Effects of prosody on the cognitive and neural resources supporting sentence comprehension: A behavioral and lesion-symptom mapping study

Beyond Broca: neural architecture and evolution of a dual motor speech coordination system

Classical neural architecture models of speech production propose a single system centred on Broca's area coordinating all the vocal articulators from lips to larynx. Modern evidence has challenged both the idea that Broca's area is involved in motor speech coordination and that there is only one coordination network. Drawing on a wide range of evidence, here we propose a dual speech coordination model in which laryngeal control of pitch-related aspects of prosody and song are coordinated by a hierarchically organized dorsolateral system while supralaryngeal articulation at the phonetic/syllabic level is coordinated by a more ventral system posterior to Broca's area. We argue further that these two speech production subsystems have distinguishable evolutionary histories and discuss the implications for models of language evolution.

Speech prosody supports speaker selection and auditory stream segregation in a multi-talker situation

To process speech in a multi-talker environment, listeners need to segregate the mixture of incoming speech streams and focus their attention on one of them. Potentially, speech prosody could aid the segregation of different speakers, the selection of the desired speech stream, and detecting targets within the attended stream. For testing these issues, we recorded behavioral responses and extracted event-related potentials and functional brain networks from electroencephalographic signals recorded while participants listened to two concurrent speech streams, performing a lexical detection and a recognition memory task in parallel. Prosody manipulation was applied to the attended speech stream in one group of participants and to the ignored speech stream in another group. Naturally recorded speech stimuli were either intact, synthetically F0-flattened, or prosodically suppressed by the speaker. Results show that prosody - especially the parsing cues mediated by speech rate - facilitates stream selection, while playing a smaller role in auditory stream segmentation and target detection.

The Development of Left Hemisphere Lateralization for Sentence-Level Prosodic Processing

PURPOSE

The fine-tuning of linguistic prosody in later childhood is poorly understood, and its neurological processing is even less well studied. In particular, it is unknown if grammatical processing of prosody is left- or right-lateralized in childhood versus adulthood and how phonological working memory might modulate such lateralization. Furthermore, it is virtually unknown how prosody develops neurologically among children with cochlear implants (CIs).

METHOD

Normal-hearing (NH) children ages 6-12 years and NH adults ages 18-28 years completed a functional near-infrared spectroscopy neuroimaging task, during which they heard sentence pairs and judged whether the sentences did or did not differ in their overall prosody (declarative, question, with or without narrow focus). Children also completed standard measures of expressive and receptive language.

RESULTS

Age group differences emerged; children exhibited stronger bilateral temporoparietal activity but reduced left frontal activation. Furthermore, children's performance on a nonword repetition test was significantly associated with activation in the left inferior frontal gyrus-an area that was generally more activated in adults than in children.

CONCLUSIONS

The prosody-related findings are generally consistent with prior neurodevelopmental works on sentence comprehension, especially those involving syntax and semantics, which have also noted a developmental shift from bilateral temporal to left inferior frontal regions typically associated with increased sensitivity to sentence structure. The findings thus inform theoretical perspectives on brain and language development and have implications for studying the effects of CIs on neurodevelopmental processes for sentence prosody.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.22255996.

Perception of Prosody in Hearing-Impaired Individuals and Users of Hearing Assistive Devices: An Overview of Recent Advances

PURPOSE

Prosody perception is an essential component of speech communication and social interaction through which both linguistic and emotional information are conveyed. Considering the importance of the auditory system in processing prosody-related acoustic features, the aim of this review article is to review the effects of hearing impairment on prosody perception in children and adults. It also assesses the performance of hearing assistive devices in restoring prosodic perception.

METHOD

Following a comprehensive online database search, two lines of inquiry were targeted. The first summarizes recent attempts toward determining the effects of hearing loss and interacting factors such as age and cognitive resources on prosody perception. The second analyzes studies reporting beneficial or detrimental impacts of hearing aids, cochlear implants, and bimodal stimulation on prosodic abilities in people with hearing loss.

RESULTS

The reviewed studies indicate that hearing-impaired individuals vary widely in perceiving affective and linguistic prosody, depending on factors such as hearing loss severity, chronological age, and cognitive status. In addition, most of the emerging information points to limitations of hearing assistive devices in processing and transmitting the acoustic features of prosody.

