Brain functional connectivity alterations of Wernicke's area in individuals with autism spectrum conditions in multi-frequency bands: A mega-analysis

Characterized by severe deficits in communication, most individuals with autism spectrum conditions (ASC) experience significant language dysfunctions, thereby impacting their overall quality of life. Wernicke's area, a classical and traditional brain region associated with language processing, plays a substantial role in the manifestation of language impairments. The current study carried out a mega-analysis to attain a comprehensive understanding of the neural mechanisms underpinning ASC, particularly in the context of language processing. The study employed the Autism Brain Image Data Exchange (ABIDE) dataset, which encompasses data from 443 typically developing (TD) individuals and 362 individuals with ASC. The objective was to detect abnormal functional connectivity (FC) between Wernicke's area and other language-related functional regions, and identify frequency-specific altered FC using Wernicke's area as the seed region in ASC. The findings revealed that increased FC in individuals with ASC has frequency-specific characteristics. Further, in the conventional frequency band (0.01-0.08 Hz), individuals with ASC exhibited increased FC between Wernicke's area and the right thalamus compared with TD individuals. In the slow-5 frequency band (0.01-0.027 Hz), increased FC values were observed in the left cerebellum Crus II and the right lenticular nucleus, pallidum. These results provide novel insights into the potential neural mechanisms underlying communication deficits in ASC from the perspective of language impairments.

Performance of machine learning algorithms for dementia assessment: impacts of language tasks, recording media, and modalities

OBJECTIVES

Automatic speech and language assessment methods (SLAMs) can help clinicians assess speech and language impairments associated with dementia in older adults. The basis of any automatic SLAMs is a machine learning (ML) classifier that is trained on participants' speech and language. However, language tasks, recording media, and modalities impact the performance of ML classifiers. Thus, this research has focused on evaluating the effects of the above-mentioned factors on the performance of ML classifiers that can be used for dementia assessment.

METHODOLOGY

Our methodology includes the following steps: (1) Collecting speech and language datasets from patients and healthy controls; (2) Using feature engineering methods which include feature extraction methods to extract linguistic and acoustic features and feature selection methods to select most informative features; (3) Training different ML classifiers; and (4) Evaluating the performance of ML classifiers to investigate the impacts of language tasks, recording media, and modalities on dementia assessment.

RESULTS

Our results show that (1) the ML classifiers trained with the picture description language task perform better than the classifiers trained with the story recall language task; (2) the data obtained from phone-based recordings improves the performance of ML classifiers compared to data obtained from web-based recordings; and (3) the ML classifiers trained with acoustic features perform better than the classifiers trained with linguistic features.

CONCLUSION

This research demonstrates that we can improve the performance of automatic SLAMs as dementia assessment methods if we: (1) Use the picture description task to obtain participants' speech; (2) Collect participants' voices via phone-based recordings; and (3) Train ML classifiers using only acoustic features. Our proposed methodology will help future researchers to investigate the impacts of different factors on the performance of ML classifiers for assessing dementia.

Neuro-Clinical Signatures of Language Impairments after Acute Stroke: A VBQ Analysis of Quantitative Native CT Scans

OBJECTIVES

Ischemic stroke affects language production and/or comprehension and leads to devastating long-term consequences for patients and their families. Previous studies have shown that neuroimaging can increase our knowledge of the basic mechanisms of language recovery. Currently, models for predicting patients' outcomes have limited use in the clinic for the evaluation and optimization of rehabilitative strategies mostly because that are often based on high-resolution magnetic resonance imaging (MRI) data, which are not always possible to carry out in the clinical routine. Here, we investigate the use of Voxel-Based Morphometry (VBM), multivariate modelling and native Computed Tomography (nCT) scans routinely acquired in the acute stage of stroke for identifying biological signatures that explicate the relationships between brain anatomy and types of impairments.

METHODS

80 stroke patients and 30 controls were included. nCT-scans were acquired in the acute ischemia stage and bedside clinical assessment from board-certified neurologist based on the NIH stroke scale. We use a multivariate Principal Component Analyses (PCA) to identify the brain signatures group the patients according to the presence or absence of impairment and identify the association between local Grey Matter (GM) and White Matter (WM) nCT values with the presence or absence of the impairment.

