Predicting Outcomes of Language Rehabilitation: Prognostic Factors for Immediate and Long-Term Outcomes After Aphasia Therapy.

BACKGROUND: Aphasia therapy is an effective approach to improve language function in chronic aphasia. However, it remains unclear what prognostic factors facilitate therapy response at the individual level. Here, we utilized data from the POLAR (Predicting Outcomes of Language Rehabilitation in Aphasia) trial to (a) determine therapy-induced change in confrontation naming and long-term maintenance of naming gains and (b) examine the extent to which aphasia severity, age, education, time postonset, and cognitive reserve predict naming gains at 1 week, 1 month, and 6 months posttherapy. METHOD: A total of 107 participants with chronic (≥ 12 months poststroke) aphasia underwent extensive case history, cognitive-linguistic testing, and a neuroimaging workup prior to receiving 6 weeks of impairment-based language therapy. Therapy-induced change in naming performance (measured as raw change on the 175-item Philadelphia Naming Test [PNT]) was assessed 1 week after therapy and at follow-up time points 1 month and 6 months after therapy completion. Change in naming performance over time was evaluated using paired t tests, and linear mixed-effects models were constructed to examine the association between prognostic factors and therapy outcomes. RESULTS: Naming performance was improved by 5.9 PNT items (Cohen's d = 0.56, p < .001) 1 week after therapy and by 6.4 (d = 0.66, p < .001) and 7.5 (d = 0.65, p < .001) PNT items at 1 month and 6 months after therapy completion, respectively. Aphasia severity emerged as the strongest predictor of naming improvement recovery across time points; mild (ß = 5.85-9.02) and moderate (ß = 9.65-11.54) impairment predicted better recovery than severe (ß = 1.31-3.37) and very severe (ß = 0.20-0.32) aphasia. Age was an emergent prognostic factor for recovery 1 month (ß = -0.14) and 6 months (ß = -0.20) after therapy, and time postonset (ß = -0.05) was associated with retention of naming gains at 6 months posttherapy. CONCLUSIONS: These results suggest that therapy-induced naming improvement is predictable based on several easily measurable prognostic factors. Broadly speaking, these results suggest that prognostication procedures in aphasia therapy can be improved and indicate that personalization of therapy is a realistic goal in the near future. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.22141829.

The Severity-Calibrated Aphasia Naming Test.

PURPOSE: We present a 20-item naming test, the Severity-Calibrated Aphasia Naming Test (SCANT), that can serve as a proxy measure for an aphasia severity scale that is derived from a thorough test battery of connected speech production, single-word production, speech repetition, and auditory verbal comprehension. METHOD: We use lasso regression and cross-validation to identify an optimal subset from a set of 174 pictures to be named for prediction of aphasia severity, based on data from 200 participants with left-hemisphere stroke who were quasirandomly selected to represent the full impairment scale. Data from 20 healthy controls (i.e., participant caretakers/spouses) were also analyzed. We examine interrater reliability, test-retest reliability, sensitivity and specificity to the presence of aphasia, sensitivity to therapy gains, and external validity (i.e., correlation with aphasia severity measures) for the SCANT. RESULTS: The SCANT has extremely high interrater reliability, and it is sensitive and specific to the presence of aphasia. We demonstrate the superiority of predictions based on the SCANT over those based on the full set of naming items. We estimate a 15% reduction in power when using the SCANT score versus the full test battery's aphasia severity score as an outcome measure; for example, to maintain the same power to detect a significant group average change in aphasia severity, a study with 25 participants using the full test battery to measure treatment effectiveness would require 30 participants if the SCANT were to be used as the testing instrument instead. CONCLUSION: We provide a linear model to convert SCANT scores to aphasia severity scores, and we identify a change score cutoff of four SCANT items to obtain a high degree of confidence based on test-retest SCANT data and the modeled relation between SCANT and aphasia severity scores. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.21476871.

Demystifying the Complexity of Aphasia Treatment: Application of the Rehabilitation Treatment Specification Systemx.

