Affective Prosody and Its Impact on the Neurology of Language, Depression, Memory and Emotions

Based on the seminal publications of Paul Broca and Carl Wernicke who established that aphasic syndromes (disorders of the verbal-linguistic aspects of communication) were predominantly the result of focal left-hemisphere lesions, "language" is traditionally viewed as a lateralized function of the left hemisphere. This, in turn, has diminished and delayed the acceptance that the right hemisphere also has a vital role in language, specifically in modulating affective prosody, which is essential for communication competency and psychosocial well-being. Focal lesions of the right hemisphere may result in disorders of affective prosody (aprosodic syndromes) that are functionally and anatomically analogous to the aphasic syndromes that occur following focal left-hemisphere lesions. This paper will review the deductive research published over the last four decades that has elucidated the neurology of affective prosody which, in turn, has led to a more complete and nuanced understanding of the neurology of language, depression, emotions and memory. In addition, the paper will also present the serendipitous clinical observations (inductive research) and fortuitous inter-disciplinary collaborations that were crucial in guiding and developing the deductive research processes that culminated in the concept that primary emotions and related display behaviors are a lateralized function of the right hemisphere and social emotions, and related display behaviors are a lateralized function of the left hemisphere.

Affective prosody disorders in adults with neurological conditions: A scoping review

BACKGROUND

Individuals with affective-prosodic deficits have difficulty understanding or expressing emotions and attitudes through prosody. Affective prosody disorders can occur in multiple neurological conditions, but the limited knowledge about the clinical groups prone to deficits complicates their identification in clinical settings. Additionally, the nature of the disturbance underlying affective prosody disorder observed in different neurological conditions remains poorly understood.

AIMS

To bridge these knowledge gaps and provide relevant information to speech-language pathologists for the management of affective prosody disorders, this study provides an overview of research findings on affective-prosodic deficits in adults with neurological conditions by answering two questions: (1) Which clinical groups present with acquired affective prosodic impairments following brain damage? (2) Which aspects of affective prosody comprehension and production are negatively affected in these neurological conditions?

METHODS & PROCEDURES

We conducted a scoping review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews guidelines. A literature search was undertaken in five electronic databases (MEDLINE, PsycINFO, EMBASE, CINAHL and Linguistics, and Language Behavior Abstracts) to identify primary studies reporting affective prosody disorders in adults with neurological impairments. We extracted data on clinical groups and characterised their deficits based on the assessment task used.

OUTCOMES & RESULTS

The review of 98 studies identified affective-prosodic deficits in 17 neurological conditions. The task paradigms typically used in affective prosody research (discrimination, recognition, cross-modal integration, production on request, imitation and spontaneous production) do not target the processes underlying affective prosody comprehension and production. Therefore, based on the current state of knowledge, it is not possible to establish the level of processing at which impairment occurs in clinical groups. Nevertheless, deficits in the comprehension of affective prosody are observed in 14 clinical groups (mainly recognition deficits) and deficits in the production of affective prosody (either on request or spontaneously) in 10 clinical groups. Neurological conditions and types of deficits that have not been investigated in many studies are highlighted.

CONCLUSIONS & IMPLICATIONS

The aim of this scoping review was to provide an overview on acquired affective prosody disorders and to identify gaps in knowledge that warrant further investigation. Deficits in the comprehension or production of affective prosody are common to numerous clinical groups with various neurological conditions. However, the underlying cause of affective prosody disorders across them is still unknown. Future studies should implement standardised assessment methods with specific tasks based on a cognitive model to identify the underlying deficits of affective prosody disorders.

WHAT THIS PAPER ADDS

What is already known on the subject What is already known on the subjectAffective prosody is used to share emotions and attitudes through speech and plays a fundamental role in communication and social interactions. Affective prosody disorders can occur in various neurological conditions, but the limited knowledge about the clinical groups prone to affective-prosodic deficits and about the characteristics of different phenotypes of affective prosody disorders complicates their identification in clinical settings. Distinct abilities underlying the comprehension and production of affective prosody can be selectively impaired by brain damage, but the nature of the disturbance underlying affective prosody disorders in different neurological conditions remains unclear. What this study adds Affective-prosodic deficits are reported in 17 neurological conditions, despite being recognised as a core feature of the clinical profile in only a few of them. The assessment tasks typically used in affective prosody research do not provide accurate information about the specific neurocognitive processes impaired in the comprehension or production of affective prosody. Future studies should implement assessment methods based on a cognitive approach to identify underlying deficits. The assessment of cognitive/executive dysfunctions, motor speech impairment and aphasia might be important for distinguishing primary affective prosodic dysfunctions from those secondarily impacting affective prosody. What are the potential clinical implications of this study? Raising awareness about the possible presence of affective-prosodic disorders in numerous clinical groups will facilitate their recognition by speech-language pathologists and, consequently, their management in clinical settings. A comprehensive assessment covering multiple affective-prosodic skills could highlight specific aspects of affective prosody that warrant clinical intervention.

The Company Prosodic Deficits Keep Following Right Hemisphere Stroke: A Systematic Review

OBJECTIVES

The aim of this systematic review was to identify the presence and nature of relationships between specific forms of aprosodia (i.e., expressive and receptive emotional and linguistic prosodic deficits) and other cognitive-communication deficits and disorders in individuals with right hemisphere damage (RHD) due to stroke.

METHODS

One hundred and ninety articles from 1970 to February 2020 investigating receptive and expressive prosody in patients with relatively focal right hemisphere brain damage were identified via database searches.

