Paraphasia

Last updated October 14, 2024

Paraphasia is a type of language output error commonly associated with aphasia and characterized by the production of unintended syllables, words, or phrases during the effort to speak. Paraphasic errors are most common in patients with fluent forms of aphasia, and come in three forms: phonemic or literal, neologistic, and verbal.^[1] Paraphasias can affect metrical information, segmental information, number of syllables, or both. Some paraphasias preserve the meter without segmentation, and some do the opposite. However, most paraphasias affect both partially.^[2]

Causes

Paraphasia is associated with fluent aphasias, characterized by "fluent spontaneous speech, long grammatically shaped sentences and preserved prosody abilities."^[4] Examples of these fluent aphasias include receptive or Wernicke's aphasia, anomic aphasia, conduction aphasia, and transcortical sensory aphasia, among others. All of these lead to a difference in processing efficiency, which is often caused by damage to a cortical region in the brain (in receptive aphasia, for example, the lesion is in or near Wernicke's area); lesion location is the most important determining factor for all aphasic disorders, including paraphasia – the location of the lesion can be used to hypothesize the type of aphasic symptoms the patient will display.^[5] This lesion can be caused by a variety of different methods: malfunctioning blood vessels (caused, for example, by a stroke) in the brain are the cause of 80% of aphasias in adults, as compared to head injuries, dementia and degenerative diseases, poisoning, metabolic disorders, infectious diseases, and demyelinating diseases.^[4] Lesions involving the posterior superior temporal lobe are often associated with fluent aphasias.^[6]

Damage to the brain's language centers

Two areas of the brain, Broca's area and Wernicke's area, are responsible for various disruptions in speech when damaged. Each is defined by their distinct characteristics. Broca's aphasia is characterized by non-fluent or telegraphic-type speech - where articles, conjunctions, prepositions, auxiliary verbs, pronouns and morphological inflections (plurals, past tense) are omitted.^[7] The word substitutions are infrequent and distortion of consonants and simplification of consonant clusters is frequent. Content words such as nouns, verbs and adjectives may be preserved. Subjects of this aphasia are aware of their errors in speech. Damage to the Broca's area does not affect comprehension of speech.^[8]

Wernicke's aphasia is characterized by fluent language with made up or unnecessary words with little or no meaning to speech. Those who suffer from this type of aphasia have difficulty understanding others' speech and are unaware of their own mistakes. When corrected they will repeat their verbal paraphasias and have trouble finding the correct word. Wernicke's area is found in the dominant hemisphere of the posterior gyrus of the first temporal convolution of the brain, whereas Broca's area is found anterior to the Wernicke's area.^[9]

Symptoms

Phonemic paraphasia

Phonemic paraphasia, also referred to as phonological paraphasia or literal paraphasia, refers to the substitution of a word with a nonword that preserves at least half of the segments and/or number of syllables of the intended word. This can lead to a variety of errors, including formal ones, in which one word is replaced with another phonologically related to the intended word; phonemic ones, in which one word is replaced with a nonword phonologically related to the intended word; and approximations, an attempt to find the word without producing either a word or nonword.^[2]^[10] These types of errors are associated with Wernicke's aphasia, among others.^[1]^[4] Phonemic paraphasias are often caused by lesions to the external capsule, extending to the posterior part of the temporal lobe or internal capsule.^[5] This type of paraphasia also occurs in other languages as well. For example, case studies have been performed with German speakers, which demonstrated that 30.8% of paraphasias occurred at the beginning of the word in patients with Wernicke's aphasia and 22.6% for patients with Broca's aphasia. In English speakers this tendency to create errors at the beginning of the word remained.^[10]

