Investigating silent pauses in connected speech: integrating linguistic, neuropsychological, and neuroanatomical perspectives across narrative tasks in post-stroke aphasia

Introduction

Silent pauses are regarded as integral components of the temporal organization of speech. However, it has also been hypothesized that they serve as markers for internal cognitive processes, including word access, monitoring, planning, and memory functions. Although existing evidence across various pathological populations underscores the importance of investigating silent pauses' characteristics, particularly in terms of frequency and duration, there is a scarcity of data within the domain of post-stroke aphasia.

Methods

The primary objective of the present study is to scrutinize the frequency and duration of silent pauses in two distinct narrative tasks within a cohort of 32 patients with chronic post-stroke aphasia, in comparison with a control group of healthy speakers. Subsequently, we investigate potential correlation patterns between silent pause measures, i.e., frequency and duration, across the two narrative tasks within the patient group, their performance in neuropsychological assessments, and lesion data.

Results

Our findings showed that patients exhibited a higher frequency of longer-duration pauses in both narrative tasks compared to healthy speakers. Furthermore, within-group comparisons revealed that patients tended to pause more frequently and for longer durations in the picture description task, while healthy participants exhibited the opposite trend. With regard to our second research question, a marginally significant interaction emerged between performance in semantic verbal fluency and the narrative task, in relation to the location of silent pauses-whether between or within clauses-predicting the duration of silent pauses in the patient group. However, no significant results were observed for the frequency of silent pauses. Lastly, our study identified that the duration of silent pauses could be predicted by distinct Regions of Interest (ROIs) in spared tissue within the left hemisphere, as a function of the narrative task.

Discussion

Overall, this study follows an integrative approach of linguistic, neuropsychological and neuroanatomical data to define silent pauses in connected speech, and illustrates interrelations between cognitive components, temporal aspects of speech, and anatomical indices, while it further highlights the importance of studying connected speech indices using different narrative tasks.

Reliability of the picture description task of the Western Aphasia Battery - revised in Laurentian French persons without brain injury

Objective: Limited normative data (including psychometric properties) are currently available on discourse tasks in non-dominant languages such as Laurentian (Quebec) French. The lack of linguistic and cultural adaptation has been identified as a barrier to discourse assessment. The main aim of this study is to document inter-rater and test-retest reliability properties of the picnic scene of the Western Aphasia Battery - Revised (WAB-R), including the cultural adaptation of an information content unit (ICU) list, and provide a normative reference for persons without brain injury (PWBI). Method: To do so, we also aimed to adapt an ICU checklist culturally and linguistically for Laurentian French speakers. Discourse samples were collected from 66 PWBI using the picture description task of the WAB-R. The ICU list was first adapted into Laurentian French. Then, ICUs and thematic units (TUs) were extracted manually, and microstructural variables were extracted using CLAN. Inter-rater reliability and test-retest reliability were determined. Results: Excellent inter-rater reliability was obtained for ICUs and TUs, as well as for all microstructural variables, except for mean length of utterance, which was found to be good. Conversely, test-retest reliability ranged from poor to moderate for all variables. Conclusion: The present study provides a validated ICU checklist for clinicians and researchers working with Laurentian French speakers when assessing discourse with the picnic scene of the WAB-R. It also addresses the gap in available psychometric data regarding inter-rater and test-retest reliability in PWBI.

Exploring high-technology augmentative and alternative communication interfaces: the effect of age and technology experience

PURPOSE

Many people with aphasia have inadequate language skills for functional communication thereby necessitating well-designed augmentative and alternative communication (AAC) interfaces. Using both a grid and a VSD interface with single word hotspots by neurologically healthy adults, across ages and with different technology experiences, this study examines the utility of these interfaces prior to investigating their use with people with aphasia in future studies.

METHOD

Participants include 18 young adults, 24 older adults with technology experience, and 20 older adults with limited technology experience. The older adult groups were matched for mean age and for sex. Participants described pictures with each interface, and performance was measured based on four dependent variables: (a) the total number of correct information units (CIUs), (b) the percentage of CIUs, (c) CIUs per minute, and (d) preferred interface.