CONCLUSIONS

The existing literature is incomplete in several respects, including the lack of a consensus on how and to what extent hearing prostheses affect prosody perception, especially the linguistic function of prosody, and a gap in assessing prosody under challenging listening situations such as noise. This review article proposes directions that future research could follow to provide a better understanding of prosody processing in those with hearing impairment, which may help health care professionals and designers of assistive technology to develop innovative diagnostic and rehabilitation tools.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.21809772.

A systematic review on production and comprehension of linguistic prosody in people with acquired language and communication disorders resulting from unilateral brain lesions

BACKGROUND

Prosody serves central functions in language processing including linguistic functions (linguistic prosody), like structuring the speech signal. Impairments in production and comprehension of linguistic prosody have been described for persons with unilateral right (RHDP) or left hemisphere damage (LHDP). However, reported results differ with respect to the characteristics and severities of these impairments AIMS: We conducted a systematic literature review focusing on production and comprehension of linguistic prosody at the prosody-syntax interface (i.e., phrase or sentence level) in LHDP and RHDP.

METHODS & PROCEDURES

In a systematic literature search we included: (i) empirical studies with (ii) adult RHDP and/or LHDP (iii) investigating production and/or comprehension of linguistic prosody at the (iv) phrase or sentence level (v) reporting quantitative data on prosodic measures. We excluded overview papers; studies involving participants with dysarthria, apraxia of speech, foreign accent syndrome, psychiatric diseases, and/or neurodegenerative diseases; studies focusing primarily on emotional prosody; and on lexical stress / word level; studies of which no full text was available and/or that were published in a language other than English. We searched the databases BIOSIS, MEDLINE, EMBASE, PubMed, Web of Science, CINAHL, Cochrane Library, PSYNDEX, PsycINFO and speechBITE, last searched on January 13^th 2022.We found 2,631 studies without duplicates. We identified 43 studies which were included into our systematic review. For data extraction and synthesis of results, we grouped studies by (i) modality (production vs. comprehension), (ii) function (syntactic structure vs. information structure), and (iii) by experiment task. For production studies, outcome measures were defined as the productive use of the different prosodic cues (lengthening, pause, f0, amplitude). For comprehension studies, performance measures (accuracy and reaction times) were defined as outcome measures. In accordance with the PRISMA 2020 statement (Page et al., 2021), we conducted a quality check to assess study risk of bias. Our review was pre-registered with PROSPERO (CRD42019120308).

OUTCOMES & RESULTS

Of the 43 studies reviewed, 30 studies involved RHDP (n = 309), assessing production in 15 studies and focusing on comprehension of prosody in 16 studies (one study investigated production and comprehension). LHDP (n = 438) were included in 35 studies of which 15 studied production and 21 evaluated comprehension of prosody (one study investigated production and comprehension). Despite the heterogeneity of results in the studies reviewed, our synthesis of results suggests that both LHDP and RHDP show limitations, but no complete impairment, in their production and/or comprehension of linguistic prosody. Prosodic limitations are evident in different areas of processing linguistic prosody, like syntactic disambiguation or the distinction between sentence types. There is a tendency towards more severe limitations in LHDP as compared to RHDP.

CONCLUSIONS

We only included published studies into our review and did not perform an assessment of risk of reporting bias as well as systematic certainty assessments of the outcomes. Despite these limitations, we conclude that both groups show deficits in production and comprehension of linguistic prosody, but neither LHDP nor RHDP are completely impaired in their prosodic processing. This suggests that prosody is a relevant communicative resource for LHDP and RHDP worth being addressed in speech-language-therapy.

Production and Comprehension of Prosodic Boundary Marking in Persons With Unilateral Brain Lesions

PURPOSE

Persons with unilateral brain damage in the right hemisphere (RH) or left hemisphere (LH) show limitations in processing linguistic prosody, with yet inconclusive results on their ability to process prosodically marked structural boundaries for syntactic ambiguity resolution. We aimed at systematically investigating production and comprehension of three prosodic cues (f ₀ range, final lengthening, and pause) at structural boundaries in coordinate sequences in participants with right hemisphere brain damage (RHDP) and participants with left hemisphere brain damage (LHDP).