Types of phonemic paraphasias^[11]^[12]
- Anticipatory errors occur when a syllable from later in the word replaces a syllable from earlier in the word – "papple" for apple or "lelephone" for telephone.
- Perseverative errors occur when a syllable from earlier in the word replaces a syllable from later in the word – for example, "gingerjed" for gingerbread.
- Paradigmatic errors based on similarity in how the sounds are formed can also occur – "marmer" for barber, i.e.
- Addition errors, in which a segment is added that bears no relation to the intended word, are much rarer than anticipatory, perseverative, or paradigmatic errors, though they do occur. Most often what can be mistaken for an addition error is an anticipatory error from the words surrounding the intended one. However, an example of a possible addition error could be "selezant" for elephant.
- Substitution errors involve a clear phonological substitution, such as "ragon" for wagon.
- Epenthetic errors are the insertion of a segment into the target, as in the case of "plants" for pants.
- Finally, metathetical errors are the full exchange of segments like "deks" for desk.

Neologistic paraphasia

Neologistic paraphasias, a substitution with a non-English or gibberish word, follow pauses indicating word-finding difficulty.^[13] They can affect any part of speech, and the previously mentioned pause can be used to indicate the relative severity of the neologism; less severe neologistic paraphasias can be recognized as a distortion of a real word, and more severe ones cannot. The hypothesized source for these neologisms is “a device which quasirandomly combines English phonemes in a phonotactically regular way.”^[14] A neologistic paraphasia can be thought of as a neologism resulting from aphasia, rather than any other of the sources with which they are associated. Neologistic paraphasia is often associated with receptive aphasia and jargon aphasia.^[4]^[14]

Types of Neologistic paraphasias
- There are also various types of neologistic paraphasias. They can be phonologically related to a prior word, a following word, the intended word, or another neologism. The neologistic paraphasia shares phonemes or the position of phonemes with the related word. This most often occurs when the word and neologistic paraphasia are in the same clause.^[14] Neologistic paraphasias have a less stringent relationship with the target word than phonological paraphasias – where a phonological paraphasia has more than half of the target word’s phonemes, a neologistic paraphasia has less than half.^[12]

Verbal paraphasia

Verbal paraphasias are confusions of words or the replacement of one word by another real word; another definition is that of a contextually inappropriate English word or an English word of a syntactically incorrect class – the wrong part of speech, for example.^[14] Verbal paraphasias do not often preserve length, although the gender of the target word was preserved in more than half of the errors in one case study. It is hypothesized that verbal paraphasias are not the result of a random process but from a precise deficit in a single area.^[15] Verbal paraphasias are the only type of paraphasias that can also be linked to nonfluent aphasias, and they are mainly caused by lesions to the posterior temporal region of the brain, the head of the caudate nucleus, or both.^[16]

Examples
- These errors can be semantic, in which the meaning of the word is related to that of the intended word (car for van, for example).^[16] Semantic paraphasias can be further subdivided into six different types.^[12]
  - Coordinate semantic paraphasias replace the target word with one that is from the same category, such as tiger for lion.
  - Associate semantic paraphasias replace the target word with one that is related to the target but is not of the same category, like replacing foot with shoe.
  - Superordinate semantic paraphasias replace a specific target word with a more generalized group to which the target word involves, such as replacing pear with fruit.
  - Subordinate semantic paraphasias are the opposite of superordinate semantic paraphasias and replace the target word with one that is more specific – rose, for flower, for example.
  - Part-whole semantic paraphasias replace the "whole" with the "part" as in finger for hand; or, conversely, the part with the whole, in the case of leg for foot.
  - Finally, a visual semantic paraphasia replaces the target word with a word that shares visual features with the target, such as knife for nail.
- Random errors, in which the word has no relation to the target, also occur.

