Statistical analysis in Small-N Designs: using linear mixed-effects modeling for evaluating intervention effectiveness

Characterization of the plasma metabolome and lipidome in response to sleeve gastrectomy and gastric bypass surgeries reveals molecular patterns of surgical weight loss

OBJECTIVES

Bariatric surgery improves metabolic health, but the underlying mechanisms are not fully understood. We analyzed the effects of two types of bariatric surgery, sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB), on the plasma metabolome and lipidome.

METHODS

We characterized the plasma metabolome (1268 metabolites) and lipidome (953 lipids) pre-operatively and at 3 and 12 months post-operatively in 104 obese adults who were previously recruited to a prospective cohort of bariatric surgery. The metabolomic and lipidomic responses to bariatric surgery over time were analyzed using multivariable linear mixed-effects models.

RESULTS

There were significant changes in multiple metabolites and lipids, including rapid early changes in amino acid and peptide metabolites, including decreases in branched-chain amino acids (BCAAs), aromatic AAs, alanine and aspartate, and increases in glycine, serine, arginine and citrulline. There were also significant decreases in many triglyceride species, with increases in phosphatidylcholines and phosphatidylethanolamines. There were significant changes in metabolites related to energy metabolism that were apparent only after 12 months. We observed differences by bariatric surgery type in the changes in a small number of primary and secondary bile acids, including glycohyocholate and glyco-beta-muricholate.

CONCLUSIONS

Our findings highlight the comprehensive changes in metabolites and lipids that occur over the 12 months following bariatric surgery. While both SG and RYGB caused profound changes in the metabolome and lipidome, RYGB was characterized by greater increases in bile acids following surgery.

Preventing Surgeon Work-Related Musculoskeletal Disorders: A Pilot Study of the Comprehensive Operating Room Ergonomics (CORE) Program

IMPORTANCE

Work-related musculoskeletal disorders (WMSDs) among surgeons are markedly increasing. Several proposed interventions to reduce WMSDs among surgeons have been studied, but few follow an occupational therapy-oriented approach addressing biomechanical, psychophysical, and psychosocial risk factors.

OBJECTIVE

To design, implement, and assess the potential of the Comprehensive Operating Room Ergonomics (CORE) program for surgeons, a holistic evidence-based ergonomics and wellness intervention grounded in occupational therapy principles.

DESIGN

Mixed-methods pilot study with the quantitative strand embedded in the qualitative strand.

SETTING

University-affiliated hospital.

PARTICIPANTS

Six laparoscopic surgeons.

OUTCOMES AND MEASURES

CORE program outcomes were assessed using qualitative and quantitative data to indicate changes in posture, physical discomfort, sense of wellness, and operating room (OR) ergonomic performance. The Rapid Upper Limb Assessment (RULA) was used to quantify surgeons' WMSD risk level before and after intervention.

RESULTS

There were 12 baseline observations (two for each participant), and two or three post-CORE implementation observations. A statistically significant difference, F(1, 6) = 8.57, p = .03, was found between pre- and post-occupational therapy intervention RULA scores. Thematic analysis of surgeon feedback, which was overwhelmingly positive, identified five themes: postural alignment, areas of commonly reported physical pain or discomfort, setup of the OR environment, surgical ergonomics training, and ergonomics in everyday life.

CONCLUSIONS AND RELEVANCE

The CORE program effectively decreased ergonomic risk factors to optimize surgeons' occupational performance in the OR. This study demonstrates a potential solution to how occupational therapists can holistically support surgeons and health care providers who are at risk for WMSDs. Plain-Language Summary: By 2025, a surgeon shortage is expected, partly because of the increase in surgeons' work-related musculoskeletal disorders, which affect their health and job continuity. This pilot study shows that the Comprehensive Operating Room Ergonomics program effectively addresses these problems. The study also serves as a framework for occupational therapy professionals to work with health care providers on ergonomics, benefiting population health. Results suggest that this approach could enhance surgeons' work conditions, supporting the American Occupational Therapy Association's Vision 2025 to improve health and quality of life.

Finger counting to relieve working memory in children with developmental coordination disorder: Insights from behavioral and three-dimensional motion analyses

A limited number of studies have attempted to understand how motor deficits affect numerical abilities in children with developmental coordination disorder (DCD). The purpose of this study was to explore the functionality of finger-counting (FC) in children with DCD. The participants, 15 children with DCD and 15 typically developing (TD) children matched on school level and fluid reasoning abilities, were asked to use FC to solve an ordinal task with high working memory (WM) load. Behavioral measures supplemented with biomechanical measures, from three-dimensional motion analysis synchronized to a voice recording were used to assess children's performance and FC functionality (total duration, inter-finger [IF] transition, IF variance, finger/voice synchronization, and automatization of FC movements). Children with DCD were less accurate than TD children in using FC to solve ordinal problems with high WM load. This group difference could not be accounted for by poor FC skills given that FC movement turned out to be as functional in children with DCD as in their TD peers. When added to the model as a covariate, WM captured a greater proportion of intergroup variability than manual dexterity, further suggesting that their difficulties would be better accounted for by limited WM resources than by fine motor skills.

