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Wernicke's 1903 case pure agraphia : an enigma for classical models of written language processing
(1996)
Recently, neurolinguistic explanations informed by linguistic theory have been proposed to account for spontaneous and elicited agrammatic speech production. These are either formulated in terms of impaired representations or they refer to impaired processing. Both have in common that they assume severe disorders of question production due to vulnerability of the left periphery of sentence structures in the representational account, of verb movement in the processing account. We report the results of question elicitation and spontaneous speech analysis in eight chronic German agrammatic speakers. The results indicate that there is not one homogeneous agrammatic pattern, but that the data reveal double dissociations which cannot be accounted for by the unitary explanations of agrammatism which are presently available. An alternative explanation will be provided which-in contrast to the representational account not only refers to global hierarchically organized nodes but relies on linguistic differences within these nodes. The assumption that they can be differentially affected in agrammatism can account for the observed patterns. (c) 2005 Elsevier Ltd. All rights reserved
Most studies investigating the impact of literacy on oral language processing have shown that literacy provides phonological awareness skills in the processing of oral language. The implications of these results on aphasia tests could be significant and pose questions on the adequacy of such tools for testing non-literate individuals. Aiming at examining the impact of literacy on oral language processing and its implication on aphasia tests, this study tested 12 non-literate and 12 literate individuals with a modified Amharic version of the Bilingual Aphasia Test (Paradis and Amberber, 1991, Bilingual Aphasia Test. Amharic version. Hillsdale, NJ: Lawrence Erlbaum.). The problems of phonological awareness skills in oral language processing in non-literates are substantiated. In addition, compared with literate participants, non-literate individuals demonstrated difficulties in the word/sentence-picture matching tasks. This study has also revealed that the Amharic version of the Bilingual Aphasia Test may be viable for testing Amharic-speaking non-literate individuals with aphasia when modifications are incorporated.
Tense and Agreement dissociations in German agrammatic speakers : Underspecification vs. hierarchy
(2005)
The aim of the present paper was to investigate whether German agrammatic production data are compatible with the Tree-Pruning-Hypothesis (TPH; Friedmann & Grodzinsky, 1997). The theory predicts unidirectional patterns of dissociation in agrammatic production data with respect to Tense and Agreement. However, there was evidence of a double dissociation between Tense and Agreement in our data. The presence of a bidirectional dissociation is incompatible with any theory which assumes a hierarchical order between these categories such as the TPH or other versions thereof (such as Lee's, 2003 top-down hypothesis). It will be argued that the data can better be accounted for by relying on newer linguistic theories such as the Minimalist Program (MP, Chomsky, 2000), which does not assume a hierarchical order between independent syntactic Tense and Agreement nodes but treats them as different features (semantically interpretable vs. uninterpretable) under a single node. (c) 2005 Elsevier Inc. All rights reserved
Comprehension of non-canonical sentences can be difficult for individuals with aphasia (IWA). It is still unclear to which extent morphological cues like case marking or verb inflection may influence IWA's performance or even help to override deficits in sentence comprehension. Until now, studies have mainly used offline methods to draw inferences about syntactic deficits and, so far, only a few studies have looked at online syntactic processing in aphasia. We investigated sentence processing in German-speaking IWA by combining an offline (sentence-picture matching) and an online (eye-tracking in the visual-world paradigm) method. Our goal was to determine whether IWA are capable of using inflectional morphology (number-agreement markers on verbs and case markers in noun phrases) as a cue to sentence interpretation. We report results of two visual-world experiments using German reversible SVO and OVS sentences. In each study, there were eight IWA and 20 age-matched controls. Experiment 1 targeted the role of unambiguous case morphology, while Experiment 2 looked at processing of number-agreement cues at the verb in caseambiguous sentences. IWA showed deficits in using both types of morphological markers as a cue to non-canonical sentence interpretation and the results indicate that in aphasia, processing of case-marking cues is more vulnerable as compared to verbagreement morphology. We ascribe this finding to the higher cue reliability of agreement cues, which renders them more resistant against impairments in aphasia. However, the online data revealed that IWA are in principle capable of successfully computing morphological cues, but the integration of morphological information is delayed as compared to age-matched controls. Furthermore, we found striking differences between controls and IWA regarding subject-before-object parsing predictions. While in case-unambiguous sentences IWA showed evidence for early subjectbefore-object parsing commitments, they exhibited no straightforward subject-first prediction in case-ambiguous sentences, although controls did so for ambiguous structures. IWA delayed their parsing decisions in case-ambiguous sentences until unambiguous morphological information, such as a subject-verbnumber-agreement cue, was available. We attribute the results for IWA to deficits in predictive processes based on morphosyntactic cues during sentence comprehension. The results indicate that IWA adopt a wait-and-see strategy and initiate prediction of upcoming syntactic structure only when unambiguous case or agreement cues are available. (C) 2015 Elsevier Ltd. All rights reserved.
