Instruct: Given a question, retrieve passages that can help answer the question.
Query: What is the number one cause of Broca's aphasia?
It is caused by acquired damage to the anterior regions of the brain, such as the left posterior inferior frontal gyrus or inferior frontal operculum, also described as Broca's area (Brodmann area 44 and Brodmann area 45).[6] It is one subset of a larger family of disorders known collectively as aphasia. Expressive aphasia contrasts with receptive aphasia, in which patients are able to speak in grammatical sentences that lack semantic significance, and generally also have trouble with comprehension.[3][7] Expressive aphasia differs from dysarthria, which is typified by a patient's inability to properly move the muscles of the tongue and mouth to produce speech. Expressive aphasia also differs from apraxia of speech which is a motor disorder characterized by an inability to create and sequence motor plans for speech.[8]
Shortly after Paul Broca published his findings on language deficits caused by damage to what is now referred to as Broca's area, Wernicke began pursuing his own research into the effects of brain disease on speech and language. Wernicke noticed that not all language deficits were the result of damage to Broca's area. Rather he found that damage to the left posterior, superior temporal gyrus resulted in deficits in language comprehension. This region is now referred to as Wernicke's area, and the associated syndrome is known as Wernicke’s aphasia (receptive aphasia), for his discovery.In 1897, with Theodor Ziehen (1862-1950), he founded the journal "Monatsschrift für Psychiatrie und Neurologie".
Examination of the brains of Broca's two historic patients with high-resolution MRI has produced several interesting findings. First, the MRI findings suggest that other areas besides Broca's area may also have contributed to the patients' reduced productive speech. This finding is significant because it has been found that, though lesions to Broca's area alone can possibly cause temporary speech disruption, they do not result in severe speech arrest. Therefore, there is a possibility that the aphasia denoted by Broca as an absence of productive speech also could have been influenced by the lesions in the other region. Another finding is that the region, which was once considered to be critical for speech by Broca, is not precisely the same region as what is now known as Broca's area. This study provides further evidence to support the claim that language and cognition are far more complicated than once thought and involve various networks of brain regions.[43]
Since studies carried out in the late 1970's[30] it has been understood that the relationship between Broca's area and Broca's aphasia is not as consistent as once thought.[31] Lesions to Broca's area alone don't result in a Broca's aphasia, nor do Broca's aphasic patients necessarily have lesions in Broca's area.[32] Lesions to Broca's area alone are known to produce just a transient mutism that resolves inside 3–6 weeks. This discovery suggests that Broca's area may be included in some aspect of verbalization or articulation; however, it does not address its part in sentence comprehension. Still, Broca's area frequently emerges in functional imaging studies of sentence processing.[33] However, it also becomes activated in word-level tasks.[34] This suggests that Broca’s area is not dedicated to sentence processing but supports a function common to both. In fact, Broca's area can show activation in such non-linguistic tasks as imagery of motion.[35]
In most cases, expressive aphasia is caused by a stroke in Broca's area or the surrounding vicinity. Broca's area is in the lower part of the premotor cortex in the language dominant hemisphere and is responsible for planning motor speech movements. However, cases of expressive aphasia have been seen in patients with strokes in other areas of the brain.[8] Patients with classic symptoms of expressive aphasia in general have more acute brain lesions, whereas patients with larger, widespread lesions exhibit a variety of symptoms that may be classified as global aphasia or left unclassified.[21]
One of the first indications of brain function lateralization resulted from the research of French physician Pierre Paul Broca, in 1861. His research involved the male patient nicknamed "Tan", who suffered a speech deficit (aphasia); "tan" was one of the few words he could articulate, hence his nickname. In Tan's autopsy, Broca determined he had a syphilitic lesion in the left cerebral hemisphere. This left frontal lobe brain area (Broca's area) is an important speech production region. The motor aspects of speech production deficits caused by damage to Broca's area are known as expressive aphasia. In clinical assessment of this aphasia, it is noted that the patient cannot clearly articulate the language being employed.
Damage and injury in the brain can severely lower one's ability to communicate, and therefore lower one's linguistic intelligence. Common forms of major damage are strokes, concussions, brain tumors, viral/bacterial damage, and drug-related damage. The three major linguistic disorders that result from these injuries are aphasia, alexia, and agraphia. Aphasia is the inability to speak, and can be caused by damage to Broca's area or the motor cortex. Alexia is the inability to read, which can arise from damage to Wernicke's area, among other places. Agraphia is the inability to write which can also arise from damage to Broca's area or the motor cortex. In addition, damage to large areas of the brain can result in any combinations of these disorders, as well as a loss of other abilities.
Broca's region Transcortical sensory aphasia Wernicke's aphasia
Broca’s aphasia, or non-fluent aphasia, is a language disorder caused by damage to Broca’s area and surrounding regions in the left frontal lobe. Those with non-fluent aphasia are able to understand language fairly well, but they struggle with language production and syntax. 
