Non-linguistic learning and aphasia: evidence from a paired associate and feedback-based task

The effect of feedback timing on category learning and feedback processing in younger and older adults

Introduction

Corrective feedback can be received immediately after an action or with a temporal delay. Neuroimaging studies suggest that immediate and delayed feedback are processed by the striatum and medial temporal lobes (MTL), respectively. Age-related changes in the striatum and MTL may influence the efficiency of feedback-based learning in older adults. The current study leverages event-related potentials (ERPs) to evaluate age-related differences in immediate and delayed feedback processing and consequences for learning. The feedback-related negativity (FRN) captures activity in the frontostriatal circuit while the N170 is hypothesized to reflect MTL activation.

Methods

18 younger (Myears  = 24.4) and 20 older (Myears  = 65.5) adults completed learning tasks with immediate and delayed feedback. For each group, learning outcomes and ERP magnitudes were evaluated across timing conditions.

Results

Younger adults learned better than older adults in the immediate timing condition. This performance difference was associated with a typical FRN signature in younger but not older adults. For older adults, impaired processing of immediate feedback in the striatum may have negatively impacted learning. Conversely, learning was comparable across groups when feedback was delayed. For both groups, delayed feedback was associated with a larger magnitude N170 relative to immediate feedback, suggesting greater MTL activation.

Discussion and conclusion

Delaying feedback may increase MTL involvement and, for older adults, improve category learning. Age-related neural changes may differentially affect MTL- and striatal-dependent learning. Future research can evaluate the locus of age-related learning differences and how feedback can be manipulated to optimize learning across the lifespan.

Verb Tense Production in People With Nonfluent Aphasia Across Different Discourse Elicitation Tasks

PURPOSE

Verb tense production is known to be impaired in people with nonfluent aphasia. Selective past tense impairment in this population has been reported, but results are inconsistent and lacking at the discourse level. In addition, language production can be affected by discourse elicitation tasks depending on the cognitive linguistic demands and instructions unique to each task. There is limited evidence regarding whether verb tense production in people with nonfluent aphasia is impacted by discourse task demands. Understanding this potential impact is important for clinicians and researchers who are interested in assessing and then identifying effective clinical goals for this population. Therefore, this study aimed to investigate the trends of verb tense production across various discourse elicitation tasks in people with nonfluent aphasia compared to people without aphasia.

METHOD

Language samples for 23 people with nonfluent aphasia and 27 people without aphasia were obtained for six discourse tasks from the AphasiaBank database. We calculated ratios of past tense, present tense, future tense, imperative, and unknown verb types to compare which tense was used most frequently within and across the tasks and groups.

RESULTS AND CONCLUSIONS

Our findings revealed evidence of verb tense production deficits and a selective past tense impairment in people with nonfluent aphasia. Discourse task effects were shown for people without aphasia but were scarce in people with nonfluent aphasia. This finding could be explained by an overall reduction of verb production and overreliance on present tense production in nonfluent aphasia. These results suggest the potential methodological implications of using different discourse tasks to evaluate verb tense production in people with nonfluent aphasia. Future studies need to evaluate discourse task effects on other aspects of verb production (e.g., moods) and specific task factors (e.g., presence or absence of visual stimulus).

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.25146242.

Early within therapy naming probes as a clinically-feasible predictor of anomia treatment response

This study investigated the relationship between early within-therapy probe naming performance and anomia therapy outcomes in individuals with aphasia. Thirty-four adults with chronic, post-stroke aphasia participated in the Aphasia Language Impairment and Functioning Therapy (Aphasia LIFT) programme, comprised of 48 h of comprehensive aphasia therapy. Sets of 30 treated and 30 untreated items identified at baseline were probed during impairment therapy which targeted word retrieval using a combined semantic feature analysis and phonological component analysis approach. Multiple regression models were computed to determine the relationship between baseline language and demographic variables, early within-therapy probe naming performance (measured after 3 h of impairment therapy) and anomia treatment outcomes. Early within-therapy probe naming performance emerged as the strongest predictor of anomia therapy gains at post-therapy and at 1-month follow-up. These findings have important clinical implications, as they suggest that an individual's performance after a brief period of anomia therapy may predict response to intervention. As such, early within-therapy probe naming may provide a quick and accessible tool for clinicians to identify potential response to anomia treatment.

The effects of adding attention training to naming treatment for individuals with aphasia

AIM

Given the ever-increasing evidence for the co-occurrence of attention impairments and language disorders in chronic aphasia, this study aimed to compare the effects of two naming treatment programs, one with and one without attention training components, on the naming performance of participants with aphasia.