Rapid recovery of aphasia and deep dyslexia after extensive left-hemisphere damage in childhood
(1994)
Background: While the role of the right hemisphere (RH) in prosodic processing is prominent, research on the perception of lexical tones has shown that left hemisphere damaged (LHD) patients are more impaired than right hemisphere damaged (RHD) patients. Dichotic listening and imaging studies with healthy speakers of tone languages demonstrate that at least at the phonemic and lexical level, prosody is processed in the left hemisphere (LH) when the variations in pitch are phonemically distinctive. There is no report available yet on the perceptual discrimination of a Bantu language in patients after unilateral brain damage. Aims: We addressed the question of how well Shona aphasic patients and right hemisphere damaged patients perceive pitch contrasts in Shona lexical words and also in their homologous low-pass filtered counterparts. We also sought to discover the validity of the current hypotheses on hemispheric lateralisation particularly the hypothesis on hemispheric lateralisation based on language function to account for the Shona data. Methods Procedures: A total of 7 LHD and 7 RHD patients and 14 healthy controls participated in two discrimination tasks that examined perception of lexical tone in (a) bisyllabic Shona words and (b) low-pass filtered stimuli. In both tasks the participants were tasked with judging the pitch as the same or different in 120 bisyllabic words and 120 low-pass filtered stimuli. Outcomes Results: The results demonstrated that the tonal discrimination of the LHD group was more reduced in comparison to the RHD group and control participants. However, the performance of the RHD patients was not error free relative to the control participants, although significantly better than the LHD patients in both tasks. Conclusions: At least for the phonemic and lexical levels, brain damage to the dominant hemisphere results in lexical tone impairment for LHD patients, and cognitive load processing results in a subdued but good performance for RHD patients. The LH is therefore dominant for processing tone when it is lexically distinctive.
Many agrammatic aphasics have a specific syntactic comprehension deficit involving processing syntactic transformations. It has been proposed that this deficit is due to a dysfunction of Broca's area, an area that is thought to be critical for comprehension of complex transformed sentences. The goal of this study was to investigate the role of Broca's area in processing canonical and non-canonical sentences in healthy subjects. The sentences were presented auditorily and were controlled for task difficulty. Subjects were asked to judge the grammaticality of the sentences while their brain activity was monitored using event-related functional magnetic resonance imaging. Processing both kinds of sentences resulted in activation of language-related brain regions. Comparison of non-canonical and canonical sentences showed greater activation in bilateral temporal regions; a greater activation of Broca's area in processing antecedent-gap relations was not found. Moreover, the posterior part of Broca's area was conjointly activated by both sentence conditions. Broca's area is thus involved in general syntactic processing as required by grammaticality judgments and does not seem to have a specific role in processing syntactic transformations. (C) 2004 Wiley-Liss, Inc
Morphological processing in Italian agrammatic speakers : eight experiments in lexical morphology
(1996)
Modality-specific anomias
(1997)
Background: The issue of production and perception of lexical tone in patients with brain lesions has been investigated mainly through East Asian languages and Norwegian. The present study investigated the lateralisation of lexical tone in Shona, a Bantu language. Van Lancker (1980) proposed a continuum scale of the levels of functional pitch in the speech signal. According to the functional lateralisation account (FLH), the left hemisphere (LH) is associated with highly structured pitch contrasts, such as phonological tone, whereas the right hemisphere (RH) is specialised for the least structured pitch functions cueing emotional and personal information. The extant data show that the ability to produce and identify lexical tone is frequently more impaired as a result of lesions to the LH than RH lesions.