Mixed transcortical aphasia is the least common of the three transcortical aphasias (behind transcortical motor aphasia and transcortical sensory aphasia, respectively). This type of aphasia can also be referred to as "Isolation Aphasia". This type of aphasia is a result of damage that isolates the language areas (Broca’s, Wernicke’s, and the arcuate fasciculus) from other brain regions. Broca’s, Wernicke’s, and the arcuate fasiculus are left intact; however, they are isolated from other brain regions.
Broca's (expressive) aphasia is a type of non-fluent aphasia in which an individual’s speech is halting and effortful. Misarticulations or distortions of consonants and vowels, namely phonetic dissolution, are common. Individuals with expressive aphasia may only produce single words, or words in groups of two or three.[8] Long pauses between words are common and multi-syllabic words may be produced one syllable at a time with pauses between each syllable.[8] The prosody of a person with Broca's aphasia is compromised by shortened length of utterances and the presence of self-repairs and disfluencies.[9] Intonation and stress patterns are also deficient.[10]
Speech and language are mainly attributed to the parts of the cerebral cortex. Motor portions of language are attributed to Broca's area within the frontal lobe. Speech comprehension is attributed to Wernicke's area, at the temporal-parietal lobe junction. These two regions are interconnected by a large white matter tract, the arcuate fasciculus. Damage to the Broca's area results in expressive aphasia (non-fluent aphasia) while damage to Wernicke's area results in receptive aphasia (also called fluent aphasia).
Because Broca's area is anterior to the primary motor cortex which is responsible for movement of the face, hands, and arms, a lesion affecting Broca's areas may also result in hemiparesis (weakness of both limbs on the same side of the body) or hemiplegia (paralysis of both limbs on the same side of the body).[8] The brain is wired contralaterally, which means the limbs on right side of the body are controlled by the left hemisphere and vice versa.[15] Therefore, when Broca's area or surrounding areas in the left hemisphere are damaged, hemiplegia or hemiparesis often occurs on the right side of the body in individuals with Broca's aphasia.
Fast mapping in individuals with aphasia has gained research attention due to its effect on speaking, listening, reading, and writing. Research done by Blumstein makes an important distinction between those with Broca's aphasia, who are limited in physical speech, as compared to those with Wernicke's aphasia, who cannot link words with meaning. In Broca's aphasia, Blumstein found that whereas individuals with Wernicke's aphasia performed at the same level as the normal control group, those with Broca's aphasia showed slower reaction times for word presentations after reduced voice onset time stimuli. In short, when stimuli were acoustically altered, individuals with Broca's aphasia experienced difficulty recognizing the novel stimuli upon second presentation. Bloomstein's findings reinforce the crucial difference between one's ability to retain novel stimuli versus the ability to express novel stimuli. Because individuals with Wernicke's aphasia are only limited in their understanding of semantic meaning, it makes sense that the participant's novel stimulus recall would not be affected. On the other hand, those with Broca's aphasia lack the ability to produce speech, in effect hindering their ability to recall novel stimuli. Although individuals with Broca's aphasia are limited in their speech production, it is not clear whether they simply cannot formulate the physical speech or if they actually did not process the stimuli.
When evaluating the prognosis of a patient, the main contributing participant factors that influence the extent of neuroplasticity, or the brain's ability to change are: age, lesion location, pre-existing cognitive status, motivation, age, overall health, and interaction amongst these. After brain damage, initial signs of global aphasia may appear within the first two days due to brain swelling (cerebral edema). With some time and natural recovery, impairment presentation may progress into expressive aphasia (most commonly) or receptive aphasia. Due to the size and location of the lesion associated with global aphasia, the prognosis for language abilities is poor. Research has shown that the prognosis of long-term language abilities is determined by the initial severity level of aphasia within the first four weeks after a stroke. As a result, there is a poor prognosis for persons who retain a diagnosis of aphasia after one month due to limited initial language abilities. Nonetheless, in the first year post-stroke, patients with global aphasia showed improvement in their Western Aphasia Battery (WAB) scores from baseline. When compared to individuals with Broca’s, Wernicke’s, anomic, and conduction types of aphasia, those with Broca’s aphasia showed the best rate and extent of improvement followed by global aphasia. The rate of improvement in language function was highest in the first four weeks after stroke.
