have applied it to promote subjects and products far outside the implications of the research. For example, the implications of the research have no bearing on psychological interventions such as eye movement desensitization and reprocessing (EMDR) and neurolinguistic programming, brain-training equipment, or management training.
Research by Michael Gazzaniga and Roger Wolcott Sperry in the 1960s on split-brain patients led to an even greater understanding of functional laterality. Split-brain patients are patients who have undergone corpus callosotomy (usually as a treatment for severe epilepsy), a severing of a large part of the corpus callosum. The corpus callosum connects the two hemispheres of the brain and allows them to communicate. When these connections are cut, the two halves of the brain have a reduced capacity to communicate with each other. This led to many interesting behavioral phenomena that allowed Gazzaniga and Sperry to study the contributions of each hemisphere to various cognitive and perceptual processes. One of their main findings was that the right hemisphere was capable of rudimentary language processing, but often has no lexical or grammatical abilities. Eran Zaidel also studied such patients and found some evidence for the right hemisphere having at least some syntactic ability.
Language is primarily localized in the left hemisphere. While the left hemisphere has proven to be more optimized for language, the right hemisphere has the capacity with emotions, such as sarcasm, that can express prosody in sentences when speaking. According to Sheppard and Hillis, "The right hemisphere is critical for perceiving sarcasm (Davis et al., 2016), integrating context required for understanding metaphor, inference, and humour, as well as recognizing and expressing affective or emotional prosody—changes in pitch, rhythm, rate, and loudness that convey emotions". One of the experiments carried out by Gazzaniga involved a split-brain male patient sitting in front of a computer screen while having words and images presented on either side of the screen, and the visual stimuli would go to either the right or left visual field, and thus the left or right brain, respectively. It was observed that if the patient was presented with an image to his left visual field (right brain), he would report not seeing anything. If he was able to feel around for certain objects, he could accurately pick out the correct object, despite not having the ability to verbalize what he saw.
| View original on Wikipedia | Back | FazBrowse Home |