MATERIALS AND METHODS

This was a single-subject crossover study in which six people with chronic aphasia and different degrees of naming and attention impairments participated. Two treatment programs were implemented for each participant, with the sequence of the treatments with crossover design. Each program consisted of 12 treatment sessions plus pre- and post-treatment assessment sessions (15 weeks for each participant). The visual analysis and WEighted STatistics methods were employed for data analysis.

RESULTS

Based on visual analysis, both treatments improved in comparison to the baseline phase. Statistical analysis revealed that the number of participants with significant naming improvement following combined program (5 participants) was larger than the number of participants showing improvement following completion of the single, program.

CONCLUSION

Although integrating attention training into a conventional treatment for anomia can increase the effect of treatment on naming ability, more studies are required to clarify the role of attention in remediating naming impairments in aphasia.

Insights gained over 60 years on factors shaping post-stroke aphasia recovery: A commentary on Vignolo (1964)

Aphasia is an acquired language disorder resulting from brain injury, including strokes which is the most common etiology, neurodegenerative diseases, tumors, traumatic brain injury, and resective surgery. Aphasia affects a significant portion of stroke survivors, with approximately one third experiencing its debilitating effects in the long term. Despite its challenges, there is growing evidence that recovery from aphasia is possible, even in the chronic phase of stroke. Sixty years ago, Vignolo (1964) outlined the primary challenges confronted by researchers in this field. These challenges encompassed the absence of an objective evaluation of language difficulties, the scarcity of evidence regarding spontaneous aphasia recovery, and the presence of numerous variables that could potentially influence the process of aphasia recovery. In this paper, we discuss the remarkable progress that has been made in the assessment of language and communication in aphasia as well as in understanding the factors influencing post-stroke aphasia recovery.

An electrophysiological and behavioral investigation of feedback-based learning in aphasia

Introduction

Feedback is a fundamental aspect of aphasia treatments. However, learning from feedback is a cognitively demanding process. At the most basic level, individuals must detect feedback and extract outcome-related information (i.e., feedback processing). Neuroanatomical and neuropsychological differences associated with post-stroke aphasia may influence feedback processing and potentially how people with aphasia (PWA) respond to feedback-based treatments. To better understand how post-stroke aphasia affects feedback-based learning, the current study leverages event-related potentials (ERPs) to (1) characterize the relationship between feedback processing and learning, (2) identify cognitive skills that are associated with feedback processing, and (3) identify behavioural correlates of feedback-based learning in PWA.

Methods

Seventeen PWA completed a feedback-based novel word learning task. Feedback processing was measured using the feedback-related negativity (FRN), an ERP hypothesized to reflect the detection and evaluation of outcomes communicated via feedback. Individuals also completed neuropsychological assessments of language (phonological processing, verbal short-term memory) and executive functioning.

Results

PWA elicited an FRN that was sensitive to feedback valence. The magnitude of the FRN was not associated with novel word learning but was strongly correlated with performance on another feedback-based task, the Berg Card Sort. Cognitive variables (information updating, selective attention) but not language variables were associated with novel word learning.

Discussion & Conclusion

For PWA, feedback processing may be associated with learning in some but not all feedback-based contexts. These findings may inform future research in determining which variables moderate the relationship between feedback processing and learning with the long-term goal of identifying how feedback can be modified to support successful learning during aphasia rehabilitation.

Mapping spoken language and cognitive deficits in post-stroke aphasia

Aphasia is an acquired disorder caused by damage, most commonly due to stroke, to brain regions involved in speech and language. While language impairment is the defining symptom of aphasia, the co-occurrence of non-language cognitive deficits and their importance in predicting rehabilitation and recovery outcomes is well documented. However, people with aphasia (PWA) are rarely tested on higher-order cognitive functions, making it difficult for studies to associate these functions with a consistent lesion correlate. Broca's area is a particular brain region of interest that has long been implicated in speech and language production. Contrary to classic models of speech and language, cumulative evidence shows that Broca's area and surrounding regions in the left inferior frontal cortex (LIFC) are involved in, but not specific to, speech production. In this study we aimed to explore the brain-behaviour relationships between tests of cognitive skill and language abilities in thirty-six adults with long-term speech production deficits caused by post-stroke aphasia. Our findings suggest that non-linguistic cognitive functions, namely executive functions and verbal working memory, explain more of the behavioural variance in PWA than classical language models imply. Additionally, lesions to the LIFC, including Broca's area, were associated with non-linguistic executive (dys)function, suggesting that lesions to this area are associated with non-language-specific higher-order cognitive deficits in aphasia. Whether executive (dys)function - and its neural correlate in Broca's area - contributes directly to PWA's language production deficits or simply co-occurs with it, adding to communication difficulties, remains unclear. These findings support contemporary models of speech production that place language processing within the context of domain-general perception, action and conceptual knowledge. An understanding of the covariance between language and non-language deficits and their underlying neural correlates will inform better targeted aphasia treatment and outcomes.

