Aprosodia
A neurological inability to produce or interpret emotional speech cues.
Aprosodia is a neurological condition marked by difficulty in conveying or interpreting emotional prosody—the rhythm, pitch, stress, and intonation of speech. It typically results from damage to the non-dominant hemisphere's language production areas. The condition's prevalence remains uncertain because systematic testing for aprosodia following brain injury has only recently been adopted.
Quick Facts
- Primary treatment research lab
- Rosenbek lab at the University of Florida
Facts from the source article.
Causes
Trauma to specific brain areas can cause aprosodia by disrupting the processing or conveyance of emotional cues, with ischemic damage from stroke being one form of such injury. People who consume excessive alcohol or were exposed to it as fetuses (FAexp) have shown impaired ability to detect affective prosody when tested with the aprosodia battery, though earlier testing focused only on non-affective language aspects. The factors influencing affective prosody in those affected by alcohol use, ranked from greatest to least impact, are: alcohol use by mother, age at onset of chronic abuse, age at initial abuse, how chronic the abuse is, and age at first intoxication. Aprosodia also appears secondary to diseases such as multiple sclerosis and post-traumatic stress disorder, and it is likely that more conditions will be found to exhibit it as testing becomes more common. The first study examining aprosodia in multiple sclerosis was conducted in 2009.
Diagnosis
Diagnosis involves emotional batteries where patients read sentences with specific emotional indicators, and their performance is subjectively analyzed by experts, often two independently, with one judge not present during the interview to avoid reliance on facial cues. Questionnaires filled out by those close to the patient, as well as by doctors and nurses, serve as an indicator that the aprosodia battery should be administered rather than as a standalone diagnostic tool. Brain imaging studies of speech functions have helped distinguish aprosodia from dysprosody, with differences arising from functions lateralized to the left or right hemisphere or from interhemispheric communication.
Treatment
Two main treatment approaches exist: cognitive and imitative. Cognitive treatments aim to rebuild an emotional toolbox, based on the idea that a defined set of emotional responses can be selected for a given scenario, analogous to choosing words in Broca's aphasia. Imitative treatments seek to kickstart motor systems involved in vocal and facial emotive gestures, assuming damage occurred at the planning or execution level of motor pathways. Treatment methods are refined through iterative studies, with sample size being the major limitation. The Rosenbek lab at the University of Florida is currently investigating combinations of cognitive-linguistic and imitative therapies delivered randomly to better understand what most affects treatment outcomes.
Research
Research into the right hemisphere's perisylvian region has revealed mapped analogues to left-hemisphere speech centers, particularly areas resembling Broca's and Wernicke's areas. Brain imaging studies have shown that aprosodia can be considered a dominant function of the right hemisphere, as a strong correlation exists between deficits in affective prosody and lesion distribution in the right cortices, whereas no such correlation appears for left-hemisphere damage and aphasic deficits. Aprosodia is also a lateralized function: patients with left-brain damage (dysprosody) improved in understanding prosodic information when linguistic demands were simplified, but those with right-brain damage did not show this improvement.
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