RESULTS

Individual patient's nCT scans were compared to a group of controls' with no radiological signs of stroke to provide an automated delineation of the lesion. Consistently across the whole group the regions that presented significant difference GM and WM values overlap with known areas that support language processing.

CONCLUSION

In summary, the method applied to nCT scans performed in the acute stage of stroke provided robust and accurate information about brain lesions' location and size, as well as quantitative values. We found that nCT and VBQ analyses are effective for identifying neural signatures of concomitant language impairments at the individual level, and neuroanatomical maps of aphasia at the population level. The signatures explicate the neurophysiological mechanisms underlying aetiology of the stroke. Ultimately, similar analyses with larger cohorts could lead to a more integrated multimodal model of behaviour and brain anatomy in the early stage of ischemic stroke.

Neuro-Clinical Signatures of Language Impairments: A Theoretical Framework for Function-to-structure Mapping in Clinics

In the past decades, neuroscientists and clinicians have collected a considerable amount of data and drastically increased our knowledge about the mapping of language in the brain. The emerging picture from the accumulated knowledge is that there are complex and combinatorial relationships between language functions and anatomical brain regions. Understanding the underlying principles of this complex mapping is of paramount importance for the identification of the brain signature of language and Neuro-Clinical signatures that explain language impairments and predict language recovery after stroke. We review recent attempts to addresses this question of language-brain mapping. We introduce the different concepts of mapping (from diffeomorphic one-to-one mapping to many-to-many mapping). We build those different forms of mapping to derive a theoretical framework where the current principles of brain architectures including redundancy, degeneracy, pluri-potentiality and bow-tie network are described.

Acquired epileptiform aphasia: 44 years after diagnosis

We report a case of a 48-year-old woman who was diagnosed with Landau-Kleffner syndrome (LKS) at the age of 4 and reassessed by the same neurologist four decades later. While her seizures abated by the time she was 12 years old, she was left with chronic aphasia, despite receiving optimal care. Although she graduated from high school, started her own family, and was gainfully employed, she was vulnerable in situations that required clear communication. This case reflects successful management of an otherwise debilitating condition and reminds us of the vulnerability of adults with LKS and their need for a life-long support.

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Acquired epileptiform aphasia, and LKS as its variant, has lifelong consequences.

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Even those who recover relatively well from LKS face lifelong social, communication and economic challenges.

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Educational and psychological support with effective social restructuring may be necessary for adults with LKS.

Testing the therapeutic effects of transcranial direct current stimulation (tDCS) in semantic dementia: a double blind, sham controlled, randomized clinical trial

BACKGROUND

Semantic dementia is a neurodegenerative disease that primarily affects the left anterior temporal lobe, resulting in a gradual loss of conceptual knowledge. There is currently no validated treatment. Transcranial stimulation has provided evidence for long-lasting language effects presumably linked to stimulation-induced neuroplasticity in post-stroke aphasia. However, studies evaluating its effects in neurodegenerative diseases such as semantic dementia are still rare and evidence from double-blind, prospective, therapeutic trials is required.

OBJECTIVE

The primary objective of the present clinical trial (STIM-SD) is to evaluate the therapeutic efficacy of a multiday transcranial direct current stimulation (tDCS) regime on language impairment in patients with semantic dementia. The study also explores the time course of potential tDCS-driven improvements and uses imaging biomarkers that could reflect stimulation-induced neuroplasticity.