Perseverative paraphasia

Perseverative paraphasia is a type of paraphasia in which the previous response persists and interferes with retrieval of new responses. (See the experimental case study D.L.A published by Dennis in 1976.) It is associated with lesions in the left caudate nucleus.^[5]

Treatment

Many language impairments, including paraphasic errors, are reduced in number through spontaneous recovery of neurological function; this occurs most often with stroke patients within the first three months of recovery. Lesions associated with ischemic strokes have a shorter spontaneous recovery time, within the first two weeks; on the other hand, lesions associated with hemorrhagic strokes have a longer period for spontaneous recovery, from four to eight weeks. Whether spontaneous recovery occurs or not, treatment must begin immediately after the stroke, with support from a speech therapist or speech pathologist. A traditional approach requires treatment beginning at the level of breakdown – in the case of paraphasia, at the level of the phoneme. There are commercially available workbooks that provide various activities such as letter, word-picture, or word-word matching, and sentence completion, among other things. The difficulty of these activities varies with the level of treatment. However, these treatments have not been proven to be clinically productive.^[4]

A 1988 study by Mary Boyle proposed a method focused on oral reading to treat phonemic paraphasias, which was partially successful, resulting in fewer phonemic paraphasias but a slower rate of speech. Treatments lasted for 50 minutes and occurred once a week. During these treatment sessions, the patient was instructed to look at twenty different phrases, each consisting of one to three syllables, then read the phrase. If the patient failed to read the phrase, the process was repeated. If the patient failed to read the phrase again, the process was abandoned. To progress from a set of one syllable phrases to two syllable phrases and two syllable phrases to three syllable phrases, an 80% success rate was necessary. This treatment was partially successful. Although fewer phonemic paraphasias were produced due to this treatment, speaking efficiency was not improved by this study. This is partially because the focus of the treatment was on sound production rather than semantic content. Improvements lasted for six weeks before the patient regressed.^[17]

Experimental (magnetic-stimulation-induced) paraphasias

Transient paraphasias (as well as other language defects such as speech arrest) can be generated by artificially activating the brain's language network with Transcranial magnetic stimulation (TMS). With navigated TMS (nTMS), nodes of the language network can be located presurgically so that critical areas can be saved when performing tumor or epilepsy surgery.^[18]

Related Research Articles

<span class="mw-page-title-main">Aphasia</span> Inability to comprehend or formulate language

In aphasia, a person may be unable to comprehend or unable to formulate language because of damage to 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 the Global North. Aphasia can also be the result of brain tumors, epilepsy, autoimmune neurological diseases, brain infections, or neurodegenerative diseases.

Expressive aphasia is a type of aphasia characterized by partial loss of the ability to produce language, although comprehension generally remains intact. A person with expressive aphasia will exhibit effortful speech. Speech generally includes important content words but leaves out function words that have more grammatical significance than physical meaning, such as prepositions and articles. This is known as "telegraphic speech". The person's intended message may still be understood, but their sentence will not be grammatically correct. In very severe forms of expressive aphasia, a person may only speak using single word utterances. Typically, comprehension is mildly to moderately impaired in expressive aphasia due to difficulty understanding complex grammar.

In neuroscience and psychology, the term language center refers collectively to the areas of the brain which serve a particular function for speech processing and production. Language is a core system that gives humans the capacity to solve difficult problems and provides them with a unique type of social interaction. Language allows individuals to attribute symbols to specific concepts, and utilize them through sentences and phrases that follow proper grammatical rules. Finally, speech is the mechanism by which language is orally expressed.

Wernicke's aphasia, also known as receptive aphasia, sensory aphasia, fluent aphasia, or posterior aphasia, is a type of aphasia in which individuals have difficulty understanding written and spoken language. Patients with Wernicke's aphasia demonstrate fluent speech, which is characterized by typical speech rate, intact syntactic abilities and effortless speech output. Writing often reflects speech in that it tends to lack content or meaning. In most cases, motor deficits do not occur in individuals with Wernicke's aphasia. Therefore, they may produce a large amount of speech without much meaning. Individuals with Wernicke's aphasia often suffer of anosognosia – they are unaware of their errors in speech and do not realize their speech may lack meaning. They typically remain unaware of even their most profound language deficits.

Broca's area, or the Broca area, is a region in the frontal lobe of the dominant hemisphere, usually the left, of the brain with functions linked to speech production.

