The Impact of Semantics and Syntax on Lexical Retrieval in Individuals With Aphasia

Nearly all people with aphasia (PWA) report difficulty with lexical retrieval (i.e., anomia). While there are several tasks used to measure lexical retrieval, each poses different degrees and types of challenges. For example, some studies have found that PWA performance varies depending on the type of lexical retrieval task. The tasks that have been used include lexical retrieval in isolation tasks (such as picture-naming), lexical retrieval in sentence level tasks (such as narration tasks), and lexical retrieval in sentence-completion tasks. Some studies have found no differences between the accuracy of lexical retrieval in isolation and at the sentence level (e.g., Basso, Razzano, Faglioni, and Zanobio, 1990), while others note evidence that lexical retrieval at the sentence level is more efficient than lexical retrieval in isolation (e.g., Pashek and Tompkins, 2002). Even within a study, there is inconsistency as to which task is more difficult. Pashek & Tompkins (2002) used the same stimuli across multiple tasks and found that not all PWA were more accurate on the picture naming task, consistent with differences noted in an earlier study by Williams and Canter (1982). When comparing lexical retrieval in isolation versus at the sentence level, the task demands naturally differ, thus providing different semantic and syntactic contexts for the target. The current study investigated the role of linguistic information on single word retrieval by manipulating syntactic and semantic information; that is, whether visual, semantic and syntactic contexts offer different levels of support for word retrieval in healthy controls and people with aphasia. We examined two different types of visual stimuli (images with associated verbs and isolated images), task demands, and the role of a related verb in sentence completion tasks in the two groups of individuals. Participant performance was evaluated for both accuracy and response time for a more detailed analysis. Our findings show differential performance between people with aphasia and healthy controls across experimental tasks: specifically, healthy controls tended to have more uniform performance for both accuracy and response time, while individuals with aphasia showed variability. Semantic content in visual images was both facilitative and inhibitory depending on the population and order of presentation, while auditory semantic content appears to be facilitatory in healthy controls. Previous research on sentence level lexical retrieval is supported for healthy controls, and inconclusive for individuals with aphasia. This study provides valuable information about the role of semantic and syntactic information in lexical retrieval. Healthy individuals are aided in lexical retrieval with both a syntactic frame and semantically related verbs, while individuals with aphasia show a great deal of variability. The findings further highlight the need for future research regarding individual factors that may impact conflict resolution in lexical retrieval in acquired brain injury populations

Communication Sampling Procedures

Learning Objectives (Ch. 5). After reading this chapter, students will be able to: Give a rationale for collecting communication samples List appropriate sampling contexts for age groups throughout the life span Describe manual and computer-assisted methods of analyzing communication samples List the aspects of language that should be assessed through communication sampling at each developmental level Discuss interpretation of language sampling and how it relates to treatment planning Name the aspects of speech that can be examined through communication sampling Describe how speech sampling supplements other assessments in this areas Explain the role that speech sampling plays in the assessment and treatment of speech disorder

Ageing as a Confound in Language Attrition Research: Lexical Retrieval, Language Use, and Cognitive and Neural Changes

Adult-onset native-language attrition most often occurs following a move to an environment where a non-native language is spoken. To date, the focus of attrition research has been in identifying what aspects of language are lost and which factors are crucial for the retention or attrition of the native language. Attrition is a gradual and fairly subtle process with no clear beginning or end. To best assess the effects of attrition, researchers tend to choose study participants who have lived in a non-native environment for a decade or longer (e.g., de Bot & Clyne, 1994; Schmid, 2002). The assumption is that the longer they have been removed from the native-language environment, the greater the degree of language attrition that should be observable. However, this principle regarding length of time and its relationship to language use overlaps with another, largely ignored, phenomenon: language changes associated with ageing. Are language changes due to long-term disuse conflated with age-related language changes in older adults who experience language attrition? This chapter explores changes to the adult lexicon as a result of attrition and ageing since the lexicon is considered a vulnerable part of the language system in both attrition and ageing. We consider neurophysiological changes that may play a role in language attrition and in non-pathological ageing to speculate whether the neurobiological sources of these two processes are similar or different. If attrition and ageing exert independent effects on lexical retrieval decline, we must consider the effects of each of these factors for word retrieval for older adult bilinguals immersed in a non-native-language environment

Primary Progressive Aphasias in Bilinguals and Multilinguals

Primary progressive aphasia (PPA) is the result of neurodegeneration affecting language abilities that continue to decline as the disease progresses. There are three main variants of PPA: non‐fluent, semantic, and logopenic. Deficits may occur in different areas of language, such as lexical retrieval, auditory comprehension, syntactic structure, processing morphological components, and repetition abilities. However, the impact on language is not comparable across all individuals with PPA; rather it differs for each of the different variants based on the underlying pattern of neural change. In bilinguals or multilinguals with PPA, the language decline has an added layer of complexity. Decline may occur across the different languages in parallel, or differentially, and a number of factors may affect the pattern of decline. Recognizing the factors that most affect language decline in bilinguals and multilinguals with PPA, along with identifying the neural changes occurring in the brain, can increase our understanding of language organization in the bilingual or multilingual brain. It should be noted that language decline is not the only decline associated with PPA, as changes in cognition and behaviour have also been observed, particularly in the later stages (e.g. Rosen et al. 2006). However, language is the most salient decline in PPA so we focus on language in this chapter