Targeted neurorehabilitation strategies in post-stroke aphasia

BACKGROUND

Aphasia is a debilitating language impairment, affecting millions of people worldwide. About 40% of stroke survivors develop chronic aphasia, resulting in life-long disability.

OBJECTIVE

This review examines extrinsic and intrinsic neuromodulation techniques, aimed at enhancing the effects of speech and language therapies in stroke survivors with aphasia.

METHODS

We discuss the available evidence supporting the use of transcranial direct current stimulation (tDCS), repetitive transcranial magnetic stimulation, and functional MRI (fMRI) real-time neurofeedback in aphasia rehabilitation.

RESULTS

This review systematically evaluates studies focusing on efficacy and implementation of specialized methods for post-treatment outcome optimization and transfer to functional skills. It considers stimulation target determination and various targeting approaches. The translation of neuromodulation interventions to clinical practice is explored, emphasizing generalization and functional communication. The review also covers real-time fMRI neurofeedback, discussing current evidence for efficacy and essential implementation parameters. Finally, we address future directions for neuromodulation research in aphasia.

CONCLUSIONS

This comprehensive review aims to serve as a resource for a broad audience of researchers and clinicians interested in incorporating neuromodulation for advancing aphasia care.

How Much Attention Do We Pay to Attention Deficits in Poststroke Aphasia?

Although language deficits are the primary area of weakness, people with poststroke aphasia often experience challenges with nonlinguistic cognitive skills, including attention processing. The purpose of this review is to synthesize the evidence for the relationship between attention deficits and language deficits in people with poststroke aphasia. Three different types of studies are reviewed: (1) studies exploring whether people with poststroke aphasia exhibit concomitant attention and language deficits, (2) studies explicitly exploring the relationship between attention and language deficits in people with poststroke aphasia, and (3) either language or attention (or both) treatment studies exploring whether treatment gains in one domain generalize to the other. In the last section, we briefly review research evidence for the neural basis of the attention-language relationship in aphasia.

The role of the hippocampus in statistical learning and language recovery in persons with post stroke aphasia

Although several studies have aimed for accurate predictions of language recovery in post stroke aphasia, individual language outcomes remain hard to predict. Large-scale prediction models are built using data from patients mainly in the chronic phase after stroke, although it is clinically more relevant to consider data from the acute phase. Previous research has mainly focused on deficits, i.e., behavioral deficits or specific brain damage, rather than compensatory mechanisms, i.e., intact cognitive skills or undamaged brain regions. One such unexplored brain region that might support language (re)learning in aphasia is the hippocampus, a region that has commonly been associated with an individual's learning potential, including statistical learning. This refers to a set of mechanisms upon which we rely heavily in daily life to learn a range of regularities across cognitive domains. Against this background, thirty-three patients with aphasia (22 males and 11 females, M = 69.76 years, SD = 10.57 years) were followed for 1 year in the acute (1-2 weeks), subacute (3-6 months) and chronic phase (9-12 months) post stroke. We evaluated the unique predictive value of early structural hippocampal measures for short-term and long-term language outcomes (measured by the ANELT). In addition, we investigated whether statistical learning abilities were intact in patients with aphasia using three different tasks: an auditory-linguistic and visual task based on the computation of transitional probabilities and a visuomotor serial reaction time task. Finally, we examined the association of individuals' statistical learning potential with acute measures of hippocampal gray and white matter. Using Bayesian statistics, we found moderate evidence for the contribution of left hippocampal gray matter in the acute phase to the prediction of long-term language outcomes, over and above information on the lesion and the initial language deficit (measured by the ScreeLing). Non-linguistic statistical learning in patients with aphasia, measured in the subacute phase, was intact at the group level compared to 23 healthy older controls (8 males and 15 females, M = 74.09 years, SD = 6.76 years). Visuomotor statistical learning correlated with acute hippocampal gray and white matter. These findings reveal that particularly left hippocampal gray matter in the acute phase is a potential marker of language recovery after stroke, possibly through its statistical learning ability.

Language learning in aphasia: A narrative review and critical analysis of the literature with implications for language therapy

People with aphasia (PWA) present with language deficits including word retrieval difficulties after brain damage. Language learning is an essential life-long human capacity that may support treatment-induced language recovery after brain insult. This prospect has motivated a growing interest in the study of language learning in PWA during the last few decades. Here, we critically review the current literature on language learning ability in aphasia. The existing studies in this area indicate that (i) language learning can remain functional in some PWA, (ii) inter-individual variability in learning performance is large in PWA, (iii) language processing, short-term memory and lesion site are associated with learning ability, (iv) preliminary evidence suggests a relationship between learning ability and treatment outcomes in this population. Based on the reviewed evidence, we propose a potential account for the interplay between language and memory/learning systems to explain spared/impaired language learning and its relationship to language therapy in PWA. Finally, we indicate potential avenues for future research that may promote more cross-talk between cognitive neuroscience and aphasia rehabilitation.