Cannabidiol (Epidyolex®) for severe behavioral manifestations in patients with tuberous sclerosis complex, mucopolysaccharidosis type III and fragile X syndrome: protocol for a series of randomized, placebo-controlled N-of-1 trials

BACKGROUND

Many rare genetic neurodevelopmental disorders (RGNDs) are characterized by intellectual disability (ID), severe cognitive and behavioral impairments, potentially diagnosed as a comorbid autism spectrum disorder or attention-deficit hyperactivity disorder. Quality of life is often impaired due to irritability, aggression and self-injurious behavior, generally refractory to standard therapies. There are indications from previous (case) studies and patient reporting that cannabidiol (CBD) may be an effective treatment for severe behavioral manifestations in RGNDs. However, clear evidence is lacking and interventional research is challenging due to the rarity as well as the heterogeneity within and between disease groups and interindividual differences in treatment response. Our objective is to examine the effectiveness of CBD on severe behavioral manifestations in three RGNDs, including Tuberous Sclerosis Complex (TSC), mucopolysaccharidosis type III (MPS III), and Fragile X syndrome (FXS), using an innovative trial design.

METHODS

We aim to conduct placebo-controlled, double-blind, block-randomized, multiple crossover N-of-1 studies with oral CBD (twice daily) in 30 patients (aged ≥ 6 years) with confirmed TSC, MPS III or FXS and severe behavioral manifestations. The treatment is oral CBD up to a maximum of 25 mg/kg/day, twice daily. The primary outcome measure is the subscale irritability of the Aberrant Behavior Checklist. Secondary outcome measures include (personalized) patient-reported outcome measures with regard to behavioral and psychiatric outcomes, disease-specific outcome measures, parental stress, seizure frequency, and adverse effects of CBD. Questionnaires will be completed and study medication will be taken at the participants' natural setting. Individual treatment effects will be determined based on summary statistics. A mixed model analysis will be applied for analyzing the effectiveness of the intervention per disorder and across disorders combining data from the individual N-of-1 trials.

DISCUSSION

These N-of-1 trials address an unmet medical need and will provide information on the effectiveness of CBD for severe behavioral manifestations in RGNDs, potentially generating generalizable knowledge at an individual-, disorder- and RGND population level.

TRIAL REGISTRATION

EudraCT: 2021-003250-23, registered 25 August 2022, https://www.clinicaltrialsregister.eu/ctr-search/trial/2021-003250-23/NL .

Developmental trajectories of spoken language comprehension and functional communication in children with cerebral palsy: A prospective cohort study

AIM

To investigate spoken language comprehension (SLC), single-word comprehension (SWC), functional communication development, and their determinants, in children with cerebral palsy.

METHOD

This was a prospective cohort study in the Netherlands spanning 2 years 6 months. The main outcomes were SLC and SWC, assessed by the Computer-Based instrument for Low motor Language Testing (C-BiLLT) and the Peabody Picture Vocabulary Test-III-NL (PPVT-III-NL) respectively; and functional communication, measured by a subscale of the Focus on the Outcomes of Communication Under Six-34 (FOCUS-34). Linear mixed models were used to determine developmental trajectories, which were compared with norm and reference data. Potential determinants, for example intellectual functions, speech production, functional communication level (classified with the Communication Function Classification System, CFCS), and functional mobility, were added to assess their effects.

RESULTS

Children with cerebral palsy (n = 188; mean age 59 months, range 17-110) were monitored for 2 years 6 months. Developmental trajectories for SLC (C-BiLLT) and SWC (PPVT-III-NL) were nonlinear; those for functional communication (FOCUS-34) were linear. Compared with norm and reference groups, significantly delayed SLC, SWC, and functional communication development were found. Determinants for SLC and SWC were intellectual functions and functional communication level (CFCS); and for functional communication development (FOCUS-34), speech production and arm-hand functioning.

INTERPRETATION

Children with cerebral palsy showed delayed SLC, SWC, and functional communication development compared with norm and reference groups. Remarkably, functional mobility was not associated with the development of SLC, SWC, or functional communication.

WHAT THIS PAPER ADDS

Children with cerebral palsy have delayed spoken language comprehension (SLC), single-word comprehension (SWC), and functional communication development, compared to norm and reference data. Determinants for SLC and SWC development are intellectual functions and functional communication level. Determinants for functional communication development are speech production and arm-hand functioning. Functional mobility is not associated with SLC, SWC, or functional communication.