METHODS

This is a double-blind, sham-controlled, randomized study using transcranial Direct Current Stimulation (tDCS) applied daily for 10 days, and language/semantic and imaging assessments at four time points: baseline, 3 days, 2 weeks and 4 months after 10 stimulation sessions. Language/semantic assessments will be carried out at these same 4 time points. Fluorodeoxyglucose positron emission tomography (FDG-PET), resting-state functional magnetic resonance imaging (rs-fMRI), T1-weighted images and white matter diffusion tensor imaging (DTI) will be applied at baseline and at the 2-week time point. According to the principle of inter-hemispheric inhibition between left (language-related) and right homotopic regions we will use two stimulation modalities - left-anodal and right-cathodal tDCS over the anterior temporal lobes. Accordingly, the patient population (n = 60) will be subdivided into three subgroups: left-anodal tDCS (n = 20), right-cathodal tDCS (n = 20) and sham tDCS (n = 20). The stimulation will be sustained for 20 min at an intensity of 1.59 mA. It will be delivered through 25cm²-round stimulation electrodes (current density of 0.06 mA/cm²) placed over the left and right anterior temporal lobes for anodal and cathodal stimulation, respectively. A group of healthy participants (n = 20) matched by age, gender and education will also be recruited and tested to provide normative values for the language/semantic tasks and imaging measures.

DISCUSSION

The aim of this study is to assess the efficacy of tDCS for language/semantic disorders in semantic dementia. A potential treatment would be easily applicable, inexpensive, and renewable when therapeutic effects disappear due to disease progression.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03481933. Registered on March 2018.

Semantic deficits in ALS related to right lingual/fusiform gyrus network involvement

BACKGROUND

The clinicopathological continuity between amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) is well known. Although ALS demonstrates language symptoms similar to FTLD, including semantic dementia, word reading impairments in ALS have not been well studied. "Jukujikun" are Kanji-written words with irregular pronunciation comparable to "exception words" and useful for detecting semantic deficits in Japan. We conducted a cross-sectional study to investigate Jukujikun reading impairments and related network changes in ALS.

METHODS

We enrolled 71 ALS patients and 69 healthy controls (HCs). Age-, sex-, and education matched HCs were recruited from another cohort study concurrently with patient registration. We examined neuropsychological factors including low frequency Jukujikun reading. We performed resting-state functional magnetic resonance imaging with voxel-based graph analysis on a subset of participants who agreed.

FINDINGS

Low frequency Jukujikun score was decreased in ALS (15·0[11·0-19·0](median[25-75 percentile])) compared with HCs (19·0[17·3-20·0]) (p < 0·001, effect size = 0·43). Fifty-two percent of ALS (N = 37) with low frequency Jukujikun score ≤ 5th percentile of HCs was classified as ALS with positive Jukujikun deficit (ALS-JD+). Compared with HCs, ALS-JD+ showed decreased degree centrality in the right lingual/fusiform gyrus, where connectivities with regions associated with word perception, semantic processing, or speech production were decreased. They also showed increased degree centrality in the left inferior/middle temporal gyrus, associated with increased connectivities involving semantic processing.

INTERPRETATION

Dysfunction of the "hub" in the right lingual/fusiform gyrus can affect semantic deficit in ALS. Considering neuropsychological symptoms as network impairments is vital for understanding various diseases. FUND: MHLW and MEXT, Japan.

Deficits in learning and memory in mice with a mutation of the candidate dyslexia susceptibility gene Dyx1c1

Dyslexia is a learning disability characterized by difficulty learning to read and write. The underlying biological and genetic etiology remains poorly understood. One candidate gene, dyslexia susceptibility 1 candidate 1 (DYX1C1), has been shown to be associated with deficits in short-term memory in dyslexic populations. The purpose of the current study was to examine the behavioral phenotype of a mouse model with a homozygous conditional (forebrain) knockout of the rodent homolog Dyx1c1. Twelve Dyx1c1 conditional homozygous knockouts, 7 Dyx1c1 conditional heterozygous knockouts and 6 wild-type controls were behaviorally assessed. Mice with the homozygous Dyx1c1 knockout showed deficits on memory and learning, but not on auditory or motor tasks. These findings affirm existing evidence that DYX1C1 may play an underlying role in the development of neural systems important to learning and memory, and disruption of this function could contribute to the learning deficits seen in individuals with dyslexia.

