Francine Kohen

Assessment of the ability to process semantic and phonological aspects of words in aphasia: A multi‐measurement approach

Background: Aphasia can disrupt processing of semantic and/or phonological aspects of words and each of these domains involves multiple operations. Adequate assessment of word processing requires multiple measurements probing in each domain. This research was supported by grants from the National Institutes of Health to Moss Rehabilitation Research Institute (DC 00191‐21, PI: Myrna Schwartz) and to Temple University (DC01924‐11, PI: Nadine Martin). We thank Paula Sobel, Adelyn Brecher, Joe Marin, Jennifer Ayala, Kelly Bowes, Stephanie Tempest, and Lianne DiMarco for their help in collecting and organising the data reported here. We are especially grateful to the people who participated in these studies, and we thank them for their interest and support. Aims: This paper aims to facilitate accurate and comprehensive testing of the multiple operations involved in semantic and phonological processing of spoken words. Methods & Procedures: Normative data (means and standard deviations) from aphasic samples on six measures of input semantic processing and five measures of input phonological processing are provided. Additionally, scores on these measures are correlated with performance on a picture‐naming test to determine whether they could predict performance in word production. The benefits of using a multi‐measurement approach are discussed. Outcome & Results: We demonstrate how these norms can be used to establish z‐score profiles of an individuals semantic and phonological abilities with reference to the aphasic sample. Additionally, we provide evidence that the measures of input processing on the semantic and phonological batteries can predict response patterns in a production task, picture naming. Z‐scores on the measures were positively correlated with picture‐naming accuracy, and measures in each domain followed a predicted pattern of correlation with error patterns in naming. Conclusions: Using the means and standard deviations from this study, a clinician or researcher can establish z‐score profiles of participants that will indicate the severity of semantic or phonological impairment compared with other individuals with aphasia. Comparison with this reference group will aid in the development of a therapy programme that is at an appropriate level of difficulty and will facilitate interpretation of progress being made in treatment. Additionally, this battery of input measures can be used to estimate patterns of output (correct and erroneous responses) in picture naming.

Computerised training for impairments of word comprehension and retrieval in aphasia

Background: Semantic comprehension training paired with verbal production leads to improved word retrieval in individuals with aphasia. Few studies have also examined effects of such training for word comprehension. MossTalk Words includes a training module to provide semantic comprehension training via computerised exercises. Variations in the treatment schedule may influence the impact of word retrieval and comprehension treatment gains. We extend our appreciation to our five participants and to Ruth Fink of the Albert Einstein Healthcare Network, who generously provided a copy of MossTalk Words for this study. This project was supported by NIH (NIDCD) grant P50 DC03888‐01A1 to the University of Florida (subcontract to Old Dominion University), and by the Dept. of Veterans Affairs Rehabilitation Research & Development Center of Excellence Grant F2182C to the Brain Rehabilitation Research Center, Gainesville, Florida. Aims: The purpose of this study was to investigate the effects of the Multi‐Mode Matching Exercises module of MossTalk Words for improving word comprehension and retrieval in individuals with aphasia. Effects of training were contrasted for two treatment schedules. Methods & Procedures: Five individuals with word retrieval impairments associated with aphasia participated. Two had word comprehension difficulties suggesting semantic anomia, and three others with intact comprehension had impairments suggesting phonologic anomia. In a single‐participant design, we investigated effects of training provided via computer with MossTalk multi‐mode matching exercises (spoken and written word/picture matching) paired with spoken rehearsal. All participated in two phases of training administered 1–2 times/week and 3–4 times/week, with order of phases counterbalanced across participants. Outcomes & Results: Improvements in word/picture yes/no verification for trained and some untrained words associated with large effect sizes (d>2.5) were evident in one of two participants when trained 1–2 times/week. Increases in picture naming associated with large effect sizes for trained words were noted in 5/5 participants when trained 4–5 times/week, and in 2/5 participants when trained 1–2 times/week. Increases in picture naming for untrained words were evident in 2/5 participants in the more frequent training schedule. At 1 month post training, picture naming performance remained above baseline levels, with little difference evident between sets trained with the two different training schedules. Conclusions: Computerised lexical training exercises may lead to increases in word comprehension and production, particularly for the target words trained. More frequent training leads to greater improvements during acquisition than less frequent training, but that advantage diminishes at 1 month post treatment, suggesting that a less frequent training schedule may be just as useful as more frequent training for promoting long‐term effects of lexical training.