METHOD

Twenty RHDP and 15 LHDP participated in our study. Comprehension experiment: Participants and a control group listened to coordinate name sequences with internal grouping by a prosodically marked structural boundary (grouped condition, e.g., "(Gabi und Leni) # und Nina") or without internal grouping (ungrouped condition, e.g., "Gabi und Leni und Nina") and had to identify the target condition. The strength and combinations of prosodic cues in the stimuli were manipulated. Production experiment: Participants were asked to produce coordinate sequences in the two conditions (grouped, ungrouped) in two different tasks: a Reading Aloud and a Repetition experiment. Accuracy of participants' productions was subsequently assessed in a rating study and productions were analyzed with respect to use of prosodic cues.

RESULTS

In the Comprehension experiment, RHDP and LHDP had overall lower identification accuracies than unimpaired control participants and LHDP were found to have particular problems with boundary identification when the pause cue was reduced. In production, LHDP and RHDP employed all three prosodic cues for boundary marking, but struggled to clearly mark prosodic boundaries in 28% of all productions. Both groups showed better performance in reading aloud than in repetition. LHDP relied more on using f ₀ range and pause duration to prosodically mark structural boundaries, whereas RHDP employed final lengthening more vigorously than LHDP in reading aloud.

CONCLUSIONS

We conclude that processing of linguistic prosody is affected in RHDP and LHDP, but not completely impaired. Therefore, prosody can serve as a relevant communicative resource. However, it should also be considered as a target area for assessment and treatment in both groups.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.21637505.

Distinct Contributions of Working Memory and Attentional Control to Sentence Comprehension in Noise in Persons With Stroke

Purpose Sentence comprehension deficits are common following a left hemisphere stroke and have primarily been investigated under optimal listening conditions. However, ample work in neurotypical controls indicates that background noise affects sentence comprehension and the cognitive resources it engages. The purpose of this study was to examine how background noise affects sentence comprehension poststroke using both energetic and informational maskers. We further sought to identify whether sentence comprehension in noise abilities are related to poststroke cognitive abilities, specifically working memory and/or attentional control. Method Twenty persons with chronic left hemisphere stroke completed a sentence-picture matching task where they listened to sentences presented in three types of maskers: multispeakers, broadband noise, and silence (control condition). Working memory, attentional control, and hearing thresholds were also assessed. Results A repeated-measures analysis of variance identified participants to have the greatest difficulty with the multispeakers condition, followed by broadband noise and then silence. Regression analyses, after controlling for age and hearing ability, identified working memory as a significant predictor of listening engagement (i.e., mean reaction time) in broadband noise and multispeakers and attentional control as a significant predictor of informational masking effects (computed as a reaction time difference score where broadband noise is subtracted from multispeakers). Conclusions The results from this study indicate that background noise impacts sentence comprehension abilities poststroke and that these difficulties may arise due to deficits in the cognitive resources supporting sentence comprehension and not other factors such as age or hearing. These findings also highlight a relationship between working memory abilities and sentence comprehension in background noise. We further suggest that attentional control abilities contribute to sentence comprehension by supporting the additional demands associated with informational masking. Supplemental Material https://doi.org/10.23641/asha.14984511.

Abnormal singing can identify patients with right hemisphere cortical strokes at risk for impaired prosody

Despite lacking aphasia seen with left hemisphere (LH) infarcts involving the middle cerebral artery territory, right hemisphere (RH) strokes can result in significant difficulties in affective prosody. These impairments may be more difficult to identify but lead to significant communication problems.We determine if evaluation of singing can accurately identify stroke patients with cortical RH infarcts at risk for prosodic impairment who may benefit from rehabilitation.A prospective cohort of 36 patients evaluated with acute ischemic stroke was recruited. Participants underwent an experimental battery evaluating their singing, prosody comprehension, and prosody production. Singing samples were rated by 2 independent reviewers as subjectively "normal" or "abnormal," and analyzed for properties of the fundamental frequency. Relationships between infarct location, singing, and prosody performance were evaluated using t tests and chi-squared analysis.Eighty percent of participants with LH cortical strokes were unable to successfully complete any of the tasks due to severe aphasia. For the remainder, singing ratings corresponded to stroke location for 68% of patients. RH cortical strokes demonstrated a lower mean fundamental frequency while singing than those with subcortical infarcts (176.8 vs 130.4, P = 0.02). They also made more errors on tasks of prosody comprehension (28.6 vs 16.0, P < 0.001) and production (40.4 vs 18.4, P < 0.001).Patients with RH cortical infarcts are more likely to exhibit impaired prosody comprehension and production and demonstrate the poor variation of tone when singing compared to patients with subcortical infarcts. A simple singing screen is able to successfully identify patients with cortical lesions and potential prosodic deficits.