It is important to note that there are typical difficulties with speech and language that come with normal aging as well. As we age language can become more difficult to process resulting in a slowing of verbal comprehension, reading abilities and more likely word finding difficulties. With each of these though, unlike some aphasias, functionality within daily life remains intact.Localizationist approaches aim to classify the aphasias according to their major presenting characteristics and the regions of the brain that most probably gave rise to them. Inspired by the early work of nineteenth-century neurologists Paul Broca and Carl Wernicke, these approaches identify two major subtypes of aphasia and several more minor subtypes:Recent classification schemes adopting this approach, such as the "Boston-Neoclassical Model", also group these classical aphasia subtypes into two larger classes: the nonfluent aphasias (which encompasses Broca's aphasia and transcortical motor aphasia) and the fluent aphasias (which encompasses Wernicke's aphasia, conduction aphasia and transcortical sensory aphasia). These schemes also identify several further aphasia subtypes, including: anomic aphasia, which is characterized by a selective difficulty finding the names for things; and global aphasia, where both expression and comprehension of speech are severely compromised.
Patients with damage to Broca's area and/or to neighboring regions of the left inferior frontal lobe are often categorized clinically as having Expressive aphasia (also known as Broca's aphasia). This type of aphasia, which often involves impairments in speech output, can be contrasted with Receptive aphasia, (also known as Wernicke's aphasia), named for Karl Wernicke, which is characterized by damage to more posterior regions of the left temporal lobe, and is often characterized by impairments in language comprehension.
Transcortical sensory aphasia is caused by lesions in the inferior left temporal lobe of the brain located near Wernicke's area, and is usually due to minor hemorrhage or contusion in the temporal lobe, or infarcts of the left posterior cerebral artery (PCA). One function of the arcuate fasciculus is the connection between Wernicke’s and Broca’s area. In TSA Wernicke’s and Broca’s areas are spared, meaning that lesions do not occur in these regions of the brain. However, since the arcuate fasciculus, Wernicke's area, and Broca's area are secluded from the rest of the brain in TSA, patients still have intact repetition (as information from the arcuate fasciculus is relayed to Broca’s area), but cannot attach meaning to words, either spoken or heard.
Language processing has been linked to Broca's area since Pierre Paul Broca reported impairments in two patients.[2] They had lost the ability to speak after injury to the posterior inferior frontal gyrus (pars triangularis) (BA45) of the brain.[3] 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 Brodmann's cytoarchitectonic map as Brodmann area 44 and Brodmann area 45 of the dominant hemisphere.[3]
Anomic aphasia is the inability to recall words and names and is a common symptom of patients with Aphasia and Alzheimer's disease (AD). Research has been conducted to find out how these particular diseases affect TOTs in these individuals. In a study by Beeson, Holland, and Murray (1997), participants with Alzheimer's disease and three classic aphasic syndromes (Broca’s, anomic, and conduction aphasia) were instructed to name famous people. Those with anomic aphasia showed to be superior to the other groups in their ability to naming famous people that were presented. This finding was expected as the group has relatively mild aphasia. However, the Broca’s conduction and AD groups did not differ in immediate or delayed naming of famous faces. All of the groups provided some basic identifying semantic information for at least half of the items presented, suggesting a fair number of items potentially in TOT. Conduction and Broca’s groups showed strongest evidence of TOT, performing better than the other groups in identification of initial letters.
In the classical sense, expressive aphasia is the result of injury to Broca's area; it is often the case that lesions in specific brain areas cause specific, dissociable symptoms,[28] although case studies show there is not always a one-to-one mapping between lesion location and aphasic symptoms.[25] The correlation between damage to certain specific brain areas (usually in the left hemisphere) and the development of specific types of aphasia makes it possible to deduce (albeit very roughly) the location of a suspected brain lesion based only on the presence (and severity) of a certain type of aphasia, though this is complicated by the possibility that a patient may have damage to a number of brain areas and may exhibit symptoms of more than one type of aphasia. The examination of lesion data in order to deduce which brain areas are essential in the normal functioning of certain aspects of cognition is called the deficit-lesion method; this method is especially important in the branch of neuroscience known as aphasiology. Cognitive science - to be specific, cognitive neuropsychology - are branches of neuroscience that also make extensive use of the deficit-lesion method.[29]
Although localizationist approaches provide a useful way of classifying the different patterns of language difficulty into broad groups, one problem is that a sizeable number of individuals do not fit neatly into one category or another. Another problem is that the categories, particularly the major ones such as Broca's and Wernicke's aphasia, still remain quite broad. Consequently, even amongst individuals who meet the criteria for classification into a subtype, there can be enormous variability in the types of difficulties they experience.
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 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 the specific non-fluent aphasia.
Wernicke's area ( or ; ), also called Wernicke's speech area, is one of the two parts of the cerebral cortex that are linked to speech (the other is Broca's area). It is involved in the comprehension of written and spoken language (in contrast to Broca's area that is involved in the production of language). It is traditionally thought to be in Brodmann area 22, which is located in the superior temporal lobe in the dominant cerebral hemisphere (which is the left hemisphere in about 95% of right handed individuals and 60% 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.
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. It is also the name of a scientific journal covering the area. 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).