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

IntroductionSilent 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.MethodsThe 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.ResultsOur 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.DiscussionOverall, 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

Translational Neuroscience of Aphasia and Adult Language Rehabilitation

The present chapter focuses on aphasia recovery and treatment. In the introductory section, we discuss the challenges that arise in research related to aphasia rehabilitation and recovery, as well as investigations of the language-related brain mechanisms, especially when attempting to integrate findings derived from basic neuroscience and studies with clinical populations. In the section that follows, we describe the dual model for language processing, based on evidence from humans and nonhuman primates. The next section is dedicated to the mechanisms of post-stroke recovery. In particular, we discuss prognostic factors, the mechanisms of neuroplasticity, the course of functional reorganization, and the role of the right hemisphere in aphasia recovery and rehabilitation. In the following two sections we discuss issues related to post-stroke rehabilitation focusing on aphasia, based on basic neuroscience as well as clinical research studies. In the final section we reflect on future endeavors in research related to aphasia rehabilitation, and on how intervention programs implemented in patients with aphasia could be improved, by translating findings from animal studies to human models of treatment and by following a multidisciplinary approach in an attempt to integrate findings from different research fields. © 2020, Springer Nature Switzerland AG

Evidence for Cognitive Deficits in X-Linked Charcot-Marie-Tooth Disease

Objective: X-linked Charcot-Marie-Tooth disease (CMTX) is an hereditary neuropathy caused by mutations in GJB1 coding for connexin-32, found in Schwann cells, but also expressed in oligodendrocytes. Reports have identified CNS involvement in CMTX, but no systematic study of cognitive function has been published.Methods: We assessed 24 CMTX patients (13 males; 9GJB1 mutations) with a comprehensive neuropsychological battery, including tests of memory, language, and executive functions.Results: No differences in cognitive performance were observed between males and females. A case-by-case investigation revealed selective deficits in individual patients. One subgroup (29%) demonstrated executive abnormalities; and a non-overlapping subgroup (29%), prominent reading (decoding) abnormalities.Conclusions: The present data provide evidence for cognitive deficits in CMTX. Emerging neuropsychological patterns are also discussed. © Copyright 2019 INS. Published by Cambridge University Press

Preserved visuospatial abilities in absence of the right hemisphere: A case of cerebral hemiatrophy with minimal cognitive impairment

Cerebral hemiatrophy is a rare neurological condition, usually resulting in severe and diffuse cognitive impairment. In this paper we present a 69-year old woman with notable congenital hemiatrophy with strikingly preserved cognitive functions. Cognitive assessment indicated that although her executive functions were found impaired, the remaining cognitive domains were relatively unaffected. We argue that this unexpected cognitive profile may be explained by anomalous hemispheric lateralization, driven by neuroplasticity along the developmental course. © 2022 The British Psychological Societ

Investigating Gray and White Matter Structural Substrates of Sex Differences in the Narrative Abilities of Healthy Adults

Linguistic aspects of narration have been investigated in healthy populations, in a wide variety of languages and speech genres with very different results. There is some evidence indicating that linguistic elements, such as speech rate (i.e., the measure indicating the amount of speech produced in a certain time period), mean length of utterance (MLU) (i.e., the index reflecting sentence grammatical structure), frequency of nouns and verbs, might be affected by non-linguistic factors such as sex. On the other hand, despite the existence of neuroimaging evidence of structural differences between males and females, it is yet unknown how such differences could explain between-sex disparities in linguistic abilities in natural speech contexts. To date, no study has evaluated discourse production elements in relation to sex differences and their neural correlates in terms of brain structure, a topic that could provide unique insights on the relationship between language and the brain. The aim of the present study was to determine sex differences in narrative skills in healthy adults and to investigate white and gray matter structural correlates of linguistic skills in each group. Twenty-seven male and 30 female (N = 57) right-handed, neurologically intact, monolingual Greek speakers, matched for age and years of education, participated. Narrations of a personal medical event were elicited. Linguistic elements of speech rate (words per minute), MLUs, frequency of nouns and verbs were calculated for each speech sample, by two independent raters. Structural 3D T1 images were segmented and parcellated using FreeSurfer and whole-brain between-sex differences in cortical thickness, cortical volume and surface area, were obtained. Between-group differences in white matter diffusion tensor scalars were examined via Tract-Based Spatial-Statistics and whole-brain tractography and automated tract delineation using Automated Fiber Quantification. Speech rate and noun frequency were significantly lower for men, while verb frequency was significantly higher for women, but no differences were identified for MLU. Regarding cortical measures, males demonstrated increased volume, surface area and cortical thickness in several bilateral regions, while no voxel-wise or tractography-based between-group differences in white matter metrics were observed. Regarding the relationship between sex and speech variables, hierarchical regression analyses showed that the superior/middle frontal cluster in surface area may serve as a significant predictor of speech rate variance, but only in females. We discuss several possible interpretations of how sex-related speech abilities could be represented differently in men and women in gray matter structures within the broad language network. © Copyright © 2020 Angelopoulou, Meier, Kasselimis, Pan, Tsolakopoulos, Velonakis, Karavasilis, Kelekis, Goutsos, Potagas and Kiran