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.

Understanding, facilitating and predicting aphasia recovery after rehabilitation

Purpose: This paper reviews several studies whose aim was to understand the nature of language recovery in chronic aphasia and identify predictors of how people may recover their language functions after a brain injury.Method: Several studies that mostly draw from data collected within the Centre for Neurobiology of Language Recovery were reviewed and categorised in four aspects of language impairment and recovery in aphasia: (a) neural markers for language impairment and recovery, (b) language and cognitive markers for language impairment and recovery, (c) effective treatments and (d) predictive modelling of treatment-induced rehabilitation.Result: Language impairment and recovery in stroke-induced aphasia is multi-factorial, including patient-specific and treatment-specific factors. A combination of these factors may help us predict treatment responsiveness even before treatment begins.Conclusion: Continued work on this topic will lead to a better understanding of the mechanisms that underly language impairment and treatment-induced recovery in aphasia, and, consequently, use this information to predict each person's recovery profile trajectory and provide optimal prescriptions regarding the type and dosage of treatment.

Strategy Development and Feedback Processing During Complex Category Learning

In this study, 38 young adults participated in a probabilistic A/B prototype category learning task under observational and feedback-based conditions. The study compared learning success (testing accuracy) and strategy use (multi-cue vs. single feature vs. random pattern) between training conditions. The feedback-related negativity (FRN) and P3a event related potentials were measured to explore the relationships between feedback processing and strategy use under a probabilistic paradigm. A greater number of participants were found to utilize an optimal, multi-cue strategy following feedback-based training than observational training, adding to the body of research suggesting that feedback can influence learning approach. There was a significant interaction between training phase and strategy on FRN amplitude. Specifically, participants who used a strategy in which category membership was determined by a single feature (single feature strategy) exhibited a significant decrease in FRN amplitude from early training to late training, perhaps due to reduced utilization of feedback or reduced prediction error. There were no significant main or interaction effects between valence, training phase, or strategy on P3a amplitude. Findings are consistent with prior research suggesting that learners vary in their approach to learning and that training method influences learning. Findings also suggest that measures of feedback processing during probabilistic category learning may reflect changes in feedback utilization and may further illuminate differences among individual learners.

Translation and Cross-cultural Adaptation of the Aphasia Check List in Persian Speakers With Aphasia

Introduction:

The Aphasia Check List (ACL) is a comprehensive, time-saving tool for language evaluation in aphasia, including a cognitive assessment part. This cross-sectional study aimed to translate ACL into Persian and analyze the psychometric features of the translated version. The original version of the ACL was translated and adapted from German; its psychometric features were then determined.

Methods:

Twenty People With Aphasia (PWA) and 50 age- and education-matched, cognitively healthy controls participated in this research. Possible floor and ceiling effects, discriminant validity, test-retest reliability, and internal consistency of the test were analyzed in addition to the evaluation of internal correlations between the test parts (language & cognition).

Results:

Regarding the performance of PWAs in the language section and the cognitive subtests assessing attention, memory, and reasoning, there were no floor and ceiling effects. Adequate discriminant validities for the language section of the test [i.e., total score: (Mann-Whitney U= 6.000, P<0.001); diagnostic subtests scores: (Mann-Whitney U= 3.000, P<0.001), and each subtest individually. Besides, the attention subtest of the cognition section (Mann-Whitney U= 16.500, P<0.001) was also observed. There was no difference between the control and patient groups in the subtests of memory (Mann-Whitney U= 497.500, P=0.973) and reasoning (Mann-Whitney U= 3.000, P= 308). The test-retest reliability was acceptable in all subtests (ICC agreement= 0.573–0.984). The ACL-P suggested appropriate internal consistency (Cronbach’s alpha coefficient= 0.761 for test & retest scores). There were also significant correlations between language and cognition in the control and patient groups.

Conclusion:

The ACL-P test indicated sufficient reliability and validity for the evaluation of Persian-speaking PWAs and is suggested to be used in studies on this population.

