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Time reference is used to build the temporal framework of discourse and is essential in ensuring efficient communication. Several studies have reported time reference deficits in fluent and non-fluent aphasia and have shown that tenses (past, present, future) are not all impaired to the same extent. However, there is little consensus on the dissociations between tenses, and the question of the influence of the type of aphasia (fluent vs. non-fluent) on time reference remains open. Therefore, a systematic review and an individual participant data meta-analysis (or mega-analysis) were conducted to determine (1) whether one tense is more impaired than another in fluent and non-fluent aphasia and, if so, (2) which task and speaker-related factors moderate tense effects. The systematic review resulted in 35 studies reporting the performance in time reference of 392 participants. The mega-analysis was then performed on 23 studies for a total of 232 participants and showed an alteration of past tense compared to present and future tenses in both types of aphasia. The analysis also showed a task and an age effect on time reference but no gender effect, independently of tenses. These results add to our knowledge of time reference in aphasia and have implications for future therapies. [ABSTRACT FROM AUTHOR]

Time reference is used to build the temporal framework of discourse and is essential in ensuring efficient communication. Several studies have reported time reference deficits in fluent and non-fluent aphasia and have shown that tenses (past, present, future) are not all impaired to the same extent. However, there is little consensus on the dissociations between tenses, and the question of the influence of the type of aphasia (fluent vs. non-fluent) on time reference remains open. Therefore, a systematic review and an individual participant data meta-analysis (or mega-analysis) were conducted to determine (1) whether one tense is more impaired than another in fluent and non-fluent aphasia and, if so, (2) which task and speaker-related factors moderate tense effects. The systematic review resulted in 35 studies reporting the performance in time reference of 392 participants. The mega-analysis was then performed on 23 studies for a total of 232 participants and showed an alteration of past tense compared to present and future tenses in both types of aphasia. The analysis also showed a task and an age effect on time reference but no gender effect, independently of tenses. These results add to our knowledge of time reference in aphasia and have implications for future therapies.

The present study aims at investigating verb inflection in aphasia and semantic dementia. In particular, it addresses the contribution of time reference and morphological complexity. Moreover, it investigates whether the lexical properties of the verb, such as argument structure and lexical aspect interact with the production of tense. Ten individuals with (different types of) stroke aphasia and five individuals with semantic dementia and their respective control groups conducted a sentence completion task. Three tenses were tested: past perfective, past imperfective and present. All tenses had to be produced with three different verb classes, which differed with respect to syntactic and semantic properties: unergative, unaccusative and transitive verbs. The findings imply problems with marking aspect and an interaction between inflection and lexical aspect but no effect of morphological complexity or across the board difficulties with reference to the past in aphasia. Moreover, the results suggest problems with inflection in semantic dementia, an interaction between inflection and lexical aspect and a selective difficulty with imperfective tenses. The study contributes to a better understanding of inflection problems in aphasia and it provides evidence for inflection problems in semantic dementia. [ABSTRACT FROM AUTHOR]

Writing has long been considered to be dependent on speaking. However, modality-specific dissociations between written and spoken word production imply that word production is supported by distinct neural mechanisms in writing, which can be impaired or spared regardless of the intactness of spoken word production. Rapp et al. (2015). Modality and morphology: What we write may not be what we say. Psychological Science, 26, 892-902 documented a double dissociation where problems with regular inflections were selectively restricted to writing or speaking. We report on two English-speaking aphasic individuals who exhibit this same modality-specific dissociation of inflectional processing, replicating the original findings. We expand on Rapp et al.’s study by examining whether the dissociations observed with regular inflections extend to other morphological forms, such as derivation and irregular inflection. Results showed that the dissociation holds for derivation; however, both participants were impaired with irregular inflections in both output modalities. Implications of these findings for morphological processing and the independence of the orthographic system are discussed. [ABSTRACT FROM AUTHOR]

This paper investigates the production of German plural nouns by two aphasic participants with non-fluent speech production. Experimental tasks included two production tasks: (1) picture naming of single and multiple objects, and (2) an elicitation task of singular and plural nouns. Materials were controlled for regularity and predictability of plural form, and for dominance of number, referring to the relative difference in word form frequency between a singular and its corresponding plural form. Both regularity and number dominance have been shown to affect plural noun production in both unimpaired and aphasic speakers, but the underlying functional origin of these effects is still a matter of debate. The results point to differences in the lexical representation and processing of regular and irregular German plural nouns. Thus, the data are in line with the dual mechanism account. [ABSTRACT FROM AUTHOR]

