Visual Feedback and Guided Balance Training in an Immersive Virtual Reality Environment for Lower Extremity Rehabilitation.

Balance training is essential for physical rehabilitation procedures, as it can improve functional mobility and enhance cognitive coordination. However, conventional balance training methods may have limitations in terms of motivation, real-time objective feedback, and personalization, which a virtual reality (VR) setup may better provide. In this work, we present an immersive VR training environment for lower extremity balance rehabilitation with real-time guidance and feedback. The VR training environment immerses the user in a 3D ice rink model where a virtual coach (agent) leads them through a series of balance poses, and the user controls a trainee avatar with their own movements. We developed two coaching styles: positive-reinforcement and autonomous-supportive, and two viewpoints of the trainee avatar: first-person and third-person. The proposed environment was evaluated in a user study with healthy, non-clinical participants (n = 16, 24.4 ± 5.7 years old, 9 females). Our results show that participants showed stronger performance in the positive-reinforcement style compared to the autonomous-supportive style. Additionally, in the third-person viewpoint, the participants exhibited more stability in the positive-reinforcement style compared to the autonomous-supportive style. For viewpoint, participants exhibited stronger performance in the first-person viewpoint compared to third-person in the autonomous-supportive style, while they were comparable in the positive-reinforcement style. We observed no significant effects on the foot height and number of mistakes. Furthermore, we report the analysis of user performance with balance training poses and subjective measures based on questionnaires to assess the user experience, usability, and task load. The proposed VR balance training could offer an interactive, adaptive, and engaging environment and open new potential research directions for lower extremity rehabilitation.

Declarative Learning Mechanisms Support Declarative but Not Probabilistic Feedback-Based Learning in Children with Developmental Language Disorder (DLD).

Declarative and probabilistic feedback-based learning was evaluated in 8-12-year-old school-age children with developmental language disorder (DLD; n = 14) and age-matched children with typical development (TD; n = 15). Children performed a visual two-choice word-learning task and a visual probabilistic classification task while their electroencephalogram (EEG) was recorded non-invasively from the scalp. Behavioral measures of accuracy and response to feedback, and electrophysiological responses to feedback were collected and compared between the two groups. While behavioral data indicated poorer performance by children with DLD in both learning paradigms, and similar response patterns to positive and negative feedback, electrophysiological data highlighted processing patterns in the DLD group that differed by task. More specifically, in this group, feedback processing in the context of declarative learning, which is known to be dominated by the medial temporal lobe (MTL), was associated with enhanced N170, an event-related brain potential (ERP) associated with MTL activation. The N170 amplitude was found to be correlated with declarative task performance in the DLD group. During probabilistic learning, known to be governed by the striatal-based learning system, the feedback-related negativity (FRN) ERP, which is the product of the cortico-striatal circuit dominated feedback processing. Within the context of probabilistic learning, enhanced N170 was associated with poor learning in the TD group, suggesting that MTL activation during probabilistic learning disrupts learning. These results are interpreted within the context of a proposed feedback parity hypothesis suggesting that in children with DLD, the system that dominates learning (i.e., MTL during declarative learning and the striatum during probabilistic learning) dominates and supports feedback processing.

With or without Feedback?-How the Presence of Feedback Affects Processing in Children with Developmental Language Disorder.

