Aprosodia

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Aprosodia is a neurological condition characterized by the inability of a person to properly convey or interpret emotional prosody. Prosody in language refers to the ranges of rhythm, pitch, stress, intonation, etc. These neurological deficits can be the result of damage of some form to the non-dominant hemisphere areas of language production. The prevalence of aprosodias in individuals is currently unknown, as testing for aprosodia secondary to other brain injury is only a recent occurrence.

Contents

Types

Productive

Receptive

Receptive aprosodia can result from impairment at one or more sensory and/or cognitive levels ranging from hearing (signal acquisition) to auditory processing (signal isolation) to emotional comprehension (signal interpretation). For example, the first two difficulties impair an individual's ability to observe and discern changes in stress and intonation, whereas the third impairs an individual's ability to assess the significance of those stress and intonation changes that he or she correctly observes and discerns; impairment of the third type correlates significantly with expressive aprosodia. [3]

Mixed

Mixed aprosodia is characterized by the exhibition of more than one of the above specific subtypes of aprosodia, with the degree of impairment exhibited by a given person often differing from subtype to subtype.[ citation needed ]

Presentation

Impact

The loss of ability to express and understand emotions is debilitating to those experiencing aprosodia. It has a large impact on their lives and affects their day-to-day interactions with others. While it is often overlooked, affective prosody is as integral to communication as the ability to form and understand correct words. Patients exhibiting extreme cases of aprosodia speak in a monotone fashion and are barely able or unable to distinguish changes in stress or intonation.[ citation needed ]

Causes

Localized brain damage

One cause of aprosodia is trauma to one of several specific areas of the brain, resulting in the inability to properly process or convey emotional cues. This brain damage can occur in the form of ischemic damage from stroke, [4] removal during surgery, brain lesions, or trauma such as a localized bullet wound. It is worth noting however, that this localization occurs over a range of areas that can vary from person to person and more research is required to further define these areas. Diagnostic confirmation of aprosodia using brain scanning techniques is a relatively recent occurrence, at least with respect to quantitative specificity. [2] As brain imaging techniques are refined to allow for greater temporal and spatial resolution, it is hoped that more will be able to be learned about aprosodias at a functional anatomical level.[ citation needed ]

Alcohol use disorder

An inability to process or exhibit emotions in a proper manner has been shown to exist in people who consume excessive amounts of alcohol and those who were exposed to alcohol while fetuses (FAexp). Initially, when people with an alcohol use disorder are detoxified and FAexp individuals were tested for impairment in cognitive function, it was limited to testing the non-affective aspects of language, as those were the more easily recognized by a physician not trained in analyzing affective prosody. When tested using the aprosodia battery, it was found that those with alcohol use disorder who detoxified and FAexp individuals demonstrated significant impairment in their ability to detect affective prosody when used by others. The major factors which influence affective prosody in those impacted by alcohol use, from greatest to least impact, are: alcohol use by mother, age at onset of chronic abuse of alcohol, age at initial abuse, how chronic the abuse is, and the age when a person first becomes drunk. [5]

Aprosodia as a symptom

Aprosodia has also been shown to appear secondary to several diseases such as multiple sclerosis or post traumatic stress disorder. [6] It is likely that as time passes more diseases will be shown to exhibit aprosodia as a symptom. Aprosodia is a condition that was not often tested for in the presence of neurological deficits; however, as more becomes known about it, the aprosodia battery will likely be administered more frequently. For example, the first study testing for aprosodia in MS did not occur until 2009. [7] This is surprising given that changes in emotional affect would be expected to be noticed in patients exhibiting other changes in speech patterns. This is especially so given that the patients tested in these studies scored poorer than the controls by a statistically significant amount.[ citation needed ]

Diagnosis

Emotional batteries

Emotional batteries consist of asking patients to read various sentences with specific emotional indicators. Their performance is subjectively analyzed by an expert to determine if they are aprosodic. The analysis is often performed by two experts independently, with one of the judges not being present during the interview in case the patient was still able to use facial cues. [8]