Remediation of language processing in aphasia: Improving activation and maintenance of linguistic representations in (verbal) short-term memory

Background: Verbal short-term memory (STM) impairments are invariably present in aphasia. Word processing involves a minimal form of verbal STM, i.e., the time course over which semantic and phonological representations are activated and maintained until they are comprehended, produced, or repeated. Thus it is reasonable that impairments of word processing and verbal STM may co-occur. The co-occurrence of language and STM impairments in aphasia has motivated an active area of research that has revealed much about the relationship of these two systems and the effect of their impairment on language function and verbal learning (Freedman & Martin, 2001; Martin & Saffran, 1999; Trojano & Grossi, 1995). In keeping with this view a number of researchers have developed treatment protocols to improve verbal STM in order to improve language function (e.g., Koenig-Bruhin & Studer-Eichenberger, 2007). This account of aphasia predicts that treatment of a fundamental ability, such as STM, which supports language function, should lead to improvements that generalise to content and tasks beyond those implemented in treatment. Aims: We investigated the efficacy of a treatment for language impairment that targets two language support processes: verbal short-term memory (STM) and executive processing, in the context of a language task (repetition). We hypothesised that treatment of these abilities would improve repetition abilities and performance on other language tasks that require STM. Method: A single-participant, multiple-baseline, multiple-probe design across behaviours was used with a participant with conduction aphasia. The treatment involved repetition of words and nonwords under three “interval” conditions, which varied the time between hearing and repeating the stimulus. Measures of treatment effects included acquisition, maintenance, and follow-up data, effect sizes, and pre- and post-treatment performance on a test battery that varies the STM and executive function demands of language tasks. Outcomes & Results: Improvement of repetition was mostly specific to treated stimuli. Post-treatment measures of language ability indicated improvements in single and multiple word processing tasks, verbal working memory tasks, and verbal span. Conclusions: Treatment of STM and executive processes in the context of a word repetition task resulted in improvements in other non-treated language tasks. The approach used in this study can be incorporated into other language-processing tasks typically used in treatment of language disorders (e.g., sentence processing).

Effects of working memory load on processing of sounds and meanings of words in aphasia

Background: Language performance in aphasia can vary depending on several variables such as stimulus characteristics and task demands. This study focuses on the degree of verbal working memory (WM) load inherent in the language task and how this variable affects language performance by individuals with aphasia. Aims: The first aim was to identify the effects of increased verbal WM load on the performance of judgements of semantic similarity (synonymy) and phonological similarity (rhyming). The second aim was to determine if any of the following abilities could modulate the verbal WM load effect: semantic or phonological access, semantic or phonological short-term memory (STM), and any of the following executive processing abilities: inhibition, verbal WM updating, and set shifting. Method & Procedures: A total of 31 individuals with aphasia and 11 controls participated in this study. They were administered a synonymy judgement task and a rhyming judgement task under high and low verbal WM load conditions that were compared to each other. In a second set of analyses multiple regression was used to identify which factors (as noted above) modulated the verbal WM load effect. Outcomes & Results: For participants with aphasia, increased verbal WM load significantly reduced accuracy of performance on synonymy and rhyming judgements. Better performance in the low verbal WM load conditions was evident even after correcting for chance. The synonymy task included concrete and abstract word triplets. When these were examined separately the verbal WM load effect was significant for the abstract words, but not the concrete words. The same pattern was observed in the performance of the control participants. Additionally, the second set of analyses revealed that semantic STM and one executive function, inhibition ability, emerged as the strongest predictors of the verbal WM load effect in these judgement tasks for individuals with aphasia. Conclusions: The results of this study have important implications for diagnosis and treatment of aphasia. As the roles of verbal STM capacity, executive functions and verbal WM load in language processing are better understood, measurements of these variables can be incorporated into our diagnostic protocols. Moreover, if cognitive abilities such as STM and executive functions support language processing and their impairment adversely affects language function, treating them directly in the context of language tasks should translate into improved language function.

Word-Retrieval Treatment in Aphasia: Effects of Sentence Context

Word-retrieval treatment studies in aphasia have reported the greatest influences on picture naming for trained words. To increase treatment effects to untrained words and sentence contexts, we investigated a sentence-reading treatment hierarchy that moves from errorless to generative production of sentences incorporating target nouns and verbs. In an individual with nonfluent aphasia, treatment resulted in improved picture naming for nouns and verbs and generalized increases in numbers of grammatical sentences and content words following noun therapy. A second individual with fluent aphasia improved little in picture-naming and sentence-generation tasks for both nouns and verbs. This sentence-based word-retrieval training, in which semantic and syntactic processes are engaged, led to improvements in word-retrieval measures during spontaneous sentence generation, but only for the participant with nonfluent aphasia. Contrary to expectations, these changes were greater following noun therapy than they were following verb therapy.