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 and receptive aphasia.

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.

Anomic aphasia is a mild, fluent type of aphasia where individuals have word retrieval failures and cannot express the words they want to say. 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.

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, which is 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.

In neurology, conduction aphasia, also called associative aphasia, is an uncommon form of difficulty in speaking (aphasia). It is caused by damage to the parietal lobe of the brain. An acquired language disorder, it is characterised by intact auditory comprehension, coherent speech production, but poor speech repetition. Affected people are fully capable of understanding what they are hearing, but fail to encode phonological information for production. This deficit is load-sensitive as the person shows significant difficulty repeating phrases, particularly as the phrases increase in length and complexity and as they stumble over words they are attempting to pronounce. People have frequent errors during spontaneous speech, such as substituting or transposing sounds. They are also aware of their errors and will show significant difficulty correcting them.

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 as well as auditory and visual comprehension. Acquired impairments of communicative abilities are present across all language modalities, impacting language production, comprehension, and repetition. Patients with global aphasia may be able to verbalize a few short utterances and use non-word neologisms, but their overall production ability is limited. Their ability to repeat words, utterances, or phrases is also affected. Due to the preservation of the right hemisphere, an individual with global aphasia may still be able to express themselves through facial expressions, gestures, and intonation. This type of aphasia often results from a large lesion of the left perisylvian cortex. The lesion is caused by an occlusion of the left middle cerebral artery and is associated with damage to Broca's area, Wernicke's area, and insular regions which are associated with aspects of language.

Transcortical sensory aphasia (TSA) is a kind of aphasia that involves damage to specific areas of the temporal lobe of the brain, resulting in symptoms such as poor auditory comprehension, relatively intact repetition, and fluent speech with semantic paraphasias present. TSA is a fluent aphasia similar to Wernicke's aphasia, with the exception of a strong ability to repeat words and phrases. The person may repeat questions rather than answer them ("echolalia").

Transcortical motor aphasia (TMoA), also known as commissural dysphasia or white matter dysphasia, results from damage in the anterior superior frontal lobe of the language-dominant hemisphere. This damage is typically due to cerebrovascular accident (CVA). TMoA is generally characterized by reduced speech output, which is a result of dysfunction of the affected region of the brain. The left hemisphere is usually responsible for performing language functions, although left-handed individuals have been shown to perform language functions using either their left or right hemisphere depending on the individual. The anterior frontal lobes of the language-dominant hemisphere are essential for initiating and maintaining speech. Because of this, individuals with TMoA often present with difficulty in speech maintenance and initiation.

Mixed transcortical aphasia is the least common of the three transcortical aphasias. 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 from other brain regions. Broca's, Wernicke's, and the arcuate fasiculus are left intact; however, they are isolated from other brain regions.

The lateralization of brain function is the tendency for some neural functions or cognitive processes to be specialized to one side of the brain or the other. The median longitudinal fissure separates the human brain into two distinct cerebral hemispheres, connected by the corpus callosum. Although the macrostructure of the two hemispheres appears to be almost identical, different composition of neuronal networks allows for specialized function that is different in each hemisphere.

Paragrammatism is the confused or incomplete use of grammatical structures, found in certain forms of speech disturbance. Paragrammatism is the inability to form grammatically correct sentences. It is characteristic of fluent aphasia, most commonly receptive aphasia. Paragrammatism is sometimes called "extended paraphasia," although it is different from paraphasia. Paragrammatism is roughly synonymous with "word salad," which concerns the semantic coherence of speech rather than its production.

Auditory agnosia is a form of agnosia that manifests itself primarily in the inability to recognize or differentiate between sounds. It is not a defect of the ear or "hearing", but rather a neurological inability of the brain to process sound meaning. While auditory agnosia impairs the understanding of sounds, other abilities such as reading, writing, and speaking are not hindered. It is caused by bilateral damage to the anterior superior temporal gyrus, which is part of the auditory pathway responsible for sound recognition, the auditory "what" pathway.