RESULTS

Fourteen articles were identified that met inclusion criteria, passed quality reviews, and included sufficient information about prosody and potential co-occurring deficits. Twelve articles investigated receptive emotional aprosodia, and two articles investigated receptive linguistic aprosodia. Across the included studies, receptive emotional prosody was not systematically associated with hemispatial neglect, but did co-occur with deficits in emotional facial recognition, interpersonal interactions, or emotional semantics. Receptive linguistic processing was reported to co-occur with amusia and hemispatial neglect. No studies were found that investigated the co-occurrence of expressive emotional or linguistic prosodic deficits with other cognitive-communication impairments.

CONCLUSIONS

This systematic review revealed significant gaps in the research literature regarding the co-occurrence of common right hemisphere disorders with prosodic deficits. More rigorous empirical inquiry is required to identify specific patient profiles based on clusters of deficits associated with right hemisphere stroke. Future research may determine whether the co-occurrences identified are due to shared cognitive-linguistic processes, and may inform the development of evidence-based assessment and treatment recommendations for individuals with cognitive-communication deficits subsequent to RHD.

Assessment tools and rehabilitation treatments for aprosodia following acquired brain injury: A scoping review

BACKGROUND

Acquired brain injury (ABI), especially to the right hemisphere, can result in difficulty using or understanding prosodic contours in speech. Prosody is used to convey emotional connotation or linguistic intent and includes pitch, loudness, rate, and voice quality. A disorder in the comprehension or production of prosody is known as aprosodia; despite the communication disability caused by prosodic disorders, the assessment and treatment of aprosodia following ABI has received scant attention.

AIMS

The aim of this scoping review is to gather and synthesise useful knowledge on aprosodia and provide therapists with an exhaustive document in order to guide clinical decision-making encouraging active identification and treatment of this disorder.

METHODS & PROCEDURES

This scoping review, conducted in accordance with PRISMA-ScR guidelines, investigated the existing literature concerning the assessment and treatments of linguistic and affective aprosodia in adult patients after ABI. A systematic search in four electronic databases (PubMed, CINAHL, Web of Science, ScienceDirect) was conducted for articles written in English, French, or Italian published between 1970 and 2020. After all evaluative criteria were applied, 15 articles were included for final review.

OUTCOMES & RESULTS

Results show the presence of six assessment tools for affective aprosodia and five evaluation tools targeting affective and linguistic prosody. Assessment of aprosodia is generally accomplished through acoustic and perceptual approaches. Current treatments for prosodic disorders focus on expressive aprosodia and have applied mostly two different approaches: imitative and cognitive-linguistic methods.

CONCLUSION & IMPLICATIONS

Findings suggest that aprosodia can be assessed by therapists through various techniques and may be amenable to behavioural treatments. Nevertheless, although there are several assessment tools available, no one currently offers a comprehensive assessment that incorporates an ecological dimension. It therefore seems necessary to continue research in this direction. The rehabilitation of receptive prosody abilities also remains to be explored.

WHAT THIS PAPER ADDS

What is already known on the subject Prosody has a fundamental role in communication and conveys speakers' intentions and emotions. Therefore, a deficit of prosody (aprosodia) after acquired brain injury can reduce social participation and engagement. Assessment tools and rehabilitation treatments are necessary in order to improve this disorder and patients' quality of life. What this paper adds to existing knowledge The evaluation tools currently available focuses mostly on affective aprosodia, whereas the linguistic prosody is less assessed. There exist two treatments for expressive aprosodia: motoric-imitative and cognitive-linguistic treatments; however, their efficacy is tested on small groups of patients. No treatments targeting receptive aprosodia were found. What are the potential or actual clinical implications of this work? We need more sensitive and reliable tools and systematic evaluations of all the components of prosody (affective and linguistic, receptive and expressive prosody). We need researches who analyse bigger samples of patients after right hemisphere brain injury and we identified the need of more well-designed studies and better understanding of the pathophysiology of aprosodia.

Right ventral stream damage underlies both poststroke aprosodia and amusia

BACKGROUND AND PURPOSE

This study was undertaken to determine and compare lesion patterns and structural dysconnectivity underlying poststroke aprosodia and amusia, using a data-driven multimodal neuroimaging approach.

METHODS

Thirty-nine patients with right or left hemisphere stroke were enrolled in a cohort study and tested for linguistic and affective prosody perception and musical pitch and rhythm perception at subacute and 3-month poststroke stages. Participants listened to words spoken with different prosodic stress that changed their meaning, and to words spoken with six different emotions, and chose which meaning or emotion was expressed. In the music tasks, participants judged pairs of short melodies as the same or different in terms of pitch or rhythm. Structural magnetic resonance imaging data were acquired at both stages, and machine learning-based lesion-symptom mapping and deterministic tractography were used to identify lesion patterns and damaged white matter pathways giving rise to aprosodia and amusia.

RESULTS

Both aprosodia and amusia were behaviorally strongly correlated and associated with similar lesion patterns in right frontoinsular and striatal areas. In multiple regression models, reduced fractional anisotropy and lower tract volume of the right inferior fronto-occipital fasciculus were the strongest predictors for both disorders, over time.

CONCLUSIONS

These results highlight a common origin of aprosodia and amusia, both arising from damage and disconnection of the right ventral auditory stream integrating rhythmic-melodic acoustic information in prosody and music. Comorbidity of these disabilities may worsen the prognosis and affect rehabilitation success.