RESULTS

There was a significant difference between older adults and the young adult group for the total number of CIUs (p < 0.001) and CIUs per minute (p < 0.001). Despite the changes in technology experience between the two older groups, there was no significant difference in performance. Additionally, there was no significant difference in performance across the two interfaces in any of the groups.

CONCLUSION

Findings suggest age does impact performance on AAC. However, the difference in technology experience in older adult groups did not affect performance. Furthermore, both interfaces used in the current study were equally beneficial when describing pictures by healthy adults. Implications for RehabilitationAugmentative and alternative communication (AAC) systems involve various interface designs. Consequently, the comparative utility of these interfaces must be examined across populations and communicative functions.Advancement in technology has given rise to numerous high-tech AAC interface designs. However, older adults with acquired language difficulties whose technology experience is limited may become reluctant to use high-tech AAC. Hence, the  influence of technology experience on high-tech AAC performance should be investigated.Prior to examining interfaces with individuals with acquired language difficulties, the current study examined the use of a) grid display and b) visual scene display (VSD) with single word hotspots, by healthy adults of different ages and technology experiences.The study revealed that older adults with limited technology experience were equally competent in using high-tech AAC interfaces, as those with technology experience. Hence, an individual's technology experience should not be considered a deterrent to using high-tech AAC interfaces.Additionally, the study found no differences in performance between the two interfaces, making it essential to consider user's personal preference when adopting AAC interface designs.

Impaired discourse content in aphasia is associated with frontal white matter damage

Aphasia is a common consequence of stroke with severe impacts on employability, social interactions and quality of life. Producing discourse-relevant information in a real-world setting is the most important aspect of recovery because it is critical to successful communication. This study sought to identify the lesion correlates of impaired production of relevant information in spoken discourse in a large, unselected sample of participants with post-stroke aphasia. Spoken discourse (n = 80) and structural brain scans (n = 66) from participants with aphasia following left hemisphere stroke were analysed. Each participant provided 10 samples of spoken discourse elicited in three different genres, and 'correct information unit' analysis was used to quantify the informativeness of speech samples. The lesion correlates were identified using multivariate lesion-symptom mapping, voxel-wise disconnection and tract-wise analyses. Amount and speed of relevant information were highly correlated across different genres and with total lesion size. The analyses of lesion correlates converged on the same pattern: impaired production of relevant information was associated with damage to anterior dorsal white matter pathways, specifically the arcuate fasciculus, frontal aslant tract and superior longitudinal fasciculus. Damage to these pathways may be a useful biomarker for impaired informative spoken discourse and informs development of neurorehabilitation strategies.

EXPRESS: Representation of others' synchronous and asynchronous sentences interferes with sentence production

In dialogue, people represent each other's utterances in order to take turns and communicate successfully. In previous work [Gambi, C., Van de Cavey, J., & Pickering, M. J. (2015). Interference in joint picture naming. Journal of Experimental Psychology: Learning, Memory, and Cognition, 41(1), 1-21.], speakers who were naming single pictures or picture pairs represented whether another speaker was engaged in the same task (versus a different or no task) concurrently, but did not represent in detail the content of the other speaker's utterance. Here, we investigate co-representation of whole sentences. In three experiments, pairs of speakers imagined each other producing active or passive descriptions of transitive events. Speakers took longer to begin speaking when they believed their partner was also preparing to speak, compared to when they did not. Interference occurred when speakers believed their partners were preparing to speak at the same time as them (synchronous production and co-representation; Experiment 1), and also when speakers believed that their partner would speak only after them (asynchronous production and co-representation; Experiments 2a and 2b). However, interference was generally no greater when speakers believed their partner was preparing a different compared to a similar utterance, providing no consistent evidence that speakers represented what their partners were preparing to say. Taken together, these findings indicate that speakers can represent another's intention to speak even as they are themselves preparing to speak, but that such representation tends to lack detail.

Amyloid beta associations with connected speech in cognitively unimpaired adults

INTRODUCTION

Connected speech and language (CSL) decline has been associated with early cognitive decline, but associations between CSL and Alzheimer's disease (AD) biomarkers remain a gap in the literature. Our goal was to examine associations with amyloid beta (Aβ) and longitudinal CSL trajectories in cognitively unimpaired adults at increased AD risk.