Studies of Vision in Cricket-A Narrative Review

Vision is thought to play a substantial role in hitting and fielding in cricket. An understanding of which visual skills contribute during cricket play could inform future clinical training trials. This paper reviews what has been reported thus far regarding the relationship of visual skills to cricket performance and reviews the results of clinical trials in which the impact of visual skills training on cricket performance has been addressed. Fundamental or low-level visual skills, with the exception of color vision and perhaps near stereopsis and dynamic visual acuity, are similar between cricket players and the general population. Simple reaction time has been found to be shorter in cricket players in some but not all studies. While there is mixed or no evidence that the aforementioned visual skills are superior in cricket players compared to non-players, comparisons of eye and head movements and gaze tracking have revealed consistent differences between elite cricket batters and sub-elite batters. Future training studies could examine whether teaching sub-elite batters to emulate the gaze tracking patterns of elite batters is beneficial for batting. Lastly, clinical trials in which visual skills of cricket players have been trained have in many cases resulted in positive effects on visual skills, or judgments required in cricket, or cricket play. However, clinical trials with larger and more diverse groups of participants and correlations to on-field metrics and on-field performance (i.e., domain-specific assessments) are necessary before conclusions can be drawn regarding the efficacy of vision training.

Reproducibility in Small-N Treatment Research: A Tutorial Using Examples From Aphasiology

PURPOSE

Small-N studies are the dominant study design supporting evidence-based interventions in communication science and disorders, including treatments for aphasia and related disorders. However, there is little guidance for conducting reproducible analyses or selecting appropriate effect sizes in small-N studies, which has implications for scientific review, rigor, and replication. This tutorial aims to (a) demonstrate how to conduct reproducible analyses using effect sizes common to research in aphasia and related disorders and (b) provide a conceptual discussion to improve the reader's understanding of these effect sizes.

METHOD

We provide a tutorial on reproducible analyses of small-N designs in the statistical programming language R using published data from Wambaugh et al. (2017). In addition, we discuss the strengths, weaknesses, reporting requirements, and impact of experimental design decisions on effect sizes common to this body of research.

RESULTS

Reproducible code demonstrates implementation and comparison of within-case standardized mean difference, proportion of maximal gain, tau-U, and frequentist and Bayesian mixed-effects models. Data, code, and an interactive web application are available as a resource for researchers, clinicians, and students.

CONCLUSIONS

Pursuing reproducible research is key to promoting transparency in small-N treatment research. Researchers and clinicians must understand the properties of common effect size measures to make informed decisions in order to select ideal effect size measures and act as informed consumers of small-N studies. Together, a commitment to reproducibility and a keen understanding of effect sizes can improve the scientific rigor and synthesis of the evidence supporting clinical services in aphasiology and in communication sciences and disorders more broadly. Supplemental Material and Open Science Form: https://doi.org/10.23641/asha.21699476.

Rehabilitating an attrited language in a bilingual person with aphasia

Language difficulties can arise from reduced exposure to any given language (e.g. attrition) or after brain damage (e.g. aphasia). The manifestations of attrition and aphasia are often similar so differentiating between their effects on language loss and recovery is challenging. We investigated treatment effects for an English-Hebrew bilingual person with stroke-induced aphasia who had minimal contact with his Hebrew for over 14 years. We asked whether his attrited language could be rehabilitated, how effects of attrition and aphasia can be dissociated, and how such dissociation aids our understanding of the mechanisms involved in language recovery in aphasia. We administered a verb-based semantic treatment in Hebrew three times a week for six weeks (totalling 29 hours of therapy) and assessed changes in both Hebrew and English comprehension and production abilities across a variety of language tasks. Quantitative analyses demonstrated improvement in Hebrew production across language tasks, including those involving lexical retrieval processes that were trained during treatment. Improvement to English occurred in these same lexical retrieval tasks only. We interpret these results as indicating that the participant's attrited language (Hebrew) could be rehabilitated with both specific treatment and general exposure to Hebrew contributing to improvement. Furthermore, treatment effects transferred to the untreated English. Qualitative analyses indicated that an interaction among aphasia, incomplete mastery of Hebrew pre-stroke, and attrition contributed to the participant's language difficulties post-stroke. We conclude that partially shared underlying mechanisms of attrition and aphasia drive language processing and changes to it with treatment.

