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

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

Errorless, Errorful, and Retrieval Practice for Naming Treatment in Aphasia: A Scoping Review of Learning Mechanisms and Treatment Ingredients

PURPOSE: Increasingly, mechanisms of learning are being considered during aphasia rehabilitation. Well-characterized learning mechanisms can inform how interventions should be administered to maximize the acquisition and retention of treatment gains. This systematic scoping review mapped hypothesized mechanisms of action (MoAs) and treatment ingredients in three learning-based approaches targeting naming in aphasia: errorless learning (ELess), errorful learning (EFul), and retrieval practice (RP). The rehabilitation treatment specification system was leveraged to describe available literature and identify knowledge gaps within a unified framework. METHOD: PubMed and CINHAL were searched for studies that compared ELess, EFul, and/or RP for naming in aphasia. Independent reviewers extracted data on proposed MoAs, treatment ingredients, and outcomes. RESULTS: Twelve studies compared ELess and EFul, six studies compared ELess and RP, and one study compared RP and EFul. Hebbian learning, gated Hebbian learning, effortful retrieval, and models of incremental learning via lexical access were proposed as MoAs. To maximize treatment outcomes within theorized MoAs, researchers manipulated study ingredients including cues, scheduling, and feedback. Outcomes in comparative effectiveness studies were examined to identify ingredients that may influence learning. Individual-level variables, such as cognitive and linguistic abilities, may affect treatment response; however, findings were inconsistent across studies. CONCLUSIONS: Significant knowledge gaps were identified and include (a) which MoAs operate during ELess, EFul, and RP; (b) which ingredients are active and engage specific MoAs; and (c) how individual-level variables may drive treatment administration. Theory-driven research can support or refute MoAs and active ingredients enabling clinicians to modify treatments within theoretical frameworks

Variation in How Cognitive Control Modulates Sentence Processing

Prior research suggests that cognitive control can assist the comprehension of sentences that create conflict between interpretations, at least under some circumstances. However, the mixed pattern of results suggests that cognitive control may not always be necessary for accurate comprehension. We tested whether cognitive control recruitment for language processing is systematically variable, depending on the type of sentential ambiguity or conflict, individual differences in cognitive control, and task demands. Participants completed two sessions in a web-based experiment. The first session tested conflict modulation using interleaved Stroop and sentence comprehension trials. Critical sentences contained syntax-semantics or phrase-attachment conflict. In the second session, participants completed three cognitive control and three working memory tasks. Exploratory factor analysis was used to index individual differences in a cognitive control factor and a working memory factor. At the group level, there were no significant conflict modulation effects for either syntax-semantics or phrase-attachment conflict. At the individual differences level, the cognitive control factor correlated with offline comprehension accuracy but not online processing measures for both types of conflict. Together, the results suggest that the role of cognitive control in sentence processing may vary according to task demands. When overt decisions are required, individual differences in cognitive control may matter such that better cognitive control results in better language comprehension performance. The results add to the mixed evidence on conflict modulation and raise questions about the situations under which cognitive control influences online processing

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

A Paradigm for Investigating Executive Control Mechanisms in Word Retrieval in Language-Impaired and Neurotypical Speakers

An unresolved question in research on executive control in language production is whether the processes responsible for inhibiting a dominant, prepotent response in order to comply with task goals is the same or different from control processes that bias intrinsic competition during lexical selection. Heretofore, these processes have been studied with different paradigms, such as the Stroop task and semantic blocking paradigm [1], respectively. The present study introduces a new paradigm to study both mechanisms as they impact word retrieval in neuropsychological and neurotypical populations. The task included several blocks of trials, where within a block two pictures were named repeatedly in random order. Two manipulated factors were: (1) relatedness of the pair of names, which bore either a semantic (duck/pig) or phonological relationship (ball/bag); or were unrelated (map/gun); (2) canonicity, where participants named each picture either with the canonical name (e.g., say “pig” for pig, “duck” for duck) or reversed the labels (e.g., say “duck” for pig, “pig” for duck). The names were closely matched for length, frequency, and other variables. Crossing the factors created six conditions (semantic-canonical, semantic-reverse, phonological-canonical, phonological-reverse, unrelated-canonical, unrelated-reverse), with each condition administered in one block of 16 trials (8 trials per picture). The task was administered to 12 participants with aphasia (PWA) with mild to severe naming impairment and 25 neurotypical controls. The dependent variables were naming latency (calculated for correct naming trials only) and naming accuracy, defined as a binary variable (correct versus error), which were analyzed with mixed linear and logistic regression analysis, respectively. For each dependent variable in each participant group, contrasting each related condition with the unrelated condition permitted measurement of three effects--a main effect of relatedness, canonicity, and their interaction. For example, focusing on the semantic and unrelated conditions, a main effect of relatedness (collapsing across canonicity) provided an index of difficulty in resolving intrinsic semantic competition. A main effect of canonicity (collapsing across relatedness) provided an index of difficulty in inhibiting a prepotent response. Presence of an interaction (unrelated/semantic X canonical/reverse) would suggest that the two control mechanisms are interdependent. Parallel effects were measured in a comparison of the phonological and unrelated condition as well. An a priori expectation was for poorer performance in the semantic condition versus unrelated, similar to semantic blocking effects in prior work [1]. This expectation was confirmed with a main effect of relatedness, with the PWA group showing lower accuracy (p<0.05) and controls showing marginally lower accuracy (p=0.059) and reliably longer latencies (p<0.05) in the semantic versus unrelated condition. Neither group showed a main effect of relatedness in either measure when comparing the phonological condition to unrelated, aligning with prior work showing that phonological relatedness does not consistently induce competitive interference [2]. All main effects of canonicity were reliable in both dependent measures for both groups (all ps<0.01), with poorer performance in the reverse versus canonical condition. Scant evidence of an interaction across the analyses suggests that the two control processes exert independent effects on performance

