Naming as a window to word retrieval changes in healthy and pathological ageing: Methodological considerations.

BACKGROUND: Word retrieval skills change across the lifespan. Permanent alterations in the form of decreased accuracy or increased response time can be a consequence of both normal ageing processes or the presence of acquired and neurodegenerative disorders (e.g., aphasia and dementia). Despite the extensive literature exploring the neuroanatomical underpinnings of word retrieval, psycholinguistic, biolinguistic and theoretical explanations, and the vast amount of evidence from primary and secondary language disorders, the best approach to consistently capture these changes is yet to be discovered. AIMS: The goal of this paper is to determine which method(s) stand(s) as the most suitable candidate(s) to provide an accurate picture of word retrieval in the oral production of different groups of adult speakers, including cases of healthy ageing, preclinical Alzheimer's disease (AD), mild cognitive impairment (MCI), aphasia and dementia. METHODS & PROCEDURES: Using an integrative review of recent peer-reviewed journal articles, we provide an overview of the different behavioural methods traditionally used to measure oral naming skills in research-oriented and clinical protocols and discuss their main advantages and limitations. MAIN CONTRIBUTION: Most existing studies are based on the results of people with diagnosed language disorders. Despite the growing interest, the reliability of the majority of the tasks to detect subtle changes associated with healthy ageing, MCI and preclinical AD are yet to be demonstrated, and the delicate balance between informativeness and efficiency (especially in terms of administration time and variable control) in experimental protocols is yet to be achieved. In this article we propose the pursuit of an integrative overarching methodology to characterize all naming deficits (from anecdotal to permanent) and all adult populations (from healthy to pathological ageing). CONCLUSIONS & IMPLICATIONS: A combination of spontaneous speech data and results from structured tasks stands as the best approach to capture changes in word retrieval skills of adult speakers with and without observable deficits. This review can guide future reflections on the necessary prerequisites of purpose-oriented, sensitive and reliable protocols for the detection of incipient word retrieval problems, thus contributing to the early diagnosis and the design of personalized multicomponent treatments. WHAT THIS PAPER ADDS: What is already known on this subject Word retrieval skills change during adulthood as a consequence of the neurological degradation associated with ageing. These changes are more dramatic in the event of acquired and neurodegenerative disorders. Numerous studies based on people with observable language disorders have addressed the multiplicity of factors involved in word retrieval and provided evidence of potential loci of impairment from a neuroanatomical, cognitive and/or (psycho-)linguistic perspective. What this paper adds to existing knowledge This study focuses on methodological strategies to assess naming skills and provides a reflection on generally accepted good practices and unresolved challenges to inform task selection, emphasizing the necessity for a combination of methods to best capture the actual problems and needs of people confronting word retrieval difficulties in their daily lives. Task selection, variable control and administration time stand as key concepts to adjust to the requirements of research and clinical contexts. What are the potential or actual clinical implications of this work? The results of this review can orient future research towards the creation of sensitive, reliable and (ecologically) valid materials for the (early) detection of word retrieval deficits and for the customization of treatment protocols to alleviate or palliate their effects.

Prepositions and pronouns in connected discourse of individuals with aphasia.

The lexical-grammatical divide has been a widely addressed topic in aphasia. Speech parts are generally classified as either belonging to a lexical or a grammatical category based on the frequency of acquisition of new members in their paradigms (open vs. closed classes), thus neglecting heterogeneity within categories. Such an approach has led to contradictory findings. First, prepositions form closed classes, but are classically taken as lexical items. Pronouns, also belonging to a closed class, are analyzed as grammatical elements. Second, both within the group of prepositions and pronouns, forms with different syntactic and semantic properties co-exist. Following the theoretical notions granted by a usage-based theory of grammar, the ProGram theory, and taking focalizability as the classification criteria, we hypothesize that individuals with non-fluent aphasias will experience more severe problems with grammatical prepositions and pronouns, given that these elements are secondary and dependent, whereas informants in the fluent group will experience more severe trouble with lexical forms, potentially primary and independent. We focused on the performance of nine Spanish-speaking individuals with aphasia from the Rosell (2005) corpus. Samples of 300 words were transcribed and analyzed. As predicted, grammatical prepositions were found to be more severely compromised in the speech output of individuals with deficits of motor predominance, whereas lexical prepositions are more severely affected in individuals with deficits of sensory predominance. Although less conclusively, the same tendency holds in the case of pronouns. Our results, consistent with previous findings, confirm the heterogeneity of prepositions and pronouns, which should no longer be analyzed en bloc.

Imageability ratings across languages.