The Application of Lexical Retrieval Training in Tablet-Based Speech-Language Intervention

In the setting of shortened hospitalization periods, periods of confinement and social isolation, limited resources, and accessibility, technology can be leveraged to enhance opportunities for rehabilitative care (1). In the current manuscript, we focus on the use of tablet-based rehabilitation for individuals with aphasia, a language disorder that frequently arises post-stroke. Aphasia treatment that targets naming through effortful and errorful instances of lexical retrieval, where corrective feedback is generated on every trial, may enhance retention and generalizability of gains (2, 3). This pilot evaluation explored how six individuals with aphasia interacted with a tablet-based therapy application that targeted lexical retrieval. Participants with aphasia either (1) autonomously engaged with the therapy tasks or (2) received systematic encouragement to effortfully retrieve words. Behaviors of response latency and cue use were examined to gain insights into the behavioral patterns of both groups, as well as analyses of task accuracy and outcomes on standardized cognitive-linguistic assessments. Despite some variability, initial observations suggest that participants who received systematic training refrained from using cues to complete tasks and spent longer on each trial, which ultimately co-occurred with increased independent engagement with therapy and improved standardized outcomes. Preliminary results present an alternative means of leveraging technology to implement best-practice recommendations in the context of aphasia telerehabilitation.

Decision Making by People With Aphasia: A Comparison of Linguistic and Nonlinguistic Measures

Purpose Decision making involves multiple cognitive and linguistic processes. The extent to which these processes are involved depends, in part, on the conditions under which decision making is assessed. Because people with aphasia (PWA) have impaired language abilities and may also present with cognitive deficits, they may have difficulty during decision-making tasks. Yet little research exists on the decision-making abilities of PWA. Thus, the purposes of this study were to investigate the performance of PWA on linguistic and nonlinguistic decision-making measures and to explore the relationship between decision making and cognitive test performance. Method A quasi-experimental design was used to compare the performance of PWA (n = 16) and age- and education-matched control participants (n = 16) on three decision-making tasks: Making a Decision subtest from the Functional Assessment of Verbal Reasoning and Executive Strategies (linguistic decision-making task), Iowa Gambling Task (nonlinguistic decision-making task with ambiguity), and Game of Dice Task (nonlinguistic decision-making task without ambiguity). Participants also completed assessments of language, working memory, and executive functions. Scores on the three decision-making tasks were compared between groups, and cognitive influences on decision-making performance were examined using correlation analyses. Results PWA differed significantly from control participants on linguistic decision making, particularly when required to verbalize their rationale for making their decision. PWA and control participants did not differ significantly on measures of nonlinguistic decision making. Performance on multiple cognitive measures was correlated with performance on the linguistic reasoning task, as well as one of the nonlinguistic tasks (Game of Dice Task). Conclusions Decision-making tasks that are heavily dependent on language, such as those used in capacity assessments, may disadvantage PWA. Assessments of decision-making capacity should include communication supports for people with acquired communication disorders; further investigation in the areas of decision making and aphasia is needed.

A Review of the Application of Distributed Practice Principles to Naming Treatment in Aphasia

It is uncontroversial in psychological research that different schedules of practice, which govern the distribution of practice over time, can promote radically different outcomes in terms of gains in performance and the durability of learning. In contrast, in speech-language treatment research, there is a critical need for well-controlled studies examining the impact of the distribution of treatment on efficacy (for reviews, see Cherney, 2012; Warren, Fey, & Yoder, 2007). In this paper, we enumerate key findings from psychological research on learning and memory regarding how different schedules of practice differentially confer durable learning. We review existing studies of aphasia treatment with a focus on naming impairment that have examined how the distribution of practice affects treatment efficacy. We close by discussing potential productive lines of research to elaborate the clinical applicability of distributed practice principles to language treatment.

Systematic review of subjective memory measures to inform assessing memory limitations after stroke and stroke-related aphasia

AIM

Primary aims of this systematic review were to: (1) identify the range of subjective memory measures used in the stroke and stroke-related aphasia literature and (2) critically appraise their psychometric properties as well as (3) the methodological qualities of studies that included them, (4) investigate whether such measures provide an accurate reflection of memory impairments (i.e., in comparison to norms from age-matched, neurotypical participants), (5) document the representation of individuals with stroke-related aphasia, and (6) examine the extent to which subjective memory measures correlate with objective memory measures.

METHODS

Systematic review of the literature from 1970 to June 2019 using a comprehensive range of relevant search terms in EMBASE, Medline, PsychINFO, SCOPUS, and Web of Science. Eligibility criteria were for studies to include adults who had suffered of clinical stroke, to report a subjective memory measure that was completed by the stroke survivors, to be reported in a peer-reviewed journal, and to be published in English or Dutch. Quality appraisal was carried out for the included studies as well as the subjective memory measures they employed.

RESULTS

A total of 7,077 titles or abstracts were screened, with 41 studies included in the quantitative and qualitative synthesis. Twenty-six subjective memory measures were used in the included studies. The critical appraisal of their psychometric properties and the methodological quality of the included studies revealed significant shortcomings; for example, neurotypical participants were included in only 14 of the 41 studies. When statistical comparisons were made, different outcomes arose. Only eight studies statistically compared subjective with objective memory measures.