Apraxia of speech (AOS), also called verbal apraxia, is a speech sound disorder affecting an individual's ability to translate conscious speech plans into motor plans, which results in limited and difficult speech ability. By the definition of apraxia, AOS affects volitional movement pattern. However, AOS usually also affects automatic speech.

Jargon aphasia is a type of fluent aphasia in which an individual's speech is incomprehensible, but appears to make sense to the individual. Persons experiencing this condition will either replace a desired word with another that sounds or looks like the original one, or has some other connection to it, or they will replace it with random sounds. Accordingly, persons with jargon aphasia often use neologisms, and may perseverate if they try to replace the words they can not find with sounds.

Music therapy for non-fluent aphasia is a method for treating patients who have lost the ability to speak after a stroke or accident. Non-fluent aphasia, also called expressive aphasia, is a neurological disorder that deprives patients of the ability to express language. It is usually caused by stroke or lesions in Broca's area, which is a language-dominant area that is responsible for speech production located in the left hemisphere of the brain. However, when lesions form in Broca's area this only affects patients’ speech ability, while their ability to sing remains unaffected. Since several studies have shown that right hemispheric regions are more active during singing, music therapy involving melodic elements is deemed to be a potential treatment for non-fluent aphasia, as singing might activate patients’ right hemisphere to compensate with their lesioned left hemisphere. Aside from singing, many other music therapy techniques have also been attempted such as rhythms and poetic emphasis, which is shown to add to the effectiveness. Although there are many possible explanations for the mechanism of music therapy, the underlying mechanism remains unclear, as some studies indicate contradictory results.