Aims: The present investigation focused on the lateralisation of lexical tone in Shona speakers. The study sought to validate if the scale of hemispheric lateralisation as proposed by Van Lancker (1980) is also valid for Shona, a Bantu language.
Methods & Procedures: We examined five LH damaged (LHD) patients and five RH (RHD) damaged patients using a confrontational picture-naming task and a lexical tone identification task of Shona lexical tone. The first experiment investigated the ability of LHD patients and RHD patients to identify Shona lexical tone in 60 disyllabic minimal pairs. The second experiment examined the ability of Shona brain-damaged patients to produce lexical tone using a confrontational picture-naming task with 120 lexical items.
Outcomes & Results: We observed a dissociation in the performance of both the LHD and RHD patients in the two tasks. Both groups were impaired in the tone identification task relative to the non-brain-damaged controls. However, RHD patients performed significantly better than the LHD patients in the tone identification task. On the other hand, both LHD and RHD groups were equally impaired in the tone production task in comparison to the controls.
Conclusions: The discrepancy in the production and perception of Shona lexical tone for this group of brain-damaged patients shows that, although the two modes are related, they do not always get disrupted at the same level after brain damage. The results from the tone identification task suggest to a certain extent that the FLH is also valid for Shona. In order to account for all the data there is need to carefully consider alternative accounts like the acoustic cue hypothesis (Van Lancker & Sidtis, 1992).
LeMo, an expert system for single case assessment of word processing impairments in aphasic patients
(1997)
LeMo - an expert-system for the assessment of lexical and morphological impairments in aphasia
(1995)
Background: In addition to the canonical subject-verb-object (SVO) word order, German also allows for non-canonical order (OVS), and the case-marking system supports thematic role interpretation. Previous eye-tracking studies (Kamide et al., 2003; Knoeferle, 2007) have shown that unambiguous case information in non-canonical sentences is processed incrementally. For individuals with agrammatic aphasia, comprehension of non-canonical sentences is at chance level (Burchert et al., 2003). The trace deletion hypothesis (Grodzinsky 1995, 2000) claims that this is due to structural impairments in syntactic representations, which force the individual with aphasia (IWA) to apply a guessing strategy. However, recent studies investigating online sentence processing in aphasia (Caplan et al., 2007; Dickey et al., 2007) found that divergences exist in IWAs' sentence-processing routines depending on whether they comprehended non-canonical sentences correctly or not, pointing rather to a processing deficit explanation. Aims: The aim of the current study was to investigate agrammatic IWAs' online and offline sentence comprehension simultaneously in order to reveal what online sentence-processing strategies they rely on and how these differ from controls' processing routines. We further asked whether IWAs' offline chance performance for non-canonical sentences does indeed result from guessing. Methods Procedures: We used the visual-world paradigm and measured eye movements (as an index of online sentence processing) of controls (N = 8) and individuals with aphasia (N = 7) during a sentence-picture matching task. Additional offline measures were accuracy and reaction times. Outcomes Results: While the offline accuracy results corresponded to the pattern predicted by the TDH, IWAs' eye movements revealed systematic differences depending on the response accuracy. Conclusions: These findings constitute evidence against attributing IWAs' chance performance for non-canonical structures to mere guessing. Instead, our results support processing deficit explanations and characterise the agrammatic parser as deterministic and inefficient: it is slowed down, affected by intermittent deficiencies in performing syntactic operations, and fails to compute reanalysis even when one is detected.
In his short paper of 1886, the neogrammarian linguist Delbruck sketches his views on normal language processing and their relevance for the interpretation of some of the symptoms of progressive anomic aphasia. In particular, he discusses proper name impairments, verb and abstract noun superiority and the predominance of semantically related errors. Furthermore, he suggests that part of speech, morphology and word order may be preserved in this condition. This historical document has been lost in oblivion but the original ideas and their relevance for contemporary discussions merit a revival.