Language acquisition depends on the ability to process and learn probabilistic information, often through the integration of performance feedback. Children with developmental language disorder (DLD) have demonstrated weaknesses in both probabilistic learning and feedback processing, but the individual effects of each skill are poorly understood in this population. This study examined school-aged children with DLD (n = 29) and age- and gender-matched children with typical development (TD; n = 44) on a visual probabilistic classification learning task presented with and without feedback. In the feedback-based version of the task, children received performance feedback on a trial-by-trial basis during the training phase of the task. In the feedback-free version, children responded after seeing the correct choice marked with a green border and were not presented with feedback. Children with TD achieved higher accuracy than children with DLD following feedback-based training, while the two groups achieved similar levels of accuracy following feedback-free training. Analyses of event-related potentials (ERPs) provided insight into stimulus encoding processes. The feedback-free task was dominated by a frontal slow wave (FSW) and a late parietal component (LPC) which were not different between the two groups. The feedback-based task was dominated by a parietal slow wave (PSW) and an LPC, both of which were found to be larger in the TD than in the DLD group. In combination, results suggest that engagement with feedback boosts learning in children with TD, but not in children with DLD. When the need to process feedback is eliminated, children with DLD demonstrate behavioral and neurophysiological responses similar to their peers with TD.

Between Shifting and Feedback Processing in the Wisconsin Card Sorting Test in Children with Developmental Language Disorder.

Children with developmental language disorder (DLD) demonstrate deficits in executive functioning; however, the specific components of executive functioning that are affected in this population are not well understood. This study evaluated set shifting and feedback processing in a Wisconsin Card Sorting Test (WCST) performed by 24 children with and without DLD. The behavioral results revealed poorer performance by the DLD group in measures of accuracy, proportion of correct rule shifts, perseverative errors on shift trials, and proportion of effective responses to feedback. Electrophysiological measures (event-related potentials, or ERPs) indicated different patterns of response to negative feedback that signaled the need for rule shifting, with the DLD group showing a trend toward processing shift cues as negative feedback. Group differences were found in the processing of the first and last positive feedback, with overall stronger responses to positive feedback by children with DLD. However, both groups showed a similar pattern of diminished attention to positive feedback when rule learning was established. Taken together, children with DLD demonstrated the inefficient processing of negative feedback in the context of rule-shifting and difficulty in establishing and maintaining a rule.

The contribution of theta and delta to feedback processing in children with developmental language disorder.

PURPOSE: The study aimed at evaluating feedback processing at the electrophysiological level and its relation to learning in children with developmental language disorder (DLD) to further advance our understanding of the underlying neural mechanisms of feedback-based learning in children with this disorder. METHOD: A feedback-based probabilistic learning task required children to classify novel cartoon animals into two categories that differ on five binary features, the probabilistic combination of which determined classification. The learning outcomes' variance in relation to time- and time-frequency measures of feedback processing were examined and compared between 20 children with developmental language disorder and 25 age-matched children with typical language development. RESULTS: Children with developmental language disorder (DLD) performed poorer on the task when compared with their age-matched peers with typical language development (TD). The electrophysiological data in the time domain indicated no differences in the processing of positive and negative feedback among children with DLD. However, the time-frequency analysis revealed a strong theta activity in response to negative feedback in this group, suggesting an initial distinction between positive and negative feedback that was not captured by the ERP data. In the TD group, delta activity played a major role in shaping the FRN and P3a and was found to predict test performance. Delta did not contribute to the FRN and P3a in the DLD group. Additionally, theta and delta activities were not associated with the learning outcomes of children with DLD. CONCLUSION: Theta activity, which is associated with the initial processing of feedback at the level of the anterior cingulate cortex, was detected in children with developmental language disorder (DLD) but was not associated with their learning outcomes. Delta activity, which is assumed to be generated by the striatum and to be linked to elaborate processing of outcomes and adjustment of future actions, contributed to processing and learning outcomes of children with typical language development but not of children with DLD. The results provide evidence for atypical striatum-based feedback processing in children with DLD.

Feedback Processing During Probabilistic Learning in Children With Developmental Language Disorder: An Event-Related Potential Study.