References

1 2 Manasco, Hunter (2014). Introduction to Neurogenic Communication Disorders. p. 73.
1 2 Biran M, Friedmann N (2005). "From phonological paraphasias to the structure of the phonological output lexicon". Language and Cognitive Processes. 20 (4): 589–616. CiteSeerX 10.1.1.69.7795 . doi:10.1080/01690960400005813. S2CID 14484194.
↑ Julius Althaus (1877). Diseases of the nervous system: their prevalence and pathology. Smith, Elder. p. 163.
1 2 3 4 5 Sinanovic O, Mrkonjic Z, Zukic S, Vidovic M, Imamovic K. 2011. Post-stroke language disorders. Acta clinica Croatica 50:79-94
1 2 3 Kreisler A, Godefroy O, Delmaire C, Debachy B, Leclercq M, et al. (2000). "The anatomy of aphasia revisited". Neurology. 54 (5): 1117–23. doi:10.1212/wnl.54.5.1117. PMID 10720284. S2CID 21847976.
↑ Rohrer JD, Knight WD, Warren JE, Fox NC, Rossor MN, Warren JD (2008). "Word-finding difficulty: a clinical analysis of the progressive aphasias". Brain. 131 (Pt 1): 8–38. doi:10.1093/brain/awm251. PMC 2373641 . PMID 17947337.
↑ Gallaher, Alan J. (Jun 24, 1981). "Syntactic versus semantic performances of agrammatic Broca's aphasics on tests of constituent-element-ordering". Journal of Speech and Hearing Research. 24 (2): 217–218. doi:10.1044/jshr.2402.217. PMID 7265937.
↑ Kellogg, Margaret Kimberly (2012). "Conceptual mechanisms underlying noun and verb categorization: Evidence from paraphasia". Proceedings of the Annual Meeting of the Berkeley Linguistics Society. 20 (1).
↑ Huber, Mary (1944). "A Phonetic Approach to the Problem of Perception in a Case of Wernicke's Aphasia". Journal of Speech, Language, and Hearing Research: 227–238.
1 2 Berg T (2006). "A structural account of phonological paraphasias". Brain and Language. 96 (3): 331–56. doi:10.1016/j.bandl.2006.01.005. PMID 16615177.
↑ Buckingham HW (1986). "The scan-copier mechanism and the positional level of language production: Evidence from phonemic paraphasia". Cognitive Science. 10 (2): 195–217. doi: 10.1207/s15516709cog1002_4 .
1 2 3 Corina DP, Loudermilk BC, Detwiler L, Martin RF, Brinkley JF, Ojemann G (2010). "Analysis of naming errors during cortical stimulation mapping: Implications for models of language representation". Brain and Language. 115 (2): 101–12. doi:10.1016/j.bandl.2010.04.001. PMC 3247200 . PMID 20452661.
↑ Caplan D, Kellar L, Locke S (1972). "Inflection of neologisms in aphasia". Brain. 95 (1): 169–72. doi: 10.1093/brain/95.1.169 . PMID 5023086.
1 2 3 4 Butterworth B (1979). "Hesitation and the production of verbal paraphasias and neologisms in jargon aphasia". Brain and Language. 8 (2): 133–61. doi:10.1016/0093-934x(79)90046-4. PMID 487066. S2CID 39339730.
↑ Garzon M, Semenza M, Meneghello F, Bencini G, Semenza C (2011). "Target-Unrelated Verbal Paraphasias: A Case Study" (PDF). Procedia - Social and Behavioral Sciences. 23: 142–3. doi: 10.1016/j.sbspro.2011.09.210 .
1 2 Lewis FC, Soares L (2000). "Relationship between Semantic Paraphasias and Related Nonverbal Factors". Perceptual and Motor Skills. 91 (2): 366–72. doi:10.2466/pms.2000.91.2.366. PMID 11065295. S2CID 755716.
↑ Boyle M. 1988. Reducing Phonemic Paraphasias in the Connected Speech of a Conduction Aphasic Subject. In Clinical Aphasiology Conference, pp. 379-93. Cape Cod, MA
↑ T. Picht, S. M. Krieg, N. Sollmann, J. Rösler, B. Niraula, T. Neuvonen, P. Savolainen, P. Lioumis, Pantelis, J. P. Mäkelä, V. Deletis, B. Meyer, P. Vajkoczy, and F. Ringel, A comparison of language mapping by preoperative navigated transcranial magnetic stimulation and direct cortical stimulation during awake surgery, Neurosurgery 72, 808–819 (2013).

Sources

"Aphasia: Characteristics". The Neuroscience on the Web Series.
"paraphasia - definition of paraphasia in the Medical dictionary - by the Free Online Medical Dictionary, Thesaurus and Encyclopedia".
"I Can't Come Up with the Right Word..." by William Barr, Ph.D., ABPP
Buckingham Hugh W., Rekart Deborah M. (1979). "Semantic paraphasia". Journal of Communication Disorders. 12 (3): 197–209. doi:10.1016/0021-9924(79)90041-8. PMID 438359.
ScienceDaily - 'Weapons Of Mass Production', I Mean, 'Mass Destruction!' How The Brain Prevents Verbal Errors, Nov 5, 2008
Science Daily - Area Of Brain Key To Choosing Words Identified, Dec 30, 2008

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[:0-1] 1 2 Manasco, Hunter (2014). Introduction to Neurogenic Communication Disorders. p. 73.

[biran-2] 1 2 Biran M, Friedmann N (2005). "From phonological paraphasias to the structure of the phonological output lexicon". Language and Cognitive Processes. 20 (4): 589–616. CiteSeerX 10.1.1.69.7795 . doi:10.1080/01690960400005813. S2CID 14484194.

[3] Julius Althaus (1877). Diseases of the nervous system: their prevalence and pathology. Smith, Elder. p. 163.

[sinanovic-4] 1 2 3 4 5 Sinanovic O, Mrkonjic Z, Zukic S, Vidovic M, Imamovic K. 2011. Post-stroke language disorders. Acta clinica Croatica 50:79-94

[kreisler-5] 1 2 3 Kreisler A, Godefroy O, Delmaire C, Debachy B, Leclercq M, et al. (2000). "The anatomy of aphasia revisited". Neurology. 54 (5): 1117–23. doi:10.1212/wnl.54.5.1117. PMID 10720284. S2CID 21847976.