A considerable body of research supports the use of behavioral communication treatment as the standard of care for aphasia. In spite of robust progress in clinical aphasiology, many questions regarding optimal care remain unanswered. One of the major challenges to progress in the field is the lack of a common framework to adequately describe individual treatments, which, if available, would allow comparisons across studies as well as improved communication among researchers, clinicians, and other stakeholders. Here, we describe how aphasia treatment approaches can be systematically characterized using the Rehabilitation Treatment Specification System (RTSS). At the core of the RTSS is a tripartite structure that focuses on targets (the behavior that is expected to change as a result of treatment), ingredients (what a clinician does to affect change in the target), and mechanism(s) of action (why a given treatment works by linking the ingredients to the target). Three separate articles in the current issue specifically describe how the RTSS can be used to describe different kinds of aphasia treatment approaches: functional approaches, cognitive-linguistic approaches, and biological approaches. It is our hope that the application of the RTSS in clinical aphasiology will improve communication in published studies, grant proposals, and in the clinical care of persons with aphasia.

Defining the Neurobiological Mechanisms of Action in Aphasia Therapies: Applying the Rehabilitation Treatment Specification System Framework to Research and Practice in Aphasia.

The Rehabilitation Treatment Specification System (RTSS) was developed as a systematic way to describe rehabilitation treatments for the purpose of both research and practice. The RTSS groups treatments by type and describes them by 3 elements: the treatment (1) ingredients and (2) the mechanisms of action that yield changes in the (3) target behavior. Adopting the RTSS has the potential to improve consistency in research, allowing for better cross-study comparisons to strengthen the body of research supporting various treatments. Because it is still early in its development, the RTSS has not yet been widely implemented across different rehabilitation disciplines. In particular, aphasia recovery is one area of rehabilitation that could benefit from a unifying framework. Accordingly, this article is part of a series where we illustrate how the RTSS can be applied to aphasia treatment and research. This article more specifically focuses on examining the neurobiological mechanisms of action associated with experimental aphasia therapies, including brain stimulation and pharmacologic intervention, as well as more traditional behavioral therapy. Key elements of the RTSS are described, and 4 example studies are used to illustrate how the RTSS can be implemented. The benefits of a unifying framework for the future of aphasia treatment research and practice are discussed.

Beyond Percent Correct: Measuring Change in Individual Picture Naming Ability.

PURPOSE: Meaningful changes in picture naming responses may be obscured when measuring accuracy instead of quality. A statistic that incorporates information about the severity and nature of impairments may be more sensitive to the effects of treatment. METHOD: We analyzed data from repeated administrations of a naming test to 72 participants with stroke aphasia in a clinical trial for anomia therapy. Participants were divided into two groups for analysis to demonstrate replicability. We assessed reliability among response type scores from five raters. We then derived four summary statistics of naming ability and their changes over time for each participant: (a) the standard accuracy measure, (b) an accuracy measure adjusted for item difficulty, (c) an accuracy measure adjusted for item difficulty for specific response types, and (d) a distance measure adjusted for item difficulty for specific response types. While accuracy measures address the likelihood of a correct response, the distance measure reflects that different response types range in their similarity to the target. Model fit was assessed. The frequency of significant improvements and the average magnitude of improvements for each summary statistic were compared between treatment groups and a control group. Effect sizes for each model-based statistic were compared with the effect size for the standard accuracy measure. RESULTS: Interrater and intrarater reliability were near perfect, on average, though compromised somewhat by phonological-level errors. The effects of treatment were more evident, in terms of both frequency and magnitude, when using the distance measure versus the other accuracy statistics. CONCLUSIONS: Consideration of item difficulty and response types revealed additional effects of treatment on naming scores beyond those observed for the standard accuracy measure. The results support theories that assume naming ability is decomposable into subabilities rather than being monolithic, suggesting new opportunities for measuring treatment outcomes. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.17019515.

Disentangling the Psycholinguistic Loci of Anomia with Cognitive Psychometric Models.