Treatment-induced neural reorganization in aphasia is language-domain specific: Evidence from a large-scale fMRI study

Studies investigating the effects of language intervention on the re-organization of language networks in chronic aphasia have resulted in mixed findings, likely related to-among other factors-the language function targeted during treatment. The present study investigated the effects of the type of treatment provided on neural reorganization. Seventy individuals with chronic stroke-induced aphasia, recruited from three research laboratories and meeting criteria for agrammatism, anomia or dysgraphia were assigned to either treatment (N = 51) or control (N = 19) groups. Participants in the treatment group received 12-weeks of language intervention targeting sentence comprehension/production, naming, or spelling. At baseline and post-testing, all participants performed an fMRI story comprehension task, with blocks of auditorily-presented stories alternated with blocks of reversed speech. Participants in the treatment, but not control, group significantly improved in the treated language domain. FMRI region-of-interest (ROI) analyses, conducted within regions that were either active (or homologous to active) regions in a group of 22 healthy participants on the story comprehension task, revealed a significant increase in activation from pre-to post-treatment in right-hemisphere homologues of these regions for participants in the sentence and spelling, but not naming, treatment groups, not predicted by left-hemisphere lesion size. For the sentence (but not the spelling) treatment group, activation changes within right-hemisphere homologues of language regions were positively associated with changes in measures of verb and sentence comprehension. These findings support previous research pointing to recruitment of right hemisphere tissue as a viable route for language recovery and suggest that sentence-level treatment may promote greater neuroplasticity on naturalistic, language comprehension tasks, compared to word-level treatment.

Applying adaptive distributed practice to self-managed computer-based anomia treatment: A single-case experimental design

INTRODUCTION

There is a pressing need to improve computer-based treatments for aphasia to increase access to long-term effective evidence-based interventions. The current single case design incorporated two learning principles, adaptive distributed practice and stimuli variability, to promote acquisition, retention, and generalization of words in a self-managed computer-based anomia treatment.

METHODS

Two participants with post-stroke aphasia completed a 12-week adaptive distributed practice naming intervention in a single-case experimental design. Stimuli variability was manipulated in three experimental conditions: high exemplar variability, low exemplar variability, and verbal description prompt balanced across 120 trained words. Outcomes were assessed at 1-week, 1-month, and 3-months post-treatment. Statistical comparisons and effect sizes measured in the number of words acquired, generalized, and retained were estimated using Bayesian generalized mixed-effect models.

RESULTS

Participants showed large and robust acquisition, generalization, and retention effects. Out of 120 trained words, participant 1 acquired ∼77 words (trained picture exemplars) and ∼63 generalization words (untrained picture exemplars of treated words). Similarly, participant 2 acquired ∼57 trained words and ∼48 generalization words. There was no reliable change in untrained control words for either participant. Stimuli variability did not show practically meaningful effects.

CONCLUSIONS

These case studies suggest that adaptive distributed practice is an effective method for re-training more words than typically targeted in anomia treatment research (∼47 words on average per Snell et al., 2010). Generalization across experimental conditions provided evidence for improved lexical access beyond what could be attributed to simple stimulus-response mapping. These effects were obtained using free, open-source flashcard software in a clinically feasible, asynchronous format, thereby minimizing clinical implementation barriers. Larger-scale clinical trials are required to replicate and extend these effects.

Amyloid, cerebrovascular disease, and neurodegeneration biomarkers are associated with cognitive trajectories in a racially and ethnically diverse, community-based sample

We characterized the additive contribution of cerebrovascular biomarkers to amyloid and neurodegeneration biomarkers (AV(N)) when modeling prospective, longitudinal cognitive trajectories within 3 major racial/ethnic groups. Participants (n = 172; age = 69-96 years; 62% women; 31%/49%/20% Non-Hispanic White/Non-Hispanic Black/Hispanic) from the Washington Heights-Inwood Columbia Aging Project were assessed for amyloid (Florbetaben PET), neurodegeneration (cortical thickness, hippocampal volume), and cerebrovascular disease (white matter hyperintensity (WMH), infarcts). Neuropsychological assessments occurred every 2.3 ± 0.6 years for up to 6 visits (follow-up time: 4.2 ± 3.2 years). Linear mixed-effects models were stratified by race/ethnicity groups. Higher amyloid was associated with faster memory decline in all 3 racial/ethnic groups, but was related to faster cognitive decline beyond memory in minoritized racial/ethnic groups. Higher WMH was associated with faster language, processing speed/executive function, and visuospatial ability decline in Non-Hispanic Black participants, while infarcts were associated with faster processing speed/executive function decline in Non-Hispanic White participants. Complementary information from AD, neurodegenerative, and cerebrovascular biomarkers explain decline in multiple cognitive domains, which may differ within each racial/ethnic group. Importantly, treatment strategies exist to minimize vascular contributions to cognitive decline.

Differences in implicit motor learning between adults who do and do not stutter

Implicit learning allows us to acquire complex motor skills through repeated exposure to sensory cues and repetition of motor behaviours, without awareness or effort. Implicit learning is also critical to the incremental fine-tuning of the perceptual-motor system. To understand how implicit learning and associated domain-general learning processes may contribute to motor learning differences in people who stutter, we investigated implicit finger-sequencing skills in adults who do (AWS) and do not stutter (ANS) on an Alternating Serial Reaction Time task. Our results demonstrated that, while all participants showed evidence of significant sequence-specific learning in their speed of performance, male AWS were slower and made fewer sequence-specific learning gains than their ANS counterparts. Although there were no learning gains evident in accuracy of performance, AWS performed the implicit learning task more accurately than ANS, overall. These findings may have implications for sex-based differences in the experience of developmental stuttering, for the successful acquisition of complex motor skills during development by individuals who stutter, and for the updating and automatization of speech motor plans during the therapeutic process.