PURPOSE: The purpose of this study was to examine feedback processing within the context of probabilistic learning in children with and without developmental language disorder (DLD). METHOD: The probabilistic category learning task required 28 children ages 8-13 years old to classify novel cartoon animals that differed in five binary features into one of two categories. Performance feedback guided incremental learning of the stimuli classifications. Feedback processing was compared between children with DLD and age-matched children with typical development (TD) by measuring the magnitude of feedback-related event-related potentials. Additionally, the likelihood of each group to repeat a classification of a stimulus following positive feedback ("stay" behavior) and change a classification following negative feedback ("switch" behavior) served as a measure of the consequence of feedback processing. RESULTS: Children with DLD achieved lower classification accuracy on all learning outcomes compared to their peers with TD. Children with DLD were less likely than those with TD to demonstrate "stay" behavior or to repeat a correct response following positive feedback. "Switch" behavior or changing an incorrect response following negative feedback was found to be at chance level in both groups. Electrophysiological data indicated that children with DLD had a smaller feedback-related negativity effect (i.e., smaller differential processing of positive and negative feedback) when compared to children with TD. Although no differences were found between the two groups in the amplitude of the P3a, strong positive correlations were found between "stay/switch" behavior and the P3a for children in the TD group only. CONCLUSIONS: Children with DLD do not appear to benefit from incremental corrective feedback to the same extent as their peers with TD. Processing differences are captured in the initial stages of feedback evaluation and in translating information carried by the feedback to inform future actions.

An Implicit-Explicit Framework for Intervention Methods in Developmental Language Disorder.

PURPOSE: The growing interest in framing intervention approaches as either implicit or explicit calls for a discussion of what makes intervention approaches engage each of these learning systems, with the goal of achieving a shared framework. This tutorial presents evidence for the interaction between implicit and explicit learning systems, and it highlights the intervention characteristics that promote implicit or explicit learning as well as outcome measures that tap into implicit or explicit knowledge. This framework is then applied to eight common intervention approaches and notable combinations of approaches to unpack their differential engagement of implicit and explicit learning. CONCLUSIONS: Many intervention characteristics (e.g., instructions, elicitation techniques, feedback) can be manipulated to move an intervention along the implicit-explicit continuum. Given the bias for using explicit learning strategies that develops throughout childhood and into adulthood, clinicians should be aware that most interventions (even those that promote implicit learning) will engage the explicit learning system. However, increased awareness of the implicit and explicit learning systems and their cognitive demands will allow clinicians to choose the most appropriate intervention for the target behavior.

Online Training Modules for Teaching Assessment Skills to Graduate Student Clinicians.

PURPOSE: Assessment is a crucial skill for speech-language pathologists, who rely on standardized tests to identify characteristics of speech, language, hearing, literacy, and related skill sets. Training in assessment administration is an integral part of graduate education that lays the foundation for appropriate use of these tools. Teaching students to administer standardized assessments is time intensive, can vary depending on student learning pace, and involves both general and test-specific knowledge. The current pilot study investigated the effectiveness of researcher-developed and scalable online training modules for beginning and advanced graduate students for knowledge and self-efficacy outcomes. METHOD: Graduate students (n = 61) across four cohorts (two beginning and two advanced) were trained using online, asynchronous assessment training modules. The modules addressed the administration of standardized assessments using written tutorials, video demonstrations, and quizzes. Students completed pre- and posttests on knowledge and self-efficacy for administering and scoring the trained assessments before and after the online training modules. RESULTS: We found significant pretest to posttest gains in specific assessment-related knowledge for beginning and advanced groups. Following completion of the training modules, beginning graduate students demonstrated increased self-efficacy for general assessment principles, whereas advanced graduate students started and remained high in self-efficacy at posttest. CONCLUSIONS: Using researcher-developed online training modules, both beginning and advanced graduate students improved knowledge for assessment skills. These training modules can be used as a model for developing teaching materials across a range of assessments and related topics that are scalable in the context of remote teaching and learning.

Inner Speech and Executive Function in Children With Developmental Language Disorder: Implications for Assessment and Intervention.