Effects of syntactic and semantic argument structure on sentence repetition in agrammatism: Things we can learn from particles and prepositions

Background: Sentence production impairment in aphasia has been attributed to several possible sources that are not mutually exclusive. Linguistic accounts often attribute the difficulty to the complexity of a verbs syntactic and/or semantic argument structure. Cognitive processing accounts emphasise the reduced processing capacity observed in agrammatic aphasia, which in turn has been attributed to reduced semantic short-term memory (STM) or slowed processing. Aims: In this study we used verb particles and prepositions to investigate effects of differences in syntactic and semantic argument structure on sentence repetition in aphasia. We predicted that verb particles and sentences containing verb-particle constructions would be easier to repeat than prepositions and prepositional transitive sentences, as the former have a less-complex semantic and syntactic argument structure than the latter. Also, semantic and phonological spans were assessed to determine if a reduction in either capacity correlates with repetition ability. Methods & Procedures: Participants were eight individuals with chronic aphasia. The experimental task was repetition of transitive sentences balanced for length and lexical content containing either verb particles or prepositional object structures. Accuracy of sentence repetition and repetition of verb particles and prepositions within sentences was examined. We calculated the effect of structural complexity on the sentence repetition task as the difference between proportion correct of verb-particle constructions and prepositional transitives. Semantic and phonological STM spans and word spans were also assessed and correlated with this measure of the structural complexity effect on sentence repetition. Outcomes & Results: Verb-particle sentences were repeated correctly significantly more often than prepositional transitive sentences, and within those sentences verbal particles were repeated correctly significantly more often than prepositions. The effect was strongly associated with fluency scores: it was present in participants with low fluency scores, but not in those with high fluency scores. The phonological, but not the semantic, STM probe span measure correlated with both the difference in accurate repetition of verb-particle and prepositional transitive sentences and the particles and prepositions within those sentences. Conclusions: Results indicate that differences in argument structure of particle and preposition constructions influence sentence repetition in agrammatic aphasia. The finding that lower fluency scores are associated with poorer performance on more complex structures suggests that this effect is associated with agrammatism. The impact of these structural distinctions between particles and prepositions should be taken into account during development of treatment stimuli for those with agrammatism.

Assessment of linguistic and verbal short-term memory components of language abilities in aphasia

Some current models of aphasia emphasize a role of short-term memory in the processing of language and propose that the language impairment in aphasia involves impairment to cognitive processes that activate and maintain representations of words over the time-period needed to support single word and multiple word tasks, including verbal span tasks. This paper reports normative data from 39 people with aphasia and 16 age-matched neurotypical controls on a test battery for aphasia that assesses effects of increased short-term/working memory load on word and sentence processing as well as effects of linguistic variations on verbal short-term memory abilities Two concepts are discussed that capture the unique potential of this test battery for research and clinical practice: specificity of diagnosis and sensitivity to all degrees of aphasia severity, including mild aphasia. An analysis is included that shows how the performance of individuals with mild aphasia who achieve normal level of performance on the Western Aphasia Battery (Kertesz, 2006) show a decline in a temporal delay condition that is greater than performance of control participants. We also report preliminary data showing differential effects of adding a time interval before a response or between items to be compared: reduced accuracy for some individuals with aphasia and improved accuracy for others. The theoretical and clinical importance of this finding is discussed, as well as the overall potential for this test battery to be used in research and as a clinical tool. Finally, we discuss the relevance of this test battery to investigate functional communication abilities in aphasia.

Effects of semantic context on access to words of low imageability in deep-phonological dysphasia: a treatment case study

ABSTRACT Background: Deep dysphasia is a relatively rare subcategory of aphasia, characterised by word repetition impairment and a profound auditory-verbal short-term memory (STM) limitation. Repetition of words is better than nonwords (lexicality effect) and better for high-image than low-image words (imageability effect). Another related language impairment profile is phonological dysphasia, which includes all of the characteristics of deep dysphasia except for the occurrence of semantic errors in single word repetition. The overlap in symptoms of deep and phonological dysphasia has led to the hypothesis that they share the same root cause, impaired maintenance of activated representation of words, but that they differ in severity of that impairment, with deep dysphasia being more severe. Aims: We report a single-subject multiple baseline, multiple probe treatment study of a person who presented with a pattern of repetition that was consistent with the continuum of deep-phonological dysphasia: imageability and lexicality effects in repetition of single and multiple words and semantic errors in repetition of multiple-word utterances. The aim of this treatment study was to improve access to and repetition of low-imageability words by embedding them in modifier-noun phrases that enhanced their imageability. Methods & Procedures: The treatment involved repetition of abstract noun pairs. We created modifier-abstract noun phrases that increased the semantic and syntactic cohesiveness of the words in the pair. For example, the phrases “long distance” and “social exclusion” were developed to improve repetition of the abstract pair “distance-exclusion”. The goal of this manipulation was to increase the probability of accessing lexical and semantic representations of abstract words in repetition by enriching their semantic -syntactic context. We predicted that this increase in accessibility would be maintained when the words were repeated as pairs, but without the contextual phrase. Outcomes & Results: Treatment outcomes indicated that increasing the semantic and syntactic cohesiveness of low-imageability and low-frequency words later improved this participant’s ability to repeat those words when presented in isolation. Conclusions: This treatment approach to improving access to abstract word pairs for repetition was successful for our participant with phonological dysphasia. The approach exemplifies the potential value in manipulating linguistic characteristics of stimuli in ways that improve access between phonological and lexical-semantic levels of representation. Additionally, this study demonstrates how principles of a cognitive model of word processing can be used to guide treatment of word processing impairments in aphasia.