The Role of the Dorsolateral Prefrontal Cortex for Speech and Language Processing

This review article summarizes various functions of the dorsolateral prefrontal cortex (DLPFC) that are related to language processing. To this end, its connectivity with the left-dominant perisylvian language network was considered, as well as its interaction with other functional networks that, directly or indirectly, contribute to language processing. Language-related functions of the DLPFC comprise various aspects of pragmatic processing such as discourse management, integration of prosody, interpretation of nonliteral meanings, inference making, ambiguity resolution, and error repair. Neurophysiologically, the DLPFC seems to be a key region for implementing functional connectivity between the language network and other functional networks, including cortico-cortical as well as subcortical circuits. Considering clinical aspects, damage to the DLPFC causes psychiatric communication deficits rather than typical aphasic language syndromes. Although the number of well-controlled studies on DLPFC language functions is still limited, the DLPFC might be an important target region for the treatment of pragmatic language disorders.

Auditory attention following a left hemisphere stroke: comparisons of alerting, orienting, and executive control performance using an auditory Attention Network Test

INTRODUCTION

Auditory attention is a critical foundation for successful language comprehension, yet is rarely studied in individuals with acquired language disorders.

METHODS

We used an auditory version of the well-studied Attention Network Test to study alerting, orienting, and executive control in 28 persons with chronic stroke (PWS). We further sought to characterize the neurobiology of each auditory attention measure in our sample using exploratory lesion-symptom mapping analyses.

RESULTS

PWS exhibited the expected executive control effect (i.e., decreased accuracy for incongruent compared to congruent trials), but their alerting and orienting attention were disrupted. PWS did not exhibit an alerting effect and they were actually distracted by the auditory spatial orienting cue compared to the control cue. Lesion-symptom mapping indicated that poorer alerting and orienting were associated with damage to the left retrolenticular part of the internal capsule (adjacent to the thalamus) and left posterior middle frontal gyrus (overlapping with the frontal eye fields), respectively.

DISCUSSION

The behavioral findings correspond to our previous work investigating alerting and spatial orienting attention in persons with aphasia in the visual modality and suggest that auditory alerting and spatial orienting attention may be impaired in PWS due to stroke lesions damaging multi-modal attention resources.

Assessment of alerting, orienting, and executive control in persons with aphasia using the Attention Network Test

BACKGROUND

Attention deficits frequently accompany language impairments in aphasia. Most research on attention in aphasia focuses on selective attention measured by executive control tasks such as the color-word Stroop or Erickson flanker. This is despite ample evidence in neurotypical adults indicating the existence of multiple, distinct attention subtypes. Thus, there is a disconnect between the documented attention impairments in persons with aphasia (PWA) and the literature in neurotypical adults indicating that multiple attention components independently modulate an individual's interactions with the world.

AIMS

This study aimed to use the well-studied Attention Network Test (ANT) to quantify three subtypes of attention (alerting, orienting, and executive control) in PWA and matched controls. It was hypothesized that significant effects of alerting, orienting, and executive control would be observed in both groups, however, the effects would be reduced in PWA compared to the neurotypical controls. It was additionally expected that alerting, orienting, and executive control would not be correlated with one another in either group.

METHODS & PROCEDURES

Twenty-two PWA along with 20 age, gender, and education matched controls completed the ANT. Briefly, the ANT consists of a cued-flanker task where the cues provide information about when and where the flanker executive control task will be presented. The combination of cues and flanker targets embedded within the ANT provides measures of alerting, orienting, and executive control. Participants are expected to respond faster and more accurately to the flanker task when cued as to when and where the task will be presented.

OUTCOMES & RESULTS

In line with previous work, the control group demonstrated significant effects of alerting, orienting, and executive control. However, we only find significant orienting and executive control effects in the aphasia group. Between-group differences were only identified within orienting attention: the control group benefitted more from the orienting cue than the aphasia group. Additionally, alerting, orienting, and executive control were not correlated in the control group, yet, a relationship between orienting and executive control was observed in the aphasia group.

CONCLUSIONS

Overall, our findings demonstrate that attention differs between PWA and controls, and that the ANT may provide a more complete picture of attention in aphasia; this may be particularly important when characterizing the relationship between attention and language in aphasia.