Purpose: Many children with developmental language disorder (DLD) also have difficulty with executive function. The presence of co-occurring deficits in language and executive function can obscure assessment results and lead to the implementation of ineffective interventions. It is also the case that inner speech, or the use of self-directed language to guide thought and action, often mediates performance on executive function tasks. The aims of this tutorial are to (a) summarize what is known about how inner speech affects executive function performance in typical populations and children with DLD and (b) highlight potential implications for clinical practice and directions for future research. We provide a brief background on inner speech, including theoretical frameworks, typical development, and measurement approaches. We then summarize research on inner speech and executive function involving typical adults and children, followed by a description of the few studies involving children with DLD. Conclusions: Work with typical adults and children has concluded that inner speech operates as a self-cueing device to support understanding of task rules, sequencing of task order, and maintenance of task goals. Work involving children with DLD suggests that their inner speech is less mature, less relevant, and less effective overall when completing executive function tasks. However, very few studies have examined the relations between inner speech and executive function in children with DLD. It is important for speech-language pathologists to understand the potential role of inner speech during executive function tasks, given how often these skills are utilized during everyday activities. Although more research is needed, speech-language pathologists are in a unique position to support both language and executive function goals for children with DLD.

Spoken Word Learning in Children With Developmental Language Disorder or Dyslexia.

Purpose Word learning difficulties have been documented in multiple studies involving children with dyslexia and developmental language disorder (DLD; see also specific language impairment). However, no previous studies have directly contrasted word learning in these two frequently co-occurring disorders. We examined word learning in second-grade students with DLD-only and dyslexia-only as compared to each other, peers with both disorders (DLD + dyslexia), and peers with typical development. We hypothesized that children with dyslexia-only and DLD-only would show differences in word learning due to differences in their core language strengths and weaknesses. Method Children (N = 244) were taught eight novel pseudowords paired with unfamiliar objects. The teaching script included multiple exposures to the phonological form, the pictured object, a verbal semantic description of the object, and spaced retrieval practice opportunities. Word learning was assessed immediately after instruction with tasks requiring recall or recognition of the phonological and semantic information. Results Children with dyslexia-only performed significantly better on existing vocabulary measures than their peers with DLD-only. On experimental word learning measures, children in the dyslexia-only and DLD + dyslexia groups showed significantly poorer performance than typically developing children on all word learning tasks. Children with DLD-only differed significantly from the TD group on a single word learning task assessing verbal semantic recall. Conclusions Overall, results indicated that children with dyslexia display broad word learning difficulties extending beyond the phonological domain; however, this contrasted with their relatively strong performance on measures of existing vocabulary knowledge. More research is needed to understand relations between word learning abilities and overall vocabulary knowledge and how to close vocabulary gaps for children with both disorders. Supplemental Material https://doi.org/10.23641/asha.14832717.

Accelerating Adolescent Vocabulary Growth: Development of an Individualized, Web-Based, Vocabulary Instruction Program.

Purpose Improving vocabulary knowledge is important for many adolescents, but there are few evidence-based vocabulary instruction programs available for high school students. The purpose of this article is to describe the iterative development of the DictionarySquared research platform, a web-based vocabulary program that provides individualized vocabulary instruction, and to report the results of 2 pilot studies examining the feasibility of implementation and potential effectiveness with high school students. Method We describe our theory of change and 5 phases of iterative development. In Phases 1 and 2, we evaluated the initial implementation of DictionarySquared and revised the instructional materials. In Phase 3, we conducted a feasibility study involving 169 high school students who used the program for 4 weeks. Student usage data and feedback from teachers were used to guide program revisions in Phase 4. In Phase 5, we examined potential effectiveness for 264 high school students who were assigned to use the program for 1 semester. Results Results of the Phase 3 study indicated that implementation of the program was feasible, although usage was below assigned levels. Results of the Phase 5 study indicated that the duration of active program usage significantly predicted posttest vocabulary scores on the proximal assessment after controlling for pretest standardized vocabulary scores. Analyses using propensity score matching revealed positive, but nonsignificant, gains on standardized assessments between pre- and posttests. Conclusion Together, the results of early-stage pilot studies are promising and suggest that a more rigorous test of efficacy is warranted. Successful implementation of the DictionarySquared research program, as well as lessons learned from the program development process, will expand the range of evidence-based treatment options that clinicians and educators can use to improve adolescent vocabulary and reading comprehension skills. Supplemental Material https://doi.org/10.23641/asha.9765161.

