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Aphasiology
Aphasiology is the study of language impairment usually resulting from brain damage, due to neurovascular accident—hemorrhage, stroke—or associated with a variety of neurodegenerative diseases, including different types of dementia. These specific language deficits, termed aphasias, may be defined as impairments of language production or comprehension that cannot be attributed to trivial causes such as deafness or oral paralysis. A number of aphasias have been described, but two are best known: expressive aphasia (Broca's aphasia) and receptive aphasia (Wernicke's or sensory aphasia). Acute aphasias Acute aphasias are often the result of tissue damage following a stroke. Expressive aphasia First described by the French neurologist Paul Broca in the nineteenth century, expressive aphasia causes the speech of those affected to display a considerable vocabulary but to show grammatical deficits. It is characterized by a halting speech consisting mainly of content words, i.e. ...
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Aphasia
Aphasia, also known as dysphasia, is an impairment in a person's ability to comprehend or formulate language because of dysfunction in specific brain regions. The major causes are stroke and head trauma; prevalence is hard to determine, but aphasia due to stroke is estimated to be 0.1–0.4% in developed countries. Aphasia can also be the result of brain tumors, epilepsy, autoimmune neurological diseases, brain infections, or neurodegenerative diseases (such as dementias). To be diagnosed with aphasia, a person's language must be significantly impaired in one or more of the four aspects of communication. In the case of progressive aphasia, a noticeable decline in language abilities over a short period of time is required. The four aspects of communication include spoken language production, spoken language comprehension, written language production, and written language comprehension. Impairments in any of these aspects can impact functional communication. The difficulties o ...
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Karl Wernicke
Carl (or Karl) Wernicke (; ; 15 May 1848 – 15 June 1905) was a German physician, anatomist, psychiatrist and neuropathologist. He is known for his influential research into the pathological effects of specific forms of encephalopathy and also the study of receptive aphasia, both of which are commonly associated with Wernicke's name and referred to as Wernicke encephalopathy and Wernicke's aphasia, respectively. His research, along with that of Paul Broca, led to groundbreaking realizations of the localization of brain function, specifically in speech. As such, Wernicke's area (a.k.a. Wernicke's Speech Area) has been named after the scientist. Biography Wernicke was born on May 15, 1848, in Tarnowitz, a small town in Upper Silesia, Prussia, now Tarnowskie Góry, Poland. He obtained his secondary education at the Königliche Gymnasium in Oppeln and the Maria-Magdalenen-Gymnasium in Breslau. Wernicke then studied medicine at the University of Breslau and did graduate w ...
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Agraphia
Agraphia is an acquired neurological disorder causing a loss in the ability to communicate through writing, either due to some form of motor dysfunction or an inability to spell. The loss of writing ability may present with other language or neurological disorders; disorders appearing commonly with agraphia are alexia, aphasia, dysarthria, agnosia, acalculia and apraxia. The study of individuals with agraphia may provide more information about the pathways involved in writing, both language related and motoric. Agraphia cannot be directly treated, but individuals can learn techniques to help regain and rehabilitate some of their previous writing abilities. These techniques differ depending on the type of agraphia. Agraphia can be broadly divided into central and peripheral categories. Central agraphias typically involve language areas of the brain, causing difficulty spelling or with spontaneous communication, and are often accompanied by other language disorders. Peripheral a ...
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Agrammatism
Agrammatism is a characteristic of non-fluent aphasia. Individuals with agrammatism present with speech that is characterized by containing mainly content words, with a lack of function words. For example, when asked to describe a picture of children playing in the park, the affected individual responds with, "trees..children..run." People with agrammatism may have telegraphic speech, a unique speech pattern with simplified formation of sentences (in which many or all function words are omitted), akin to that found in telegraph messages. Deficits in agrammaticism are often language-specific, however—in other words, "agrammaticism" in speakers of one language may present differently from in speakers of another. Errors made in agrammatism depend on the severity of aphasia. In severe forms language production is severely telegraphic and in more mild to moderate cases necessary elements for sentence construction are missing. Common errors include errors in tense, number, and ...
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Broca's Area
Broca's area, or the Broca area (, also , ), is a region in the frontal lobe of the dominant Cerebral hemisphere, hemisphere, usually the left, of the Human brain, brain with functions linked to speech production. Language processing in the brain, Language processing has been linked to Broca's area since Pierre Paul Broca reported impairments in two patients. They had lost the ability to speak after injury to the posterior inferior frontal gyrus (pars triangularis) (BA45) of the brain. Since then, the approximate region he identified has become known as Broca's area, and the deficit in language production as Broca's aphasia, also called expressive aphasia. Broca's area is now typically defined in terms of the pars opercularis and pars triangularis of the inferior frontal gyrus, represented in Korbinian Brodmann, Brodmann's Brodmann area, cytoarchitectonic map as Brodmann area 44 and Brodmann area 45 of the dominant hemisphere. Functional magnetic resonance imaging (fMRI) has show ...
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Language
Language is a structured system of communication that consists of grammar and vocabulary. It is the primary means by which humans convey meaning, both in spoken and signed language, signed forms, and may also be conveyed through writing system, writing. Human language is characterized by its cultural and historical diversity, with significant variations observed between cultures and across time. Human languages possess the properties of Productivity (linguistics), productivity and Displacement (linguistics), displacement, which enable the creation of an infinite number of sentences, and the ability to refer to objects, events, and ideas that are not immediately present in the discourse. The use of human language relies on social convention and is acquired through learning. Estimates of the number of human languages in the world vary between and . Precise estimates depend on an arbitrary distinction (dichotomy) established between languages and dialects. Natural languages are ...