METHODS

Using data from the Wisconsin Registry for Alzheimer's Prevention, CSL measures were automatically extracted from digitally recorded picture descriptions. Positron emission tomography determined Aβ status. Linear mixed effects models assessed the interaction between age and Aβ on CSL trajectories.

RESULTS

Participants who were Aβ positive experienced more rapid decline on specific word content, when controlling for age, sex, and literacy. There were no differences between groups in lexical diversity measures over time.

DISCUSSION

These results indicate that declines in connected speech may be related to preclinical AD. CSL may be a promising, inexpensive, and easy-to-collect digital cognitive marker for AD studies.

Language Impairment in Alzheimer's Disease-Robust and Explainable Evidence for AD-Related Deterioration of Spontaneous Speech Through Multilingual Machine Learning

Alzheimer's disease (AD) is a pervasive neurodegenerative disease that affects millions worldwide and is most prominently associated with broad cognitive decline, including language impairment. Picture description tasks are routinely used to monitor language impairment in AD. Due to the high amount of manual resources needed for an in-depth analysis of thereby-produced spontaneous speech, advanced natural language processing (NLP) combined with machine learning (ML) represents a promising opportunity. In this applied research field though, NLP and ML methodology do not necessarily ensure robust clinically actionable insights into cognitive language impairment in AD and additional precautions must be taken to ensure clinical-validity and generalizability of results. In this study, we add generalizability through multilingual feature statistics to computational approaches for the detection of language impairment in AD. We include 154 participants (78 healthy subjects, 76 patients with AD) from two different languages (106 English speaking and 47 French speaking). Each participant completed a picture description task, in addition to a battery of neuropsychological tests. Each response was recorded and manually transcribed. From this, task-specific, semantic, syntactic and paralinguistic features are extracted using NLP resources. Using inferential statistics, we determined language features, excluding task specific features, that are significant in both languages and therefore represent "generalizable" signs for cognitive language impairment in AD. In a second step, we evaluated all features as well as the generalizable ones for English, French and both languages in a binary discrimination ML scenario (AD vs. healthy) using a variety of classifiers. The generalizable language feature set outperforms the all language feature set in English, French and the multilingual scenarios. Semantic features are the most generalizable while paralinguistic features show no overlap between languages. The multilingual model shows an equal distribution of error in both English and French. By leveraging multilingual statistics combined with a theory-driven approach, we identify AD-related language impairment that generalizes beyond a single corpus or language to model language impairment as a clinically-relevant cognitive symptom. We find a primary impairment in semantics in addition to mild syntactic impairment, possibly confounded by additional impaired cognitive functions.

Word-finding in confrontation naming and picture descriptions produced by individuals with early post-stroke aphasia

OBJECTIVE

The present study aims to assess the relationship between quantitative measures of connected speech production and performance in confrontation naming in early post-stroke aphasia (8-14 days post-stroke). Method: We collected connected speech samples elicited by a picture description task and administered a confrontation naming task to 20 individuals with early post-stroke aphasia and 20 healthy controls. Transcriptions were made in compliance with the CHAT format guidelines. Several micro- (i.e. duration, total number of words, words per minute, mean length of utterances, ratio of open- to closed-class words and noun-to-verb ratio, VOC-D, repetitions, self-corrections, and phonological and semantic errors) and macrolinguistic (i.e. informativeness and efficiency) measures were extracted. Results: We provide evidence for the presence of impairments in an array of micro- and macrolinguistic measures of speech in individuals with early post-stroke aphasia. We show that in the patient group, confrontation naming abilities most strongly relate to informativeness in a picture description task. Conclusion: Our findings contribute to a better understanding of the relationship between performance in confrontation naming and in connected speech production in the first days after stroke onset and also suggest that discourse analysis may provide unique, possibly more complex information.

Main concepts for two picture description tasks: An addition to

BACKGROUND

Proposition analysis of the discourse of persons with aphasia has a long history, yielding important advancements in our understanding of communication impairments in this population. Recently, discourse measures have been considered primary outcome measures, and multiple calls have been made for improved psychometric properties of discourse measures.

AIMS

To advance the use of discourse analysis in persons with aphasia by providing Main Concept Analysis checklists and descriptive statistics for healthy control performance on the analysis for the Cat in the Tree and Refused Umbrella narrative tasks utilized in the AphasiaBank database protocol.