This article reviews advanced statistical techniques for measuring impairments in object naming, particularly in the context of stroke-induced aphasia. Traditional testing strategies can be challenged by the multifaceted nature of impairments that arise due to the complex relationships between localized brain damage and disruption to the cognitive processes required for successful object naming. Cognitive psychometric models can combine response-type analysis with item-response theory to yield accurate estimates of multiple abilities using data collected from a single task. The models also provide insights about how the test items can be challenging in different ways. Although more work is needed to fully optimize their clinical utility in practice, these formal concepts can guide thoughtful selection of stimuli used in treatment or assessment, as well as providing a framework to interpret response-type data.

A Cognitive Psychometric Investigation of Word Production and Phonological Error Rates in Logopenic Progressive Aphasia.

Purpose This study investigated the relationship between word production rates (WPRs) and phonological error rates (PERs) in generative and responsive tasks in logopenic progressive aphasia (lvPPA). We examined whether a portion of the reduced WPR during generative tasks related directly to phonological impairments affecting PER on all tasks, irrespective of other task differences that contributed to WPR. Method Two cognitive psychometric models were hypothesized and fit to the total number of words produced and the number of phonological errors produced by 22 participants on 10 tasks. Bayesian inference was used to construct posterior distributions of participant ability and task difficulty parameters. Model fit statistics were compared. Association strengths for average generative WPR and average responsive PER were also evaluated with linear least-squares regression. Results Average generative WPR and average responsive PER were significantly associated (r = -.77, p = .00002). A cognitive psychometric model that assumed reduced WPR on generative tasks reflects a portion of general phonological impairment yielded better fit than a model that ignored performance differences between generative and responsive tasks. Generative fluency tasks that elicited few phonological errors still reflected phonological impairment, via suppression. Individual participants were estimated to suppress between 62% and 93% of phonological errors on generative tasks that would have emerged on responsive tasks. Conclusions Suppression of phonological errors may present as decreased WPR on generative tasks in lvPPA. Failure to account for this suppression tendency may lead to overestimation of phonological ability. The findings indicate the need to account for task demands in assessing lvPPA.

Effect of Bilateral Opercular Syndrome on Speech Perception.

Speech perception ability and structural neuroimaging were investigated in two cases of bilateral opercular syndrome. Due to bilateral ablation of the motor control center for the lower face and surrounds, these rare cases provide an opportunity to evaluate the necessity of cortical motor representations for speech perception, a cornerstone of some neurocomputational theories of language processing. Speech perception, including audiovisual integration (i.e., the McGurk effect), was mostly unaffected in these cases, although verbal short-term memory impairment hindered performance on several tasks that are traditionally used to evaluate speech perception. The results suggest that the role of the cortical motor system in speech perception is context-dependent and supplementary, not inherent or necessary.

Connections and selections: Comparing multivariate predictions and parameter associations from latent variable models of picture naming.

Connectionist simulation models and processing tree mathematical models of picture naming have complementary advantages and disadvantages. These model types were compared in terms of their predictions of independent language measures and their associations between model components and measures that should be related according to their theoretical interpretations. The models were tasked with predicting independent picture naming data, neuropsychological test scores of semantic association and speech production, grammatical categories of formal errors, and lexical properties of target items. In all cases, the processing tree model parameters provided better predictions and stronger associations between parameters and independent language measures than the connectionist simulation model. Given the enhanced generalizability of latent variable measurements afforded by the processing tree model, evidence regarding mechanistic and representational features of the speech production system are re-evaluated. Several areas are indicated as being potentially viable targets for elaboration of the mechanistic descriptions of picture naming errors.

A cognitive psychometric model for assessment of picture naming abilities in aphasia.

Picture naming impairments are a typical feature of stroke-induced aphasia. Overall accuracy and rates of different error types are used to make inferences about the severity and nature of damage to the brain's language network. Currently available assessment tools for picture naming accuracy treat it as a unidimensional measure, while assessment tools for error types treat items homogenously, contrary to findings from psycholinguistic investigations of word production. We created and tested a new cognitive psychometric model for assessment of picture naming responses, using cognitive theory to specify latent processing decisions during the production of a naming attempt, and using item response theory to separate the effects of item difficulty and participant ability on these internal processing decisions. The model enables multidimensional assessment of latent picture naming abilities on a common scale, with a relatively large cohort for normative reference. We present the results of 4 experiments testing our interpretation of the model's parameters, as they apply to picture naming predictions, lexical properties of the items, statistical properties of the lexicon, and participants' scores on other tests. We also created a website for researchers and clinicians to analyze item-level data using our model, providing estimates of latent abilities and percentile scores, as well as credible intervals to help gauge the reliability of the estimated model parameters and identify meaningful changes. To the extent that the model is successful, the estimated parameter values may aid in treatment decisions and progress monitoring, or they may help elucidate the functional properties of brain networks. (PsycINFO Database Record