CONCLUSIONS

This literature domain currently provides an unclear picture as to how memory limitations affect participation in stroke and stroke-related aphasia.IMPLICATIONS FOR REHABILITATIONA broad range of subjective memory measures have been used to determine stroke survivors' perceptions of their everyday memory issues.Because of psychometric weaknesses such as inadequate reliability and cross-cultural validity among subjective memory measures, there remains a need to carefully review a given measure's properties to determine if it is appropriate for use with a given stroke survivor.Stroke survivors with aphasia have been infrequently included or inadequately described in studies of subjective memory measures, and thus how these individuals perceive their everyday memory abilities requires further investigation.Although the relationship between subjective and objective memory measures has been infrequently investigated by stroke researchers, both types of measures should be considered as they likely offer complementary rather than redundant information about stroke survivors' memory abilities.

Sentence Processing in Aphasia: An Examination of Material-Specific and General Cognitive Factors

The purpose of this study was to characterize further the nature of sentence processing deficits in acquired aphasia. Adults with aphasia and age-and education-matched adults with no brain damage completed a battery of formal cognitive-linguistic tests and an experimental sentence judgment task, which was performed alone and during focused attention and divided attention or dual-task conditions. The specific aims were to determine whether (a) increased extra-linguistic cognitive demands (i.e., focused and divided conditions) differentially affected the sentence judgement performances of the aphasic and control groups, (b) increased extra- linguistic cognitive demands interact with stimulus parameters (i.e., syntactic complexity, number of propositions) known to influence sentence processing, and (c) syntactic- or material specific resource limitations (e.g., sentence judgment in isolation), general cognitive abilities (e.g., short-term and working memory test scores), or both share a significant relationship with dual-task outcomes. Accuracy, grammatical sensitivity, and reaction time findings were consistent with resource models of aphasia and processing accounts of aphasic syntactic limitations, underscoring the theoretical and clinical importance of acknowledging and specifying the strength and nature of interactions between linguistic and extra-linguistic cognitive processes in not only individuals with aphasia, but also other patient and typical aging populations.

Cognitive functioning in chronic post-stroke aphasia

There is a minimal amount of knowledge regarding the cognitive abilities of people with aphasia. We evaluated the performance of individuals with chronic aphasia (AP) and control participants without aphasia (CP) with left hemisphere stroke in a battery of nonverbal cognitive tests and its relationship with aphasia severity, comprehension abilities, and speech fluency in a prospective cross-sectional study. Cognitive evaluation comprised 10 nonverbal tests. Scores were converted to age and education adjusted standard scores. Forty-eight AP and 32 CP were included. AP average scores were below normal range in three tests: Camel and Cactus Test, immediate recall of 5 Objects Test and Spatial Span. The mean test scores were significantly lower in AP than in CP, except in four tests. Aphasia severity and verbal comprehension ability correlated significantly with semantic memory, constructive abilities and attention/processing speed tests. Subjects with nonfluent aphasia had lower scores than CP in memory, executive functions and attention tests, while subjects with fluent aphasia showed lower scores in memory tests only. On average half of the individuals with aphasia exhibit results within the normal range. Nonetheless, their performance was worse than that of controls, despite the fact that many tests do not correlate with the severity of language disorder.

Cross-situational word learning in aphasia

Human learners can resolve referential ambiguity and discover the relationships between words and meanings through a cross-situational learning (CSL) strategy. Some people with aphasia (PWA) can learn word-referent pairings under referential uncertainty supported by online feedback. However, it remains unknown whether PWA can learn new words cross-situationally and if such learning ability is supported by statistical learning (SL) mechanisms. The present study examined whether PWA can learn novel word-referent mappings in a CSL task without feedback. We also studied whether CSL is related to SL in PWA and neurologically healthy individuals. We further examined whether aphasia severity, phonological processing and verbal short-term memory (STM) predict CSL in aphasia, and also whether individual differences in verbal STM modulate CSL in healthy older adults. Sixteen people with chronic aphasia underwent a CSL task that involved exposure to a series of individually ambiguous learning trials and a SL task that taps speech segmentation. Their learning ability was compared to 18 older controls and 39 young adults recruited for task validation. CSL in the aphasia group was below the older controls and young adults and took place at a slower rate. Importantly, we found a strong association between SL and CSL performance in all three groups. CSL was modulated by aphasia severity in the aphasia group, and by verbal STM capacity in the older controls. Our findings indicate that some PWA can preserve the ability to learn new word-referent associations cross-situationally. We suggest that both PWA and neurologically intact individuals may rely on SL mechanisms to achieve CSL and that verbal STM also influences CSL. These findings contribute to the ongoing debate on the cognitive mechanisms underlying this learning ability.