Imageability is a psycholinguistic variable that indicates how well a word gives rise to a mental image or sensory experience. Imageability ratings are used extensively in psycholinguistic, neuropsychological, and aphasiological studies. However, little formal knowledge exists about whether and how these ratings are associated between and within languages. Fifteen imageability databases were cross-correlated using nonparametric statistics. Some of these corresponded to unpublished data collected within a European research network-the Collaboration of Aphasia Trialists (COST IS1208). All but four of the correlations were significant. The average strength of the correlations (rho = .68) and the variance explained (R 2 = 46%) were moderate. This implies that factors other than imageability may explain 54% of the results. Imageability ratings often correlate across languages. Different possibly interacting factors may explain the moderate strength and variance explained in the correlations: (1) linguistic and cultural factors; (2) intrinsic differences between the databases; (3) range effects; (4) small numbers of words in each database, equivalent words, and participants; and (5) mean age of the participants. The results suggest that imageability ratings may be used cross-linguistically. However, further understanding of the factors explaining the variance in the correlations will be needed before research and practical recommendations can be made.

Overcoming discourse-linking difficulties in aphasia: The case of clitic pronouns.

The present study aims to contribute to the ongoing discussion about the impact of discourse-linking deficits on the performance of individuals with aphasia by providing new data from a set of rarely investigated constructions: sentences in which a clitic pronoun coexists alongside with the full DP it agrees with. To do so, we use data of individuals with non-fluent aphasias who need to overcome the difficulties in direct object (accusative) clitic production. This results in overproduction of non-target clitic right dislocations (RDs) and clitic doubling (CD). Data from 15 individual's native speakers of Spanish and Catalan are discussed. Data complement the results of previous investigations on discourse-linking effects in these languages, allowing the interpretation of results across constructions.

Cross-linguistic adaptations of The Comprehensive Aphasia Test: Challenges and solutions.

Comparative research on aphasia and aphasia rehabilitation is challenged by the lack of comparable assessment tools across different languages. In English, a large array of tools is available, while in most other languages, the selection is more limited. Importantly, assessment tools are often simple translations and do not take into consideration specific linguistic and psycholinguistic parameters of the target languages. As a first step in meeting the needs for comparable assessment tools, the Comprehensive Aphasia Test is currently being adapted into a number of languages spoken in Europe. In this article, some key challenges encountered in the adaptation process and the solutions to ensure that the resulting assessment tools are linguistically and culturally equivalent, are proposed. Specifically, we focus on challenges and solutions related to the use of imageability, frequency, word length, spelling-to-sound regularity and sentence length and complexity as underlying properties in the selection of the testing material.

Print-Tuning Lateralization and Handedness: an Event-Related Potential Study in Dyslexic Higher Education Students.

Despite their ample reading experience, higher education students with dyslexia still show deficits in reading and reading-related skills. Lateralized print tuning, the early sensitivity to print of the left parietal cortex signalled by the N1 event-related potential (ERP) component, differs between beginning dyslexic readers and controls. For adults, the findings are mixed. The present study aims to investigate whether print tuning, as indexed by the N1 component, differs between 24 students with dyslexia and 15 non-dyslexic controls. Because handedness has been linked to lateralization, first, a separate analysis was conducted including only right-handed participants (n = 12 in both groups), like in most previous studies. ERPs were measured during a judgement task, requiring visual, phonological, or semantic judgments. In both groups, the N1 was earlier and stronger in the left than in the right hemisphere. However, when only strongly right-handed participants were evaluated, the N1 was less left-lateralized for participants with dyslexia as compared with controls. Participants with dyslexia had longer reaction times during the ERP experiment and performed worse on many reading (-related) tasks. These findings suggest that abnormal print tuning can still be found among higher education students with dyslexia and that handedness should be regarded in the study of print tuning.

Tense and agreement impairment in Ibero-Romance.

We examine the inflectional productions of seven Catalan, seven Galician, and seven Spanish speaking agrammatic subjects in an elicitation and a sentence repetition task and consider them in the light of the Tree Pruning Hypothesis (TPH). The results show relatively spared subject person/number agreement with the verb and impaired tense marking for all subjects in all the languages. Recent reformulations of syntactic theory [Chomsky (1999) MIT Occasional Papers in Linguistics (vol. 18). MA: The MIT Press; (2000). Step by Step: Essays on Minimalist Syntax in Honor of Howard Lasnik (pp. 89-155). Cambridge, MA: The MIT Press] regarding the locus of agreement force a reconsideration of the TPH for it to make the desired predictions; we adopt Cinque's [(1999) Adverbs and Functional Heads: A Cross-linguistic Perspective. Oxford: Oxford University Press] array of functional mood/tense/aspect projections and we show that subject agreement must occur between the subject DP and a low functional head for selective impairment to result. Feature underspecification, formerly considered, is rendered unnecessary.