Evaluating quantitative and conceptual models of speech production: how does SLAM fare?

In a previous publication, we presented a new computational model called SLAM (Walker & Hickok, Psychonomic Bulletin & Review doi: 10.3758/s13423-015-0903 ), based on the hierarchical state feedback control (HSFC) theory (Hickok Nature Reviews Neuroscience, 13(2), 135-145, 2012). In his commentary, Goldrick (Psychonomic Bulletin & Review doi: 10.3758/s13423-015-0946-9 ) claims that SLAM does not represent a theoretical advancement, because it cannot be distinguished from an alternative lexical + postlexical (LPL) theory proposed by Goldrick and Rapp (Cognition, 102(2), 219-260, 2007). First, we point out that SLAM implements a portion of a conceptual model (HSFC) that encompasses LPL. Second, we show that SLAM accounts for a lexical bias present in sound-related errors that LPL does not explain. Third, we show that SLAM's explanatory advantage is not a result of approximating the architectural or computational assumptions of LPL, since an implemented version of LPL fails to provide the same fit improvements as SLAM. Finally, we show that incorporating a mechanism that violates some core theoretical assumptions of LPL-making it more like SLAM in terms of interactivity-allows the model to capture some of the same effects as SLAM. SLAM therefore provides new modeling constraints regarding interactions among processing levels, while also elaborating on the structure of the phonological level. We view this as evidence that an integration of psycholinguistic, neuroscience, and motor control approaches to speech production is feasible and may lead to substantial new insights.

Bridging computational approaches to speech production: The semantic-lexical-auditory-motor model (SLAM).

Speech production is studied from both psycholinguistic and motor-control perspectives, with little interaction between the approaches. We assessed the explanatory value of integrating psycholinguistic and motor-control concepts for theories of speech production. By augmenting a popular psycholinguistic model of lexical retrieval with a motor-control-inspired architecture, we created a new computational model to explain speech errors in the context of aphasia. Comparing the model fits to picture-naming data from 255 aphasic patients, we found that our new model improves fits for a theoretically predictable subtype of aphasia: conduction. We discovered that the improved fits for this group were a result of strong auditory-lexical feedback activation, combined with weaker auditory-motor feedforward activation, leading to increased competition from phonologically related neighbors during lexical selection. We discuss the implications of our findings with respect to other extant models of lexical retrieval.

Short-form Philadelphia naming test: rationale and empirical evaluation.

PURPOSE: To create two matched short forms of the Philadelphia Naming Test (PNT; Roach, Schwartz, Martin, Grewal, & Brecher, 1996) that yield similar results to the PNT for measuring anomia. METHOD: In Study 1, archived naming data from 94 individuals with aphasia were used to identify which PNT items should be included in the short forms. The 2 constructed sets of 30 items, PNT30-A and PNT30-B, were validated using archived data from a separate group of 56 individuals with aphasia. In Study 2, the reliability of the PNT, PNT30-A, and PNT30-B across independent test administrations was evaluated with a new group of 25 individuals with aphasia who were selected to represent the full range of naming impairment. RESULTS: In Study 1, PNT30-A and PNT30-B were found to be internally consistent, and accuracy scores on these subsets of items were highly correlated with the full PNT. In Study 2, PNT accuracy was extremely reliable over the span of 1 week, and independent administrations of PNT30-A and PNT30-B produced similar results to the PNT and to each other. CONCLUSION: The short forms of the PNT can be used to reliably estimate PNT performance, and the results can be compared to the provided norms. The 2 matched tests allow for the measurement of change in an individual's naming ability.