Personal space regulation is affected by unilateral temporal lesions beyond the amygdala

We constantly face situations involving interactions with others that require us to automatically adjust our physical distances to avoid discomfort or anxiety. A previous case study has demonstrated that the integrity of both amygdalae is essential to regulate interpersonal distances. Despite unilateral lesion to the amygdala, as to other sectors of the medial temporal cortex, are known to also affect social behavior, their role in the regulation of interpersonal distances has never been investigated. Here, we sought to fill this gap by testing three patients with unilateral temporal lesions following surgical resections, including one patient with a lesion mainly centered on the amygdala and two with lesions to adjacent medial temporal cortex, on two versions of the stop distance paradigm (i.e. in a virtual reality environment and in a real setting). Our results showed that all three patients set shorter interpersonal distances compared to neurotypical controls. In addition, compared to controls, none of the patients adjusted such physical distances depending on facial emotional expressions, despite they preserved ability to categorize them. Finally, patients' heart rate responses differed from controls when viewing approaching faces. Our findings bring compelling evidence that unilateral lesions within the medial temporal cortex, not necessarily restricted to the amygdala, are sufficient to alter interpersonal distance, thus shedding new light on the neural circuitry regulating distance in social interactions.

PodoCount: A Robust, Fully Automated, Whole-Slide Podocyte Quantification Tool

Introduction

Podocyte depletion is a histomorphologic indicator of glomerular injury and predicts clinical outcomes. Podocyte estimation methods or podometrics are semiquantitative, technically involved, and laborious. Implementation of high-throughput podometrics in experimental and clinical workflows necessitates an automated podometrics pipeline. Recognizing that computational image analysis offers a robust approach to study cell and tissue structure, we developed and validated PodoCount (a computational tool for automated podocyte quantification in immunohistochemically labeled tissues) using a diverse data set.

Methods

Whole-slide images (WSIs) of tissues immunostained with a podocyte nuclear marker and periodic acid–Schiff counterstain were acquired. The data set consisted of murine whole kidney sections (n = 135) from 6 disease models and human kidney biopsy specimens from patients with diabetic nephropathy (DN) (n = 45). Within segmented glomeruli, podocytes were extracted and image analysis was applied to compute measures of podocyte depletion and nuclear morphometry. Computational performance evaluation and statistical testing were performed to validate podometric and associated image features. PodoCount was disbursed as an open-source, cloud-based computational tool.

Results

PodoCount produced highly accurate podocyte quantification when benchmarked against existing methods. Podocyte nuclear profiles were identified with 0.98 accuracy and segmented with 0.85 sensitivity and 0.99 specificity. Errors in podocyte count were bounded by 1 podocyte per glomerulus. Podocyte-specific image features were found to be significant predictors of disease state, proteinuria, and clinical outcome.

Conclusion

PodoCount offers high-performance podocyte quantitation in diverse murine disease models and in human kidney biopsy specimens. Resultant features offer significant correlation with associated metadata and outcome. Our cloud-based tool will provide end users with a standardized approach for automated podometrics from gigapixel-sized WSIs.

Perilesional Perfusion in Chronic Stroke-Induced Aphasia and Its Response to Behavioral Treatment Interventions

Stroke-induced alterations in cerebral blood flow (perfusion) may contribute to functional language impairments in chronic aphasia, particularly in perilesional tissue. Abnormal perfusion in this region may also serve as a biomarker for predicting functional improvements with behavioral treatment interventions. Using pseudo-continuous arterial spin labeling in magnetic resonance imaging (MRI), we examined perfusion in chronic aphasia, in perilesional rings in the left hemisphere and their right hemisphere homologues. In the left hemisphere we found a gradient pattern of decreasing perfusion closer to the lesion. The opposite pattern was found in the right hemisphere, with significantly increased perfusion close to the lesion homologue. Perfusion was also increased in the right hemisphere lesion homologue region relative to the surrounding tissue. We next examined changes in perfusion in two groups: one group who underwent MRI scanning before and after three months of a behavioral treatment intervention that led to significant language gains, and a second group who was scanned twice at a three-month interval without a treatment intervention. For both groups, there was no difference in perfusion over time in either the left or the right hemisphere. Moreover, within the treatment group pre-treatment perfusion scores did not predict treatment response; neither did pre-treatment perfusion predict post-treatment language performance. These results indicate that perfusion is chronically abnormal in both hemispheres, but chronically abnormal perfusion did not change in response to our behavioral treatment interventions, and did not predict responsiveness to language treatment.