Children With Dyslexia Benefit From Orthographic Facilitation During Spoken Word Learning.

Purpose: Orthographic facilitation describes the phenomenon in which a spoken word is produced more accurately when its corresponding written word is present during learning. We examined the orthographic facilitation effect in children with dyslexia because they have poor learning and recall of spoken words. We hypothesized that including orthography during spoken word learning would facilitate learning and recall. Method: Children with dyslexia and children with typical development (n = 46 per group), 7-9 years old, were matched for grade and nonverbal intelligence. Across 4 blocks of exposure in 1 session, children learned pairings between 4 spoken pseudowords and novel semantic referents in a modified paired-associate learning task. Two of the pairings were presented with orthography present, and 2 were presented with orthography absent. Recall of newly learned spoken words was assessed using a naming task. Results: Both groups showed orthographic facilitation during learning and naming. During learning, both groups paired pseudowords and referents more accurately when orthography was present. During naming, children with typical development showed a large orthographic facilitation effect that increased across blocks. For children with dyslexia, this effect was present initially but then plateaued. Conclusions: We demonstrate for the first time that children with dyslexia benefit from orthographic facilitation during spoken word learning. These findings have direct implications for teaching spoken vocabulary to children with dyslexia.

Scaffold proteins LACK and TRACK as potential drug targets in kinetoplastid parasites: Development of inhibitors.

Parasitic diseases cause ∼ 500,000 deaths annually and remain a major challenge for therapeutic development. Using a rational design based approach, we developed peptide inhibitors with anti-parasitic activity that were derived from the sequences of parasite scaffold proteins LACK (Leishmania's receptor for activated C-kinase) and TRACK (Trypanosoma receptor for activated C-kinase). We hypothesized that sequences in LACK and TRACK that are conserved in the parasites, but not in the mammalian ortholog, RACK (Receptor for activated C-kinase), may be interaction sites for signaling proteins that are critical for the parasites' viability. One of these peptides exhibited leishmanicidal and trypanocidal activity in culture. Moreover, in infected mice, this peptide was also effective in reducing parasitemia and increasing survival without toxic effects. The identified peptide is a promising new anti-parasitic drug lead, as its unique features may limit toxicity and drug-resistance, thus overcoming central limitations of most anti-parasitic drugs.

Mercury concentrations in surface water and harvested waterfowl from the prairie pothole region of Saskatchewan.

Mercury cycling in prairie ecosystems is poorly understood. We examined methylmercury (MeHg) concentrations in whole water from 49 diverse prairie wetlands and lakes in Saskatchewan. We also determined total Hg (THg) concentrations in waterfowl harvested by hunters for consumption. Average whole water MeHg concentrations ranged from 0.02 to over 4 ng L(-1) and were higher in water from wetland ponds compared to those in lakes. High MeHg concentrations in prairie wetlands present the possibility of increased Hg concentrations in biota inhabiting these and other similar systems. We therefore measured THg in 72 birds representing 13 species of waterfowl that commonly use prairie aquatic habitats. A large range in THg concentrations was observed among individual birds, with values ranging from below the detection limit to over 435 ng g(-1). When waterfowl were classified according to diet, we observed clear evidence of THg biomagnification with increasing proportion of animal prey consumed. THg concentrations in waterfowl collected by hunters did not exceed consumption guidelines of 0.5 mg kg(-1) developed for fish. This is the first study that has reported MeHg concentrations in water from the prairie pothole region of southern Saskatchewan.