Neuroanatomical dissociation for taxonomic and thematic knowledge in the human brain.

It is thought that semantic memory represents taxonomic information differently from thematic information. This study investigated the neural basis for the taxonomic-thematic distinction in a unique way. We gathered picture-naming errors from 86 individuals with poststroke language impairment (aphasia). Error rates were determined separately for taxonomic errors ("pear" in response to apple) and thematic errors ("worm" in response to apple), and their shared variance was regressed out of each measure. With the segmented lesions normalized to a common template, we carried out voxel-based lesion-symptom mapping on each error type separately. We found that taxonomic errors localized to the left anterior temporal lobe and thematic errors localized to the left temporoparietal junction. This is an indication that the contribution of these regions to semantic memory cleaves along taxonomic-thematic lines. Our findings show that a distinction long recognized in the psychological sciences is grounded in the structure and function of the human brain.

Support for anterior temporal involvement in semantic error production in aphasia: new evidence from VLSM.

Semantic errors in aphasia (e.g., naming a horse as "dog") frequently arise from faulty mapping of concepts onto lexical items. A recent study by our group used voxel-based lesion-symptom mapping (VLSM) methods with 64 patients with chronic aphasia to identify voxels that carry an association with semantic errors. The strongest associations were found in the left anterior temporal lobe (L-ATL), in the mid- to anterior MTG region. The absence of findings in Wernicke's area was surprising, as were indications that ATL voxels made an essential contribution to the post-semantic stage of lexical access. In this follow-up study, we sought to validate these results by re-defining semantic errors in a manner that was less theory dependent and more consistent with prior lesion studies. As this change also increased the robustness of the dependent variable, it made it possible to perform additional statistical analyses that further refined the interpretation. The results strengthen the evidence for a causal relationship between ATL damage and lexically-based semantic errors in naming and lend confidence to the conclusion that chronic lesions in Wernicke's area are not causally implicated in semantic error production.

A large, searchable, web-based database of aphasic performance on picture naming and other tests of cognitive function.

Many research questions in aphasia can only be answered through access to substantial numbers of patients and to their responses on individual test items. Since such data are often unavailable to individual researchers and institutions, we have developed and made available the Moss Aphasia Psycholinguistics Project Database: a large, searchable, web-based database of patient performance on psycholinguistic and neuropsychological tests. The database contains data from over 240 patients covering a wide range of aphasia subtypes and severity, some of whom were tested multiple times. The core of the archive consists of a detailed record of individual-trial performance on the Philadelphia (picture) Naming Test. The database also contains basic demographic information about the patients and patients' overall performance on neuropsychological assessments as well as tests of speech perception, semantics, short-term memory, and sentence comprehension. The database is available at http://www.mappd.org/ .

Anterior temporal involvement in semantic word retrieval: voxel-based lesion-symptom mapping evidence from aphasia.

Analysis of error types provides useful information about the stages and processes involved in normal and aphasic word production. In picture naming, semantic errors (horse for goat) generally result from something having gone awry in lexical access such that the right concept was mapped to the wrong word. This study used the new lesion analysis technique known as voxel-based lesion-symptom mapping to investigate the locus of lesions that give rise to semantic naming errors. Semantic errors were obtained from 64 individuals with post-stroke aphasia, who also underwent high-resolution structural brain scans. Whole brain voxel-based lesion-symptom mapping was carried out to determine where lesion status predicted semantic error rate. The strongest associations were found in the left anterior to mid middle temporal gyrus. This area also showed strong and significant effects in further analyses that statistically controlled for deficits in pre-lexical, conceptualization processes that might have contributed to semantic error production. This study is the first to demonstrate a specific and necessary role for the left anterior temporal lobe in mapping concepts to words in production. We hypothesize that this role consists in the conveyance of fine-grained semantic distinctions to the lexical system. Our results line up with evidence from semantic dementia, the convergence zone framework and meta-analyses of neuroimaging studies on word production. At the same time, they cast doubt on the classical linkage of semantic error production to lesions in and around Wernicke's area.