Musical and linguistic syntactic processing in agrammatic aphasia: An ERP study

Language and music rely on complex sequences organized according to syntactic principles that are implicitly understood by enculturated listeners. Across both domains, syntactic processing involves predicting and integrating incoming elements into higher-order structures. According to the Shared Syntactic Integration Resource Hypothesis (SSIRH; Patel, 2003), musical and linguistic syntactic processing rely on shared resources for integrating incoming elements (e.g., chords, words) into unfolding sequences. One prediction of the SSIRH is that people with agrammatic aphasia (whose deficits are due to syntactic integration problems) should present with deficits in processing musical syntax. We report the first neural study to test this prediction: event-related potentials (ERPs) were measured in response to musical and linguistic syntactic violations in a group of people with agrammatic aphasia (n=7) compared to a group of healthy controls (n=14) using an acceptability judgement task. The groups were matched with respect to age, education, and extent of musical training. Violations were based on morpho-syntactic relations in sentences and harmonic relations in chord sequences. Both groups presented with a significant P600 response to syntactic violations across both domains. The aphasic participants presented with a reduced-amplitude posterior P600 compared to the healthy adults in response to linguistic, but not musical, violations. Participants with aphasia did however present with larger frontal positivities in response to violations in both domains. Intriguingly, extent of musical training was associated with larger posterior P600 responses to syntactic violations of language and music in both groups. Overall, these findings are not consistent with the predictions of the SSIRH, and instead suggest that linguistic, but not musical, syntactic processing may be selectively impaired in stroke-induced agrammatic aphasia. However, the findings also suggest a relationship between musical training and linguistic syntactic processing, which may have clinical implications for people with aphasia, and motivates more research on the relationship between these two domains.

Effortful Retrieval Practice Effects in Lexical Access: A Role for Semantic Competition

Word retrieval difficulty (lexical access deficit) is prevalent in aphasia. Studies have shown that practice retrieving names from long-term memory (retrieval practice) improves future name retrieval for production in people with aphasia (PWA), particularly when retrieval is effortful. To explicate such effects, this study examined a potential role for semantic competition in the learning mechanism(s) underlying effortful retrieval practice effects in lexical access in 6 PWA. Items were trained in a blocked-cyclic naming task, in which repeating sets of pictures drawn from semantically-related versus unrelated categories underwent retrieval practice with feedback. Naming accuracy was lower for the related items at training, but next-day accuracy did not differ between the conditions. However, greater semantic-relatedness of an item to its set in the related condition was associated with lower accuracy at training but higher accuracy at test. Relevance to theories of lexical access and implications for naming treatment in aphasia are discussed.

Cerebral Amyloid Angiopathy in Amyloid-Positive Patients from a Memory Clinic Cohort

BACKGROUND

The overlap between cerebral amyloid angiopathy (CAA) and Alzheimer's disease (AD) is frequent and relevant for patients with cognitive impairment.

OBJECTIVE

To assess the role of the diagnosis of CAA on the phenotype of amyloid-β (Aβ) positive patients from a university-hospital memory clinic.

METHODS

Consecutive patients referred for suspected cognitive impairment, screened for Aβ pathological changes in cerebrospinal fluid (CSF), with available MRI and neuropsychological results were included. We determined the association between probable CAA and clinical, neuropsychological (at presentation and after a mean follow-up of 17 months in a sub-sample) and MRI (atrophy, white matter hyperintensities, perivascular spaces) characteristics.

RESULTS

Of 218 amyloid-positive patients, 8.3% fulfilled criteria for probable CAA. A multivariable logistic regression showed an independent association of probable CAA with lower Aβ1-42 (adjusted odds ratio [aOR] = 0.94, 95% confidence interval [95% CI] = 0.90-0.98, p = 0.003), and Aβ1-40 (aOR = 0.98, 95% CI=0.97-0.99 p = 0.017) levels in CSF, and presence of severe burden of enlarged perivascular spaces (EPVS) in the centrum semiovale (aOR = 3.67, 95% CI = 1.21-11.15, p = 0.022). Linear mixed-model analysis showed that both groups significantly deteriorated in global clinical severity, executive function and memory. Nevertheless, the presence of probable CAA did not differently affect the rate of cognitive decline.

CONCLUSION

The presence of probable CAA in Aβ positive patients was associated with lower Aβ1-42 and Aβ1-40 CSF levels and increased centrum semiovale EPVS burden, but did not independently influence clinical phenotype nor the rate of cognitive decline within our follow-up time window.

Methodological Considerations for Incorporating Clinical Data Into a Network Model of Retrieval Failures

Difficulty retrieving information (e.g., words) from memory is prevalent in neurogenic communication disorders (e.g., aphasia and dementia). Theoretical modeling of retrieval failures often relies on clinical data, despite methodological limitations (e.g., locus of retrieval failure, heterogeneity of individuals, and progression of disorder/disease). Techniques from network science are naturally capable of handling these limitations. This paper reviews recent work using a multiplex lexical network to account for word retrieval failures and highlights how network science can address the limitations of clinical data. Critically, any model we employ could impact clinical practice and patient lives, harkening the need for theoretically well-informed network models.