Cognitive performance in aphasia due to stroke: a systematic review

Aphasia persists in about one third of the patients with left hemisphere stroke, yet it is not known if it enhances the risk of dementia, beyond what results from any focal brain lesion. This lack of knowledge is mostly related to the difficulty of cognitive evaluation in people with aphasia. The development of tools aiming to assess cognitive functioning in people with aphasia could overcome this limitation. The aim of this systematic review was to evaluate the frequency and the profile of cognitive impairment in stroke patients with aphasia, to assemble existing non-verbal instruments to be used in patients with language disorders.

We conducted a systematic review, through Web of Science, Medline and PsycINFO electronic databases, of articles published between January 1995 and October 31, 2015 related to aphasia due to stroke and non-verbal neurobehavioral tests.

The electronic search identified 2487 citations. After screening 38 were included in this review. Additionally 53 articles were selected among the references of analyzed publications of which nine were included producing a total of 47 articles. The cognitive tests more frequently used in persons with aphasia are the Figures Memory Tests, Visual Memory Span, Progressive Matrices, Wisconsin Card Sorting Test and some measures of the Test of Everyday Attention, covering a reasonable range of cognitive domains. The majority of studies across cognitive domains reported lower scores for patients with aphasia compared with controls. No specific difficulties were reported regarding tests applicability.

There are several tools available to assess cognitive functions in aphasia. Although there is some variability, patients with aphasia tend to present lower scores than those with left hemisphere stroke without aphasia or healthy subjects. A consensus tool should be developed to screen or evaluate cognition and dementia in individuals with language impairment.

Implicit learning and implicit treatment outcomes in individuals with aphasia

BACKGROUND

Implicit learning is a process of learning that occurs outside of conscious awareness and may be involved in implicit, exposure-based language training. However, research shows that implicit learning abilities are variable among individuals with aphasia, and it remains unknown whether individuals who show basic implicit learning abilities also benefit from implicit language training.

AIMS

The aims of this series of experiments were to test implicit learning in individuals with agrammatic aphasia, examine the effects of a novel implicit language treatment, and investigate whether individuals with aphasia who show implicit learning ability also benefit from implicit treatment focused on passive sentence comprehension.

METHODS & PROCEDURES

Nine participants with chronic agrammatic aphasia and 21 neurologically intact participants completed a visuomotor serial reaction time test of implicit learning (Experiment 1). The participants with aphasia also completed a short-term novel implicit sentence comprehension treatment (Experiment 2) that consisted of five sessions of repeated exposure to grammatically correct passive sentences and matching photographs. Sentence comprehension was tested in multiple baseline sessions and on each day of training using a sentence-picture matching task. The relation between participants' learning patterns across experiments was also examined.

OUTCOMES & RESULTS

Individuals with agrammatic aphasia as well as neurologically intact adults demonstrated significant implicit sequence learning in the serial reaction time task. However, the participants with aphasia did not show concomitant improvement in sentence comprehension as a result of the implicit treatment protocol.

CONCLUSIONS

This study suggests that individuals with agrammatic aphasia demonstrate implicit learning ability; however, this ability does not necessarily promote successful outcomes in treatment that is based solely on implicit training methods.

Treatment of verb anomia in aphasia: efficacy of self-administered therapy using a smart tablet

Aphasia is a chronic condition that usually requires long-term rehabilitation. However, even if many effective treatments can be offered to patients and families, speech therapy services for individuals with aphasia often remain limited because of logistical and financial considerations, especially more than 6 months after stroke. Therefore, the need to develop tools to maximize rehabilitation potential is unquestionable. The aim of this study was to test the efficacy of a self-administered treatment delivered with a smart tablet to improve written verb naming skills in CP, a 63-year-old woman with chronic aphasia. An ABA multiple baseline design was used to compare CP's performance in verb naming on three equivalent lists of stimuli trained with a hierarchy of cues, trained with no cues, and not trained. Results suggest that graphemic cueing therapy, done four times a week for 3 weeks, led to better written verb naming compared to baseline and to the untrained list. Moreover, generalization of the effects of treatment was observed in verb production, assessed with a noun-to-verb production task. Results of this study suggest that self-administered training with a smart tablet is effective in improving naming skills in chronic aphasia. Future studies are needed to confirm the effectiveness of new technologies in self-administered treatment of acquired language deficits.

An Examination of Strategy Implementation During Abstract Nonlinguistic Category Learning in Aphasia

PURPOSE

Our purpose was to study strategy use during nonlinguistic category learning in aphasia.

METHOD

Twelve control participants without aphasia and 53 participants with aphasia (PWA) completed a computerized feedback-based category learning task consisting of training and testing phases. Accuracy rates of categorization in testing phases were calculated. To evaluate strategy use, strategy analyses were conducted over training and testing phases. Participant data were compared with model data that simulated complex multi-cue, single feature, and random pattern strategies. Learning success and strategy use were evaluated within the context of standardized cognitive-linguistic assessments.