Variation in how cognitive control modulates sentence processing

Prior research suggests that cognitive control can assist the comprehension of sentences that create conflict between interpretations, at least under some circumstances. However, the mixed pattern of results suggests that cognitive control may not always be necessary for accurate comprehension. We tested whether cognitive control recruitment for language processing is systematically variable, depending on the type of sentential ambiguity or conflict, individual differences in cognitive control, and task demands. Participants completed two sessions in a web-based experiment. The first session tested conflict modulation using interleaved Stroop and sentence comprehension trials. Critical sentences contained syntax-semantics or phrase-attachment conflict. In the second session, participants completed three cognitive control and three working memory tasks. Exploratory factor analysis was used to index individual differences in a cognitive control factor and a working memory factor. At the group level, there were no significant conflict modulation effects for either syntax-semantics or phrase-attachment conflict. At the individual differences level, the cognitive control factor correlated with offline comprehension accuracy but not online processing measures for both types of conflict. Together, the results suggest that the role of cognitive control in sentence processing may vary according to task demands. When overt decisions are required, individual differences in cognitive control may matter such that better cognitive control results in better language comprehension performance. The results add to the mixed evidence on conflict modulation and raise questions about the situations under which cognitive control influences online processing

Learning from your mistakes: The functional value of spontaneous error monitoring in aphasia

Self-monitoring of errors in picture naming has been shown to correlate positively with aphasia treatment outcomes (Marshall et al., 1994). To explore potential explanations, we took advantage of aphasics’ item-level inconsistency in naming accuracy, e.g., in the baseline phase of treatment studies. We looked for a “monitoring benefit” such that items erroneously named on baseline 1 would be more likely to be named correctly on baseline 2 if accompanied by spontaneous monitoring, relative to unmonitored errors. Such a monitoring benefit might reflect learning (e.g., in response to the self-generated error signal) and/or the differential strength (e.g., proximity to threshold) of monitored items compared to those that are not monitored. To implicate learning requires evidence that the monitoring benefit is directionally asymmetric, i.e., the monitoring-related change in accuracy from baseline 1 to 2 (forward direction) is greater than the monitoring-related change from baseline 2 to trial 1 (backward). Twelve participants with chronic stroke aphasia participated. All were mild-to-moderate in aphasia severity and naming impairment. Each participant named the same 615 pictures, without feedback, on two occasions (2 “baselines”) in separate weeks. On each trial, we scored the accuracy of the first attempt and the type of error; additionally, each error was assigned a monitoring code: DetNoCorr (detected without correction; Ex. 1, 3); DetCorr (detected with correction (Ex., 2, 4); or NoDet (not detected). Ex. 1. (T = squirrel) “chipmunk, no”: Semantic error; DetNoCorr Ex. 2. (T = squirrel) “chipmunk, no, squirrel”: Semantic error; DetCorr Ex. 3. (T = umbrella) “umbelella, that’s not right”: Phonological error; DetNoCorr Ex. 4. (T = umbrella) “umbelella, umbrella”: Phonological error; DetCorr We used mixed effects logistic regression to assess whether the log odds of changing from error to correct was predicted by monitoring status of the error (DetCorr vs. NoDet; DetNoCorr vs. NoDet); whether the monitoring benefit interacted with direction of change (forward, backward); and whether effects varied by error type. Figure 1 (top) shows that the proportion accuracy change was higher for DetCorr, relative to NoDet, consistent with a monitoring benefit. The difference in log odds was significant for semantic errors in both directions (forward: coeff. = -1.73; z= -7.78; p < .001; backward: coeff = -0.92; z= -3.60; p < .001), and for phonological errors in both directions (forward: coeff. = -0.74; z= -2.73; p=.006; backward : coeff. = -.76; z = -2.73; p = .006). The difference between DetNoCorr and NoDet was not significant in any condition. Figure 1 (bottom) shows that for Semantic errors, there was a directional asymmetry favoring the Forward condition (interaction: coeff. = .79; z = 2.32; p = .02). Phonological errors, in contrast, produced comparable effects in Forward and Backward direction. The results demonstrated a benefit for errors that were detected and corrected. This monitoring benefit was present in both the forward and backward direction, supporting the Strength hypothesis. Of greatest interest, the monitoring benefit for Semantic errors was greater in the forward than backward direction, indicating a role for learning