Reading proficiency influences the effects of transcranial direct current stimulation: Evidence from selective modulation of dorsal and ventral pathways of reading in bilinguals

INTRODUCTION

tDCS can modulate reading which is processed by lexical (ventral) and sub-lexical (dorsal) pathways. Previous research indicates that pathway recruitment in bilinguals depends on a script's orthographic depth and a reader's proficiency with it. The effect of tDCS on each reading pathway has not been investigated in bilinguals. We stimulated the left dorsal and ventral pathways separately in Chinese-English (C-E) bilinguals to understand whether pathway-specific modulation by tDCS is possible and, if so, how it is influenced by orthographic depth and script proficiency.

METHODS

A double-blind, sham-controlled, within-subject experiment was designed wherein 16 balanced bilinguals received anodal tDCS in dorsal, ventral and sham sessions. Two tDCS montages of electrode sizes 5 × 5 cm² with 1) anode at CP5 and cathode at CZ, and 2) anode at TP7 and cathode at nape of the neck, were applied for stimulating the dorsal and ventral pathways respectively. Bilinguals were asked to read word lists for each language before and after stimulation. RTs for accurate trials were analysed using linear mixed-effect modelling that included proficiency scores for reading English pseudo-words (PW) and Chinese pinyin.

RESULTS

For both languages, word reading RTs were faster following dorsal pathway stimulation. The dorsal stimulation effect (change in RT) was negatively correlated with pseudoword reading and pinyin proficiency. Stimulation of the ventral pathway decreased RTs only for Chinese reading.

CONCLUSION

Dorsal and ventral reading pathways can be selectively modulated by tDCS in bilingual readers with dorsal (sub-lexical) pathway stimulation affecting reading in both scripts and ventral (lexical) pathway stimulation selectively affecting Chinese reading. Dorsal pathway tDCS effects are modulated by sub-lexical reading proficiency.

Pseudoword spelling ability predicts response to word spelling treatment in acquired dysgraphia

Although rehabilitation of acquired dysgraphia can be quite effective, identifying predictors of responsiveness to treatment is useful for prognosis and individualization of treatment protocols. This study examined whether various features of treatment response were predicted by the integrity of one or more of the central cognitive components of spelling: orthographic long-term memory, orthographic working memory, and phoneme-grapheme conversion. Twenty dysgraphic individuals received 12 weeks of bi-weekly, individualized, lexically-based spelling rehabilitation using a spell-study-spell paradigm. Linear multiple regression modelling examined whether the type and severity of the dysgraphic deficit, assessed before rehabilitation, predicted the magnitude and rate of improvement, generalization to untrained items and maintenance of treatment gains. The results revealed that pseudoword spelling accuracy - indexing the integrity of the phoneme-grapheme conversion system - was the only factor examined that significantly predicted the rate of accuracy gains for trained words as well as the extent of generalization to untrained words. Pre-treatment pseudoword spelling accuracy also predicted retention of gains for trained and untrained words at 3-month follow-up. These findings reveal that the integrity of the phoneme-grapheme conversion system prior to dysgraphia rehabilitation may play a key role in rehabilitation-driven recovery, even when the treatment approach targets lexical rather than pseudoword spelling processes.

How functional network connectivity changes as a result of lesion and recovery: An investigation of the network phenotype of stroke

This study, through a series of univariate and multivariate (classification) analyses, investigated fMRI task-based functional connectivity (FC) at pre- and post-treatment time-points in 18 individuals with chronic post-stroke dysgraphia. The investigation examined the effects of lesion and treatment-based recovery on functional organization, focusing on both inter-hemispheric (homotopic) and intra-hemispheric connectivity. The work confirmed, in the chronic stage, the "network phenotype of stroke injury" proposed by Siegel et al. (2016) consisting of abnormally low inter-hemispheric connectivity as well as abnormally high intra-hemispheric (ipsilesional) connectivity. In terms of recovery-based changes in FC, this study found overall hyper-normalization of these abnormal inter and intra-hemispheric connectivity patterns, suggestive of over-correction. Specifically, treatment-related homotopic FC increases were observed between left and right dorsal frontal-parietal regions. With regard to intra-hemispheric connections, recovery was dominated by increased ipsilateral connectivity between frontal and parietal regions along with decreased connectivity between the frontal regions and posterior parietal-occipital-temporal areas. Both inter and intra-hemispheric changes were associated with treatment-driven improvements in spelling performance. We suggest an interpretation according to which, with treatment, as posterior orthographic processing areas become more effective, executive control from frontal-parietal networks becomes less necessary.