Within the domain of inflectional morpho-syntax, differential processing of regular and irregular forms has been found in healthy speakers and in aphasia. One view assumes that irregular forms are retrieved as full entities, while regular forms are compiled on-line. An alternative view holds that a single mechanism oversees regular and irregular forms. Arabic offers an opportunity to study this phenomenon, as Arabic nouns contain a consonantal root, delivering lexical meaning, and a vocalic pattern, delivering syntactic information, such as gender and number. The aim of this study is to investigate morpho-syntactic processing of regular (sound) and irregular (broken) Arabic plurals in patients with morpho-syntactic impairment. Three participants with acquired agrammatic aphasia produced plural forms in a picture-naming task. We measured overall response accuracy, then analysed lexical errors and morpho-syntactic errors, separately. Error analysis revealed different patterns of morpho-syntactic errors depending on the type of pluralization (sound vs broken). Omissions formed the vast majority of errors in sound plurals, while substitution was the only error mechanism that occurred in broken plurals. The dissociation was statistically significant for retrieval of morpho-syntactic information (vocalic pattern) but not for lexical meaning (consonantal root), suggesting that the participants' selective impairment was an effect of the morpho-syntax of plurals. These results suggest that irregular plurals forms are stored, while regular forms are derived. The current findings support the findings from other languages and provide a new analysis technique for data from languages with non-concatenative morpho-syntax. [ABSTRACT FROM AUTHOR]

Consensus recommendations for three variants of primary progressive aphasia (PPA), the non-fluent/agrammatic, logopenic and semantic variants, were published in 2011 [Gorno-Tempini et al., 2011]. These recommendations describe the most characteristic language impairments for each variant. However, studies using these criteria in larger groups of patients revealed serious limitations concerning their application. Some of these limitations are related to imprecisions in the description of language features, especially for grammatical features. The aim of this review was to examine studies of inflectional morphology in three variants of PPA and in the disease that is the most relevant for differential diagnosis, namely Alzheimer's disease. MedLine, CINAHL and PsycINFO electronic databases were searched to retrieve all relevant peer-reviewed articles published in English language journals. Despite the focus that has been placed on agrammatism by the consensus recommendations, the studies reviewed do not systematically report impairments of inflectional morphology in the non-fluent/agrammatic variant. Studies also show that some individuals with the logopenic variant present with substantial inflection impairments. Contrary to expectations, some studies reveal the presence of morphological difficulties in the semantic variant. These difficulties concern mostly the production of irregular, low-frequency verbs while regular verbs are spared. Similar difficulties are also reported in studies of people with Alzheimer's disease. Overall, the results show the need to more clearly define the criteria related to grammar and morphology and to better characterise impairment severity. Future research on primary progressive aphasia and other degenerative diseases with language impairments will help refine our expectations regarding language features that characterise each profile. [ABSTRACT FROM AUTHOR]

Abstract: Across most languages, verbs produced by agrammatic aphasic individuals are frequently marked by syntactically and semantically inappropriate inflectional affixes, such as Last night, I walking home. As per language production models, verb inflection errors in English agrammatism could arise from three potential sources: encoding the verbs’ morphology based on temporal information at the conceptual level, accessing syntactic well-formedness constraints of verbal morphology, and encoding morphophonological form. We investigate these aspects of encoding verb inflections in agrammatic aphasia. Using three sentence completion experiments, it was demonstrated that production of verb inflections was impaired whenever temporal reference was involved; while morphological complexity and syntactic constraints were less likely to be the source of verb inflection errors in agrammatism. These findings are discussed in relation to current language production models. [Copyright &y& Elsevier]

Verb inflection errors, often seen in agrammatic aphasic speech, have been attributed to either impaired encoding of diacritical features that specify tense and aspect, or to impaired affixation during phonological encoding. In this study we examined the effect of semantic markedness, word form frequency and affix frequency, as well as accuracy and error patterns, in an attempt to evaluate whether diacritical or affixation operations are impaired. Verb inflections (V+ing, V+ed, V+s, and V stem in present progressive, past, present 3rd person singular, and future tense contexts, respectively) were elicited in eight mild-moderate agrammatic aphasic individuals in a sentence context using a picture description task. Results revealed that the majority of verbs produced were affixed (75%) although accuracy was low (36%). Word form frequency was found to be a significant predictor of the accuracy with which verb inflections were produced; while affix frequency and semantic markedness were not found to influence accuracy. These results suggest that a diacritical deficit is more likely to undermine the production of verb inflections than a affixation deficit, and indicate that when diacritical processes are compromised, word form frequency is likely to influence production of verb inflections in agrammatic aphasia. [Copyright &y& Elsevier]

Syntactic trees, or phrase markers, have originally been suggested as a representation of syntax in the mind based on purely linguistic grounds. In this paper, the psychological reality of syntactic trees and hierarchical ordering is explored from another perspective—that of the neuropsychology of language breakdown. The study reported here examined several syntactic domains that rely on different nodes in the tree—tense and agreement verb inflection, subordinations, interrogatives, and verb movement, through a study of 14 Hebrew- and Palestinian Arabic-speaking agrammatic aphasics and perusal of the cross-linguistic literature. The results show that the impairment in agrammatic production is highly selective and lends itself to characterization in terms of a deficit in the syntactic tree. The complex pattern of dissociations follows from one underlying deficit—the inaccessibility of high nodes of the syntactic tree to agrammatic speakers. Structures that relate to high nodes of the tree are impaired, while “lower” structures are spared. [ABSTRACT FROM AUTHOR]