[rohrer-6] Rohrer JD, Knight WD, Warren JE, Fox NC, Rossor MN, Warren JD (2008). "Word-finding difficulty: a clinical analysis of the progressive aphasias". Brain. 131 (Pt 1): 8–38. doi:10.1093/brain/awm251. PMC 2373641 . PMID 17947337.

[7] Gallaher, Alan J. (Jun 24, 1981). "Syntactic versus semantic performances of agrammatic Broca's aphasics on tests of constituent-element-ordering". Journal of Speech and Hearing Research. 24 (2): 217–218. doi:10.1044/jshr.2402.217. PMID 7265937.

[8] Kellogg, Margaret Kimberly (2012). "Conceptual mechanisms underlying noun and verb categorization: Evidence from paraphasia". Proceedings of the Annual Meeting of the Berkeley Linguistics Society. 20 (1).

[9] Huber, Mary (1944). "A Phonetic Approach to the Problem of Perception in a Case of Wernicke's Aphasia". Journal of Speech, Language, and Hearing Research: 227–238.

[berg-10] 1 2 Berg T (2006). "A structural account of phonological paraphasias". Brain and Language. 96 (3): 331–56. doi:10.1016/j.bandl.2006.01.005. PMID 16615177.

[buckingham-11] Buckingham HW (1986). "The scan-copier mechanism and the positional level of language production: Evidence from phonemic paraphasia". Cognitive Science. 10 (2): 195–217. doi: 10.1207/s15516709cog1002_4 .

[corina-12] 1 2 3 Corina DP, Loudermilk BC, Detwiler L, Martin RF, Brinkley JF, Ojemann G (2010). "Analysis of naming errors during cortical stimulation mapping: Implications for models of language representation". Brain and Language. 115 (2): 101–12. doi:10.1016/j.bandl.2010.04.001. PMC 3247200 . PMID 20452661.

[caplan-13] Caplan D, Kellar L, Locke S (1972). "Inflection of neologisms in aphasia". Brain. 95 (1): 169–72. doi: 10.1093/brain/95.1.169 . PMID 5023086.

[butterworth-14] 1 2 3 4 Butterworth B (1979). "Hesitation and the production of verbal paraphasias and neologisms in jargon aphasia". Brain and Language. 8 (2): 133–61. doi:10.1016/0093-934x(79)90046-4. PMID 487066. S2CID 39339730.

[garzon-15] Garzon M, Semenza M, Meneghello F, Bencini G, Semenza C (2011). "Target-Unrelated Verbal Paraphasias: A Case Study" (PDF). Procedia - Social and Behavioral Sciences. 23: 142–3. doi: 10.1016/j.sbspro.2011.09.210 .

[lewis-16] 1 2 Lewis FC, Soares L (2000). "Relationship between Semantic Paraphasias and Related Nonverbal Factors". Perceptual and Motor Skills. 91 (2): 366–72. doi:10.2466/pms.2000.91.2.366. PMID 11065295. S2CID 755716.

[17] Boyle M. 1988. Reducing Phonemic Paraphasias in the Connected Speech of a Conduction Aphasic Subject. In Clinical Aphasiology Conference, pp. 379-93. Cape Cod, MA

[picht-18] T. Picht, S. M. Krieg, N. Sollmann, J. Rösler, B. Niraula, T. Neuvonen, P. Savolainen, P. Lioumis, Pantelis, J. P. Mäkelä, V. Deletis, B. Meyer, P. Vajkoczy, and F. Ringel, A comparison of language mapping by preoperative navigated transcranial magnetic stimulation and direct cortical stimulation during awake surgery, Neurosurgery 72, 808–819 (2013).

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