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Anomic Aphasia
Anomic aphasia, also known as dysnomia, nominal aphasia, and amnesic aphasia, is a mild, fluent type of aphasia where individuals have word retrieval failures and cannot express the words they want to say (particularly nouns and verbs). By contrast, ''anomia'' is a deficit of expressive language, and a symptom of all forms of aphasia, but patients whose primary deficit is word retrieval are diagnosed with anomic aphasia. Individuals with aphasia who display anomia can often describe an object in detail and maybe even use hand gestures to demonstrate how the object is used, but cannot find the appropriate word to name the object. Patients with anomic aphasia have relatively preserved speech fluency, repetition, comprehension, and grammatical speech. Types * Word selection anomia is caused by damage to the posterior inferior temporal area. This type of anomia occurs when the patient knows how to use an object and can correctly select the target object from a group of objects ...
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Global Aphasia
Global aphasia is a severe form of nonfluent aphasia, caused by damage to the left side of the brain, that affects receptive and expressive language skills (needed for both written and oral language) as well as auditory and visual comprehension.Brookshire, R. H. (2007). Introduction to neurogenic communication disorders (Seventh edition.). St. Louis, Mo.: Mosby Elsevier. Acquired impairments of communicative abilities are present across all language modalities, impacting language production, comprehension, and repetition.Goodglass, H., and Kaplan, E. (1983). The assessment of aphasia and related disorders. Philadelphia: Lea and Febiger. Patients with global aphasia may be able to verbalize a few short utterances and use non-word neologisms,Manasco, H. M. (2014). Introduction to Neurogenic Communication Disorders. Burlington, MA: Jones & Barlett Learning. but their overall production ability is limited. Their ability to repeat words, utterances, or phrases is also affected. Due t ...
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Cerebral Cortex
The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. It is the largest site of Neuron, neural integration in the central nervous system, and plays a key role in attention, perception, awareness, thought, memory, language, and consciousness. The six-layered neocortex makes up approximately 90% of the Cortex (anatomy), cortex, with the allocortex making up the remainder. The cortex is divided into left and right parts by the longitudinal fissure, which separates the two cerebral hemispheres that are joined beneath the cortex by the corpus callosum and other commissural fibers. In most mammals, apart from small mammals that have small brains, the cerebral cortex is folded, providing a greater surface area in the confined volume of the neurocranium, cranium. Apart from minimising brain and cranial volume, gyrification, cortical folding is crucial for the Neural circuit, brain circuitry ...
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Wernicke's Area
Wernicke's area (; ), also called Wernicke's speech area, is one of the two parts of the cerebral cortex that are linked to speech, the other being Broca's area. It is involved in the comprehension of written and spoken language, in contrast to Broca's area, which is primarily involved in the production of language. It is traditionally thought to reside in Brodmann area 22, located in the superior temporal gyrus in the dominant cerebral hemisphere, which is the left hemisphere in about 95% of right-handed individuals and 70% of left-handed individuals. Damage caused to Wernicke's area results in receptive, fluent aphasia. This means that the person with aphasia will be able to fluently connect words, but the phrases will lack meaning. This is unlike non-fluent aphasia, in which the person will use meaningful words, but in a non-fluent, telegraphic manner. Emerging research on the developmental trajectory of Wernicke's area highlights its evolving role in language acquisiti ...
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Middle Cerebral Artery
The middle cerebral artery (MCA) is one of the three major paired cerebral artery, cerebral arteries that supply blood to the cerebrum. The MCA arises from the internal carotid artery and continues into the lateral sulcus where it then branches and projects to many parts of the lateral cerebral cortex. It also supplies blood to the anterior temporal lobes and the insular cortex, insular cortices. The left and right MCAs rise from trifurcations of the internal carotid artery, internal carotid arteries and thus are connected to the anterior cerebral artery, anterior cerebral arteries and the posterior communicating artery, posterior communicating arteries, which connect to the posterior cerebral artery, posterior cerebral arteries. The MCAs are not considered a part of the Circle of Willis. Structure The middle cerebral artery divides into four segments, named by the region they supply as opposed to order of branching as the latter can be somewhat variable: *M1: The ''sphenoidal' ...
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Superior Temporal Gyrus
The superior temporal gyrus (STG) is one of three (sometimes two) gyri in the temporal lobe of the human brain, which is located laterally to the head, situated somewhat above the external ear. The superior temporal gyrus is bounded by: * the lateral sulcus above; * the superior temporal sulcus (not always present or visible) below; * an imaginary line drawn from the preoccipital notch to the lateral sulcus posteriorly. The superior temporal gyrus contains several important structures of the brain, including: * Brodmann areas 41 and 42, marking the location of the auditory cortex, the cortical region responsible for the sensation of sound; * Wernicke's area, Brodmann area 22, an important region for the processing of speech so that it can be understood as language. The superior temporal gyrus contains the auditory cortex, which is responsible for processing sounds. Specific sound frequencies map precisely onto the auditory cortex. This auditory (or tonotopic) map is si ...
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