The Role of Amygdala in Self-Conscious Emotions in a Patient With Acquired Bilateral Damage

Shame plays a fundamental role in the regulation of our social behavior. One intriguing question is whether amygdala might play a role in processing this emotion. In the present single-case study, we tested a patient with acquired damage of bilateral amygdalae and surrounding areas as well as healthy controls on shame processing and other social cognitive tasks. Results revealed that the patient's subjective experience of shame, but not of guilt, was more reduced than in controls, only when social standards were violated, while it was not different than controls in case of moral violations. The impairment in discriminating between normal social situations and violations also emerged. Taken together, these findings suggest that the role of the amygdala in processing shame might reflect its relevance in resolving ambiguity and uncertainty, in order to correctly detect social violations and to generate shame feelings.

Assessing consistency of effects when applying multilevel models to single-case data

In the context of single-case experimental designs, replication is crucial. On the one hand, the replication of the basic effect within a study is necessary for demonstrating experimental control. On the other hand, replication across studies is required for establishing the generality of the intervention effect. Moreover, the "replicability crisis" presents a more general context further emphasizing the need for assessing consistency in replications. In the current text, we focus on replication of effects within a study, and we specifically discuss the consistency of effects. Our proposal for assessing the consistency of effects refers to one of the promising data analytical techniques, multilevel models, also known as hierarchical linear models or mixed effects models. One option is to check, for each case in a multiple-baseline design, whether the confidence interval for the individual treatment effect excludes zero. This is relevant for assessing whether the effect is replicated as being non-null. However, we consider that it is more relevant and informative to assess, for each case, whether the confidence interval for the random effects includes zero (i.e., whether the fixed effect estimate is a plausible value for each individual effect). This is relevant for assessing whether the effect is consistent in size, with the additional requirement that the fixed effect itself is different from zero. The proposal for assessing consistency is illustrated with real data and is implemented in free user-friendly software.

Reliability of BOLD signals in chronic stroke-induced aphasia

Investigating the neurobiology of language impairment and treatment in chronic stroke aphasia using fMRI requires an understanding of measurement variability within and between participants. In this multicenter study, we evaluated the scan-rescan reliability of an auditory and visual (written) story comprehension paradigm in stroke participants with aphasia (N = 65) and healthy controls (N = 22). The multi-modal task was conducted twice (~1 week apart) on separate visits upon study enrolment and twice again at completion three months later. A non-language visuomotor task was studied in the aphasia group only, which was conducted once per time point (3 months apart). While participants were asked to make responses during the comprehension task, these in-scanner responses were not recorded. Reliability was assessed using intraclass correlation coefficient (ICC) at both group and individual participant levels. The visual story comprehension condition had higher reliability than the auditory condition in both groups, with participants with aphasia exhibiting lower reliability than controls in both conditions (stroke ICC = .43, healthy ICC = .81). Differences in reliability within the group of participants with aphasia were found to be partially explained by overall language impairment as well as greater head motion. In the participants with aphasia, the visuomotor paradigm was found to have greater reliability than the story comprehension task at equivalent interscan intervals (visuomotor = 0.50, comprehension = 0.34), and its reliability was not associated with language impairment. This work highlights the importance of considering the reliability of fMRI tasks in aphasia research, provides strategies to improve reliability and has potential implications for the field of clinical neuroimaging in general.

Re-learning and remembering in the lesioned brain

It is well known that re-learning language skills after a brain lesion can be very difficult. However, while learning and memory challenges have been extensively researched in amnesic individuals, very little research attention has been directed at understanding the characteristics of learning and memory that are relevant to recovery and rehabilitation of acquired language impairments. Even in the absence of damage to the medial temporal lobe regions classically associated with learning and memory, these individuals often suffer damage to frontal and other subcortical areas associated with learning and memory that may contribute to the learning challenges they face. Therefore, an understanding of the learning and memory profiles of post-stroke language impairments is important for the development and optimization of rehabilitation approaches. In two studies, we examine the degree to which certain basic characteristics of learning and memory, identified in neurotypical individuals, are intact in individuals with post-stroke language impairment. We specifically consider fundamental principles regarding the optimal spacing of learning trials that have been shown to reliably operate in neurotypical adults, across a wide range of language domains. We report on two studies that examine whether or not these principles also apply in language re-learning and retention for individuals with acquired deficits in written language production. Study 1 compared distributed vs. clustered training schedules, while Study 2 examined-for the first time in the context of re-learning-the relationship between the spacing of training trials and the retention period. This investigation revealed that, despite significant cognitive deficits and brain lesions, remarkably similar principles govern re-learning and retention in the lesioned brain as have been found to apply in neurologically healthy individuals. These results allow us to begin to integrate our understanding of recovery with the broader literature on learning and memory and have implications for the optimal organization of rehabilitation. Specifically, the findings raise questions regarding the traditional compression of rehabilitation within relatively short time windows.