Assessment questionnaire

Another method implemented to test for aprosodia involves having questionnaires filled out by those close to the patient. The doctors and nurses taking care of a patient are also requested to fill out a questionnaire if aprosodia is suspected. This diagnosis method occurs more as an indicator that the aprosodia battery should be administered rather than being used as a singular diagnosis tool. Implementation of the questionnaire is expected to become more widespread as aprosodia is revealed to be a side-effect of more diseases. [8]

Aprosodia vs. dysprosody

Brain imaging studies related to speech functions have yielded insights into the subtle difference between aprosodia and dysprosody. The major differences in these result from functions which are characterized as belonging mainly to the left or right hemisphere. Several of the functions have been described as dominant and lateralized functions of the corresponding hemispheres, while some have been found to arise from communication between the two hemispheres. [1] While the ability to express or be receptive to affective prosody is similar in dysprosody and aprosodia, a significant difference in the characterization of them is dominant vs. non-dominant hemispherical damage.[ citation needed ]

Treatment

Due to the rarity of reported aprosodia cases, only a few labs are currently researching treatment methods of aprosodia. The largest study of treatments for aprosodia consisted of only fourteen individuals, resulting in sample sizes too small to report statistical significance when comparing one treatment to another. However, the data gained from this study still yielded some results and is being used in the next iteration of aprosodia research.[ citation needed ]

Methods

The two main forms of treatment are cognition based and imitation based. Cognitive treatments attempt to rebuild the "emotional toolbox" of those with aprosodia. The basis for this treatment is the belief that there exists a defined set of emotional responses that can be chosen for a given scenario. Choosing the proper emotional response can very much be likened to choosing the proper word when describing an object, and this deficiency can be likened to Broca's Aphasia but for emotions. Imitative treatments attempt to help "kickstart" the motor systems involved in the production of both vocal and facial emotive gestures. The basis for this treatment is the belief that the pathways responsible for the motor elements of expressive prosody were damaged. It is hypothesized that the motor damage occurs at the level of planning as well as the level of execution. [9]

Progress

The methods of treatment are being evaluated and changed through several iterations to reach the most beneficial treatment for those with aprosodia. Although the biggest limitation on progress of aprosodia treatment is sample size, some significant data has been found to influence each subsequent phase of study. The Rosenbek lab at the University of Florida is currently in a new phase of treatment study based on combinations of the cognitive-linguistic and imitative therapies delivered in a randomized fashion in an effort to gain more insight into what most prominently affects aprosodia treatment. [8]

Research

Research into the perisylvan region of the right hemisphere has shown that there are similarly mapped analogues to the speech center in the left hemisphere. This is especially evident in those areas resembling Broca's area and Wernicke's area. [10] The similarity of these regions has led scientists to view aprosodias in a similar manner to how some aphasias are viewed. Because the presence of an aphasia is often more pronounced in an individual than an aprosodia might be, aphasias have traditionally been more heavily studied. Because aphasias are rooted in deficiencies in language modalities rather than affective aspects of language, it has been easier to characterize the underlying impairment caused by brain damage (e.g. inability to choose the right word or inability to speak due to motor control). Combining aphasic research with right-left analogue mapping has allowed for researchers to produce hypotheses on the underlying process behind various aprosodias.[ citation needed ]

Additionally, in studying the brain regions associated with aprosodia, brain imaging tests were performed to determine if aprosodia is both a lateralized and dominant function of the right hemisphere areas of language production. Aprosodia can be considered a dominant function of the right hemisphere because strong correlation was found between deficits in affective prosody and distribution of lesions in the cortices of those with right brain damage. No correlation was found between the distribution of cortical lesions in patients with left brain damage and the types of aphasic deficits pronounced in those patients. Aprosodia can be considered a lateralized function of the right hemisphere because of the differences in the ability of a patient to respond to affective prosodic information in those with left brain damage when compared to those with right brain damage. Patients with affective-prosodic deficits in the left hemisphere (dysprosodic patients) showed improvement in understanding and repeating prosodic information when other conveyed linguistic information was simplified, i.e. requiring the patient to mainly determine prosodic information contained in an interaction. This improvement in processing affective prosodic information under reduced linguistic processing demands did not occur for patients with right brain damage. [1]

See also

Related Research Articles

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

In aphasia, a person is 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, brain infections, or neurodegenerative diseases.