METHODS & PROCEDURES

Ninety-two control transcripts, stratified into four age groups (20-39 years; 40-59; 60-79; 80+), were downloaded from the AphasiaBank database. Relevant concepts were identified, and those spoken by at least one-third of the control sample were considered to be a main concept. A multi-level coding system was used to determine the accuracy and completeness of the main concepts produced by control speakers.

OUTCOMES & RESULTS

Main concept checklists for two discourse tasks are provided. Descriptive statistics are reported and examined to assist readers with evaluation of the normative data.

CONCLUSIONS

These checklists provide clinicians and researchers with a tool to reliably assess the discourse of persons with aphasia. They also help address the gap in available psychometric data with which to compare persons with aphasia to healthy controls.

Connected speech and language in mild cognitive impairment and Alzheimer's disease: A review of picture description tasks

INTRODUCTION

The neuropsychological profile of people with mild cognitive impairment (MCI) and Alzheimer's disease (AD) dementia includes a history of decline in memory and other cognitive domains, including language. While language impairments have been well described in AD dementia, language features of MCI are less well understood. Connected speech and language analysis is the study of an individual's spoken discourse, usually elicited by a target stimulus, the results of which can facilitate understanding of how language deficits typical of MCI and AD dementia manifest in everyday communication. Among discourse genres, picture description is a constrained task that relies less on episodic memory and more on semantic knowledge and retrieval, within the cognitive demands of a communication context. Understanding the breadth of evidence across the continuum of cognitive decline will help to elucidate the areas of strength and need in terms of using this method as an evaluative tool for both cognitive changes and everyday functional communication.

METHOD

We performed an extensive literature search of peer-reviewed journal articles that focused on the use of picture description tasks for evaluating language in persons with MCI or AD dementia. We selected articles based on inclusion and exclusion criteria and described the measures assessed, the psychometric properties that were reported, the findings, and the limitations of the included studies.

RESULTS

36 studies were selected and reviewed. Across all 36 studies, there were 1, 127 patients with AD dementia and 274 with MCI or early cognitive decline. Multiple measures were examined, including those describing semantic content, syntactic complexity, speech fluency, vocal parameters, and pragmatic language. Discriminant validity widely reported and distinct differences in language were observable between adults with dementia and controls; fewer studies were able to distinguish language differences between typically aging adults and those with MCI.

DISCUSSION

Our review shows that picture description tasks are useful tools for detecting differences in a wide variety of language and communicative measures. Future research should expand knowledge about subtle changes to language in preclinical AD and Mild Cognitive Impairment (MCI) which may improve the utility of this method as a clinically meaningful screening tool.

Selective effects of specificity inductions on episodic details: evidence for an event construction account

Prior research has suggested that an episodic specificity induction - brief training in recollecting the details of a past event - affects downstream performance on remembering past and imagining future events, solving problems, and thinking creatively. We have hypothesised that a process common to these tasks that the induction may target is event construction - assembling and maintaining a mental scenario filled with details related to settings, people, and actions. We test this hypothesis by having participants receive a memory specificity induction, imagination specificity induction, or control induction not requiring event construction prior to memory and imagination tasks that involve event construction, and a picture description task that involves describing but not mentally constructing an event. We predicted that induction effects would be specific to episodic detail production on subsequent memory and imagination because these details assay critical elements of a constructed event. In line with an event construction account, the two specificity inductions produced significant and indistinguishable increases in the number of episodic - but not semantic - details generated during memory and imagination relative to the control. Induction did not increase detail generation on picture description. The findings provide novel evidence that event construction is a key process targeted by specificity inductions.