Auditory scene analysis in school-aged children with developmental language disorders

Natural sound environments are dynamic, with overlapping acoustic input originating from simultaneously active sources. A key function of the auditory system is to integrate sensory inputs that belong together and segregate those that come from different sources. We hypothesized that this skill is impaired in individuals with phonological processing difficulties. There is considerable disagreement about whether phonological impairments observed in children with developmental language disorders can be attributed to specific linguistic deficits or to more general acoustic processing deficits. However, most tests of general auditory abilities have been conducted with a single set of sounds. We assessed the ability of school-aged children (7-15 years) to parse complex auditory non-speech input, and determined whether the presence of phonological processing impairments was associated with stream perception performance. A key finding was that children with language impairments did not show the same developmental trajectory for stream perception as typically developing children. In addition, children with language impairments required larger frequency separations between sounds to hear distinct streams compared to age-matched peers. Furthermore, phonological processing ability was a significant predictor of stream perception measures, but only in the older age groups. No such association was found in the youngest children. These results indicate that children with language impairments have difficulty parsing speech streams, or identifying individual sound events when there are competing sound sources. We conclude that language group differences may in part reflect fundamental maturational disparities in the analysis of complex auditory scenes.

Stable associations between behavioral problems and language impairments across childhood - the importance of pragmatic language problems

This study investigated language function associated with behavior problems, focusing on pragmatics. Scores on the Children's Communication Checklist Second Edition (CCC-2) in a group of 40 adolescents (12-15 years) identified with externalizing behavior problems (BP) in childhood was compared to the CCC-2 scores in a typically developing comparison group (n=37). Behavioral, emotional and language problems were assessed by the Strengths and Difficulties Questionnaire (SDQ) and 4 language items, when the children in the BP group were 7-9 years (T1). They were then assessed with the SDQ and the CCC-2 when they were 12-15 years (T2). The BP group obtained poorer scores on 9/10 subscales on the CCC-2, and 70% showed language impairments in the clinical range. Language, emotional and peer problems at T1 were strongly correlated with pragmatic language impairments in adolescence. The findings indicate that assessment of language, especially pragmatics, is vital for follow-up and treatment of behavioral problems in children and adolescents.

What do diagnostic test data tell us about differences in the profiles of children diagnosed with reading disability or language impairments?

A detailed evaluation of a child's strengths and weaknesses allows for a valid and reliable diagnosis of reading disability for the selection of optimal intervention practices. Using archival data from a clinic that specialized in the diagnosis of reading disabilities, we compared the performance of 60 children diagnosed with specific reading disability (SRD) and 31 children with language impairments and reading disability (LIRD) on measures of cognitive reasoning, verbal ability, phonological manipulation, rapid serial naming, and phonological memory. While the SRD and LIRD groups did not differ in their phonological processing, children with LIRD performed significantly below their peers with SRD on thinking ability and verbal ability measures. Rapid naming skills served as current predictors of text reading fluency and verbal ability skills served as concurrent predictors of reading comprehension in both groups. These findings highlight the need for reading diagnosticians to conduct comprehensive evaluations using a range of cognitive and language processes to ensure the most accurate and specific diagnoses of children with reading disabilities.

LEARNING OUTCOMES

Readers will be able to (a) describe general characteristics of reading disabilities, (b) differentiate features of two learning disabilities, specific reading disability and language impairments and reading disability, and (c) identify key clinical issues and approaches for identification, diagnosis, and intervention of these two diagnostic profiles.

Convergent genetic linkage and associations to language, speech and reading measures in families of probands with Specific Language Impairment

We analyzed genetic linkage and association of measures of language, speech and reading phenotypes to candidate regions in a single set of families ascertained for SLI. Sib-pair and family-based analyses were carried out for candidate gene loci for Reading Disability (RD) on chromosomes 1p36, 3p12-q13, 6p22, and 15q21, and the speech-language candidate region on 7q31 in a sample of 322 participants ascertained for Specific Language Impairment (SLI). Replication or suggestive replication of linkage was obtained in all of these regions, but the evidence suggests that the genetic influences may not be identical for the three domains. In particular, linkage analysis replicated the influence of genes on chromosome 6p for all three domains, but association analysis indicated that only one of the candidate genes for reading disability, KIAA0319, had a strong effect on language phenotypes. The findings are consistent with a multiple gene model of the comorbidity between language impairments and reading disability and have implications for neurocognitive developmental models and maturational processes.