<span class="mw-page-title-main">Expressive aphasia</span> Language disorder involving inability to produce language

Expressive aphasia, also known as Broca's 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.

<span class="mw-page-title-main">Receptive aphasia</span> Language disorder involving inability to understand language

Wernicke's aphasia, also known as receptive aphasia, sensory 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 are typically 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.

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.

Anosognosia is a condition in which a person with a disability is cognitively unaware of having it due to an underlying physical or psychological condition. Anosognosia can result from physiological damage to brain structures, typically to the parietal lobe or a diffuse lesion on the fronto-temporal-parietal area in the right hemisphere, and is thus a neuropsychiatric disorder. A deficit of self-awareness, it was first named by the neurologist Joseph Babinski in 1914. Phenomenologically, anosognosia has similarities to denial, which is a psychological defense mechanism; attempts have been made at a unified explanation. Anosognosia is sometimes accompanied by asomatognosia, a form of neglect in which patients deny ownership of body parts such as their limbs. The term is from Ancient Greek ἀ- a-, 'without', νόσος nosos, 'disease' and γνῶσις gnōsis, 'knowledge'. It is also considered a disorder that makes the treatment of the patient more difficult, since it may affect negatively the therapeutic relationship.

<span class="mw-page-title-main">Global aphasia</span> Medical condition

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.

In linguistics, prosody is the study of elements of speech that are not individual phonetic segments but which are properties of syllables and larger units of speech, including linguistic functions such as intonation, stress, and rhythm. Such elements are known as suprasegmentals.

Amusia is a musical disorder that appears mainly as a defect in processing pitch but also encompasses musical memory and recognition. Two main classifications of amusia exist: acquired amusia, which occurs as a result of brain damage, and congenital amusia, which results from a music-processing anomaly present since birth.

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.

<span class="mw-page-title-main">Mixed transcortical aphasia</span>

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.

<span class="mw-page-title-main">Lateralization of brain function</span> Specialization of some cognitive functions in one side of the brain

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.

<span class="mw-page-title-main">Frontal lobe disorder</span> Brain disorder

Frontal lobe disorder, also frontal lobe syndrome, is an impairment of the frontal lobe of the brain due to disease or frontal lobe injury. The frontal lobe plays a key role in executive functions such as motivation, planning, social behaviour, and speech production. Frontal lobe syndrome can be caused by a range of conditions including head trauma, tumours, neurodegenerative diseases, neurodevelopmental disorders, neurosurgery and cerebrovascular disease. Frontal lobe impairment can be detected by recognition of typical signs and symptoms, use of simple screening tests, and specialist neurological testing.

Dysprosody, which may manifest as pseudo-foreign accent syndrome, refers to a disorder in which one or more of the prosodic functions are either compromised or eliminated.

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.

Emotional lateralization is the asymmetrical representation of emotional control and processing in the brain. There is evidence for the lateralization of other brain functions as well.

<span class="mw-page-title-main">Right hemisphere brain damage</span> Medical condition

Right hemisphere brain damage (RHD) is the result of injury to the right cerebral hemisphere. The right hemisphere of the brain coordinates tasks for functional communication, which include problem solving, memory, and reasoning. Deficits caused by right hemisphere brain damage vary depending on the location of the damage.