Declines in Connected Language Are Associated with Very Early Mild Cognitive Impairment: Results from the Wisconsin Registry for Alzheimer's Prevention

Changes to everyday spoken language ("connected language") are evident in persons with AD dementia, yet little is known about when these changes are first detectable on the continuum of cognitive decline. The aim of this study was to determine if participants with very early, subclinical memory declines were also showing declines in connected language. We analyzed connected language samples obtained from a simple picture description task at two time points in 264 participants from the Wisconsin Registry for Alzheimer's Prevention (WRAP). In parallel, participants were classified as either "Cognitively Healthy" or "Early Mild Cognitive Impairment" based on longitudinal neuropsychological test performance. Linear mixed effects models were used to analyze language parameters that were extracted from the connected language samples using automated feature extraction. Participants with eMCI status declined faster in features of speech fluency and semantic content than those who were cognitively stable. Measures of lexical diversity and grammatical complexity were not associated with eMCI status in this group. These findings provide novel insights about the relationship between cognitive decline and everyday language, using a quick, inexpensive, and performance-based method.

How scenes containing visual errors affect speech fluency in young and older adults

We compared young and older adults' speech during an error detection task, with some pictures containing visual errors and anomalies and other pictures error-free. We analyzed three disfluency types: mid-phrase speech fillers (e.g., It's a little, um, girl), repetitions (e.g., He's trying to catch the- the birds), and repairs (e.g., She- you can see her legs). Older adults produced more mid-phrase fillers than young adults only when describing pictures containing errors. These often reflect word retrieval problems and represent clear disruptions to fluency, so this interaction indicates that the need to form and maintain representations of novel information can specifically compromise older adults' speech fluency. Overall, older adults produced more repetitions and repairs than young adults, regardless of picture type, indicating general age-related increases in these disfluencies. The obtained patterns are discussed in the context of the Transmission Deficit Hypothesis and other approaches to age-related changes in speech fluency.

Connected Speech in Neurodegenerative Language Disorders: A Review

Language assessment has a crucial role in the clinical diagnosis of several neurodegenerative diseases. The analysis of extended speech production is a precious source of information encompassing the phonetic, phonological, lexico-semantic, morpho-syntactic, and pragmatic levels of language organization. The knowledge about the distinctive linguistic variables identifying language deficits associated to different neurodegenerative diseases has progressively improved in the last years. However, the heterogeneity of such variables and of the way they are measured and classified limits any generalization and makes the comparison among studies difficult. Here we present an exhaustive review of the studies focusing on the linguistic variables derived from the analysis of connected speech samples, with the aim of characterizing the language disorders of the most prevalent neurodegenerative diseases, including primary progressive aphasia, Alzheimer's disease, movement disorders, and amyotrophic lateral sclerosis. A total of 61 studies have been included, considering only those reporting group analysis and comparisons with a group of healthy persons. This review first analyzes the differences in the tasks used to elicit connected speech, namely picture description, story narration, and interview, considering the possible different contributions to the assessment of different linguistic domains. This is followed by an analysis of the terminologies and of the methods of measurements of the variables, indicating the need for harmonization and standardization. The final section reviews the linguistic domains affected by each different neurodegenerative disease, indicating the variables most consistently impaired at each level and suggesting the key variables helping in the differential diagnosis among diseases. While a large amount of valuable information is already available, the review highlights the need of further work, including the development of automated methods, to take advantage of the richness of connected speech analysis for both research and clinical purposes.

Delayed Stimulus-Specific Improvements in Discourse Following Anomia Treatment Using an Intentional Gesture

Purpose: In this study, the authors assessed how the addition of intentional left-hand gestures to an intensive treatment for anomia affects 2 types of discourse: picture description and responses to open-ended questions.Method: Fourteen people with aphasia completed treatment for anomia comprising 30 treatment sessions over 3 weeks.Seven subjects also incorporated intentional left-hand gestures into each treatment trial.Results: Both groups demonstrated significant changes in trained items and improved naming of untrained items but no change in Western Aphasia Battery—Aphasia Quotient(WAB–AQ; Kertesz, 1982) scores. Changes in discourse were limited to the 3-month follow-up assessment. Several discourse measures showed significant improvements in the picture description task and declines during question responses. Additionally, the gesture group produced more words at each assessment, whereas the no gesture group produced fewer words at each assessment. These patterns led to improvements in picture descriptions and minimal declines in question responses in the gesture group. In contrast, the no gesture group showed minimal improvements in picture descriptions and production declines in question responses relative to pretreatment levels.Conclusion: The intensive treatment protocol is a successful method for improving picture naming even of untrained items.Further, the authors conclude that the intentional left-hand gesture contributed significantly to the generalization of treatment to discourse.