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The present electrophysiological study investigated irregular versus regular verb form processing in Swedish during reading. In line with previous results from other languages, overregularized verbs, i.e. incorrect irregular stem + regular past tense suffix combinations (e.g. * stjäl + de 'steal + past tense'), elicited a left-lateralized negativity (LAN) relative to correct irregulars (stal 'stole'), suggesting rule-based decomposition of regularly inflected words. Lack of a similar effect for misapplication of the irregular stem formation pattern on regular verbs (e.g. * löft 'lifted' instead of lyfte) suggests the involvement of different processing mechanisms, possibly whole word access, for irregular items, at least to some degree. A P600 showing reprocessing was seen for all incorrect forms. The results add cross-linguistic support for morphological decomposition in the verbal inflection of a language where results from previous neurolinguistic studies of nominal inflection have only suggested the use of full-form access to words. • ERPs of both overregularized and irregularized verbs in Swedish were recorded. • LAN obtained for overregularized verbs suggests rule-based decomposition. • Irregularized verbs elicited only a P600 relative to the correct variant. [ABSTRACT FROM AUTHOR]

Previous studies on the neuro-cognition of language have provided a strong case for systematic inter-individual variability in event-related potentials (ERPs) evoked during language processing. In the present study, we aimed at extending this evidence to the processing of morphologically complex words. We focused on German plural forms and tested two types of morphological violations: overapplications of regular plural morphemes ('regularizations') and of irregular plural morphemes ('irregularizations'). The group-level results showed a biphasic LAN-P600 response for regularizations, and a P600 for irregularizations. In line with previous reports, our analyses of inter-individual variability suggested that biphasic responses consisting of a negativity followed by a positivity are unlikely to exist at the individual level. Importantly, when analyzing the scalp distribution of ERPs elicited in participants supposed to show negativity-dominant responses, we found this to vary as a function of the type of morphological form: regularizations elicited a left-hemisphere response (LAN), while irregularizations a more widespread negativity (N400). Our results are consistent with dual-route accounts of morphological processing that distinguish between rule-based processing for regular inflection and memory retrieval for irregular inflection. At a more general level, our study shows that complementing group-level results with analyses of inter-individual variability can crucially contribute to a more detailed understanding of brain signatures of language. • Overapplications of regular plural forms elicited a LAN-P600 response at group-level. • Overapplications of irregular plural forms elicited a P600 response at group-level. • Some individuals showed a negativity-dominant, others a positivity-dominant response. • Negativity-dominant individuals showed a lateralized negativity with regularizations. • Analyses of inter-individual variability help to better understand ERP components. [ABSTRACT FROM AUTHOR]

How is morphological and morphosyntactic information processed during sentence reading? Are the neural mechanisms underlying word- and phrase-level combinatorial processing overlapping or distinct? Here, electroencephalography (EEG) and magnetoencephalography (MEG) responses were recorded simultaneously during silent reading of Finnish sentences. The experimental conditions included 1) well-formed grammatical sentences (correct condition), 2) sentences containing morphosyntactic violations (adjective–noun number agreement violations), 3) morphological violations (incorrect stem allomorph and inflectional suffix combination), and 4) combined violations, containing both morphosyntactic and morphological violations. Signal space and source modeling results showed that morphosyntactic violations elicited a left anterior negativity effect, generated particularly in the left inferior frontal area. Morphological violations elicited a widespread negativity, resembling the N400. The neural sources of this negativity were localized most prominently to the right temporal cortical networks. Furthermore, all violations elicited P600 effects with similar widespread bilateral fronto-temporal neural generators that did not differ between morphosyntactic and morphological conditions. Our findings suggest at least partially distinct subnetworks in the fronto-temporal cortices for morphological and morphosyntactic parsing during the earlier stages of processes (∼400 ms post stimulus onset) and shared neural generators for the later processing stages. [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]

Despite extensive behavioral research on complex word recognition, the neural mechanisms involved in the production of inflections in agglutinative languages, such as Finnish, are still poorly understood. Finnish inflected nouns typically involve morphophonological alternations of the stem (i.e. consonant gradation; CG), which is less common in other languages. Behavioral research on recognition of inflected nouns containing consonant gradation has shown that the number of stem allomorphs results in faster recognition times. To our knowledge, no functional magnetic resonance imaging (fMRI) studies have explicitly investigated consonant gradation in word production. In this study, participants performed covert and overt production tasks during event-related fMRI. Our stimuli comprised real word stems of high and medium frequency as well as pseudoword stems. The stems either included consonant gradation or were non-gradating. Our findings showed that the production of inflected forms containing high frequency stems or CG stems (irrespective of frequency and lexicality) yield enhanced activation of the left inferior frontal and middle frontal gyri (LIFG and MFG, respectively). This suggests that CG stems, that is, stems with more than one allomorph, facilitate lexical lookup, and that the activation of multiple stem allomorphs is reflected in increased recruitment of frontal brain regions. • We examined the effect of stem allomorphy on Finnish inflected word production. • Stem allomorphy increases error rates when producing gradated inflected forms. • Gradated stems cause stronger LIFG/MFG activation compared to non-gradated. • Higher LIFG/MFG activation was present for real stems compared to pseudo-stems. • This robust frontal activation may underpin lexical allomorph access. [ABSTRACT FROM AUTHOR]