Cerebellar cognitive affective syndrome (CCAS), also called Schmahmann's syndrome is a condition that follows from lesions (damage) to the cerebellum of the brain. It refers to a constellation of deficits in the cognitive domains of executive function, spatial cognition, language, and affect resulting from damage to the cerebellum. Impairments of executive function include problems with planning, set-shifting, abstract reasoning, verbal fluency, and working memory, and there is often perseveration, distractibility and inattention. Language problems include dysprosodia, agrammatism and mild anomia. Deficits in spatial cognition produce visual–spatial disorganization and impaired visual–spatial memory. Personality changes manifest as blunting of affect or disinhibited and inappropriate behavior. These cognitive impairments result in an overall lowering of intellectual function. CCAS challenges the traditional view of the cerebellum being responsible solely for regulation of motor functions. It is now thought that the cerebellum is responsible for monitoring both motor and nonmotor functions. The nonmotor deficits described in CCAS are believed to be caused by dysfunction in cerebellar connections to the cerebral cortex and limbic system.

Emotional prosody or affective prosody is the various non-verbal aspects of language that allow people to convey or understand emotion. It includes an individual's tone of voice in speech that is conveyed through changes in pitch, loudness, timbre, speech rate, and pauses. It can be isolated from semantic information, and interacts with verbal content.

Body part as object (BPO) mime gestures occurs when an individual substitutes a part of their body - usually arms, fingers, or hands - to be part of an object they are miming. Miming uses representational gestures, meaning they are used to convey a message to others without the use of speech. A commonly used example of BPO miming is demonstrated by an individual using their finger to represent a toothbrush while acting out brushing their teeth.

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 responsible for speech production in the left hemisphere. However, lesions in Broca’s area 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 and the effectiveness of some techniques is shown. 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. 1 2 3 Ross, E. D., & Monnot, M. (2008). Neurology of affective prosody and its functional-anatomic organization in right hemisphere. [Review]. Brain and Language, 104(1), 51-74.
  2. 1 2 Williamson, J. B., Harrison, D. W., Shenal, B. V., Rhodes, R., & Demaree, H. A. (2003). Quantitative EEG diagnostic confirmation of expressive aprosodia. [Article]. Applied Neuropsychology, 10(3), 176-181.
  3. ↑ Raithel, V. (2005). Perception of Intonation Contours and Focus by Aphasic and Healthy Individuals [Book]. pp. 28-29.
  4. ↑ Heilman, K. M., Leon, S. A., & Rosenbek, J. C. (2004). Affective aprosodia from a medial frontal stroke.[Article]. Brain and Language, 89(3), 411-416
  5. ↑ Monnot, M., Nixon, S., Lovallo, W., & Ross, E. (2001). Altered emotional perception in alcoholics: Deficits in affective prosody comprehension. [Article]. Alcoholism: Clinical and Experimental Research, 25(3), 362-369.
  6. ↑ Freeman, T. W., Hart, J., Kimbrell, T., & Ross, E. D. (2009). Comprehension of Affective Prosody in Veterans With Chronic Posttraumatic Stress Disorder. [Article]. Journal of Neuropsychiatry and Clinical Neurosciences, 21(1), 52-58.
  7. ↑ Beatty, W. W., Orbelo, D. M., Sorocco, K. H., & Ross, E. D. (2003). Comprehension of affective prosody in multiple sclerosis. [Article]. Multiple Sclerosis, 9(2), 148-153.
  8. 1 2 3 Rosenbek, J. C. (2009, October 6). Chair - Department of Communicative Disorders, University of Florida. [Telephone interview]
  9. ↑ Rosenbek, J. C., Rodriguez, A. D., Hieber, B., Leon, S. A., Crucian, G. P., Ketterson, T. U., et al. (2006). Effects of two treatments for aprosodia secondary to acquired brain injury. [Article]. Journal of Rehabilitation Research and Development 43(3), 379-390.
  10. ↑ Bookheimer, S. (2002). Functional MRI of language: New approaches to understanding the cortical organization of semantic processing. [Review]. Annual Review of Neuroscience, 25, 151-188.
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