RESULTS

Categorization accuracy was higher among control participants than among PWA. The majority of control participants implemented suboptimal or optimal multi-cue and single-feature strategies by testing phases of the experiment. In contrast, a large subgroup of PWA implemented random patterns, or no strategy, during both training and testing phases of the experiment.

CONCLUSIONS

Person-to-person variability arises not only in category learning ability but also in the strategies implemented to complete category learning tasks. PWA less frequently developed effective strategies during category learning tasks than control participants. Certain PWA may have impairments of strategy development or feedback processing not captured by language and currently probed cognitive abilities.

The contrast between cueing and/or observation in therapy for verb retrieval in post-stroke aphasia

BACKGROUND

Studies measuring treatment efficacy for post-stroke verb anomia are scarce. These studies mainly assessed the efficacy of three strategies: semantic, phonological and sensorimotor. Following these previous treatments, the performance of most participants improved on treated verbs, while improvement on untreated stimuli and tasks was inconsistent.

AIMS

This study aimed to measure the effectiveness of a semantic-phonological strategy and a sensorimotor strategy for verb anomia in post-stroke aphasia.

METHODS

A multiple baseline single-subject experimental study was conducted with two participants (9-37 years post-stroke). Four phases were completed: (1) background assessment, (2) baselines, (3) therapy, and (4) follow-up. Three equivalent lists of verbs were created for each participant and two of them were trained with a different strategy: action observation+semantic-phonological cues, action observation alone. The stimuli of the third list (control list) were not treated.

RESULTS

The semantic-phonological cueing strategy led to a significant improvement. No improvement was observed after action observation. No generalization to untreated verbs was found.

CONCLUSIONS

Verb naming can be enhanced by semantic/phonological cueing. In addition, other studies (clinical, neuroimaging, etc.) are needed to document the effect of action observation for the treatment of verb anomia.

LEARNING OUTCOMES

The reader will be able to (1) describe semantic-phonological therapies used in post-stroke verb anomia, (2) describe sensorimotor therapies used in post-stroke verb anomia, and (3) identify factors contributing to the efficacy of therapies to improve action naming in aphasia.

Characteristics of Cognitive Impairment in Patients With Post-stroke Aphasia

Objective

To analyze cognitive functions of post-stroke aphasia patients compared to patients having right hemispheric stroke and left hemispheric lesions without aphasia, and to look for a relationship between cognitive deficits and aphasia severity.

Methods

Thirty-six patients with right hemispheric stroke (group 1), 32 with left hemispheric lesion without aphasia (group 2), and 26 left hemispheric stroke patients with aphasia (group 3) completed a set of tests in the computerized neurocognitive function batteries for attention, executive function and intelligence and Korean version of Western Aphasia Battery. Data analyses explored cognitive characteristics among the three groups and the correlation between cognitive deficits and aphasia severity.

Results

Right hemispheric and left hemispheric stroke patients without aphasia showed similar findings except for digit span forward test. Cognitive tests for working memory and sustained attention were significantly impaired in the aphasic patients, but intelligence was shown to be similar in the three groups. Significant correlation between cognitive deficit and aphasia severity was only shown in some attention tests.

Conclusion

Cognitive deficits may be accompanied with post-stroke aphasia and there are possible associations between language and cognitive measures. Therefore, detection and treatment towards coexisting cognitive impairment may be necessary for efficient aphasia treatment.

Nonlinguistic learning in individuals with aphasia: effects of training method and stimulus characteristics

PURPOSE

The purpose of the current study was to explore nonlinguistic learning ability in individuals with aphasia, examining the impact of stimulus typicality and feedback on success with learning.

METHOD

Eighteen individuals with aphasia and 8 nonaphasic controls participated in this study. All participants completed 4 computerized, nonlinguistic category-learning tasks. Learning ability was probed under 2 methods of instruction: feedback-based (FB) and paired-associate (PA). The impact of task complexity on learning ability was also examined, comparing 2 stimulus conditions: typical and atypical. Performance was compared between groups and across conditions.

RESULTS

The controls were able to successfully learn categories under all conditions. For the individuals with aphasia, 2 patterns of performance arose: One subgroup of individuals was able to maintain learning across task manipulations and conditions; the other subgroup demonstrated a sensitivity to task complexity, learning successfully only in the typical training conditions.

CONCLUSION

Results support the hypothesis that impairments of general learning are present in individuals with aphasia. Some individuals demonstrated the ability to extract category information under complex training conditions; others learned only under conditions that were simplified and that emphasized salient category features. Overall, the typical training condition facilitated learning for all of the participants. Findings have implications for treatment, which are discussed.