Neural plasticity and treatment-induced recovery of sentence processing in agrammatism

This study examined patterns of neural activation associated with treatment-induced improvement of complex sentence production (and comprehension) in six individuals with stroke-induced agrammatic aphasia, taking into account possible alterations in blood flow often associated with stroke, including delayed time-to-peak of the hemodynamic response function (HRF) and hypoperfused tissue. Aphasic participants performed an auditory verification fMRI task, processing object cleft, subject cleft, and simple active sentences, prior to and following a course of Treatment of Underlying Forms (TUF; Thompson et al., 2003), a linguistically based approach for treating aphasic sentence deficits, which targeted object relative clause constructions. The patients also were scanned in a long-trials task to examine HRFs, to account for any local deviations resulting from stroke, and perfusion images were obtained to evaluate regions of hypoperfused tissue. Region-of-interest (ROI) analyses were conducted (bilaterally), modeling participant-specific local HRFs in left hemisphere areas activated by 12 healthy age-matched volunteers performing the same task, including the middle and inferior frontal gyri, precentral gyrus, middle and superior temporal gyri, and insula, and additional regions associated with complex syntactic processing, including the posterior perisylvian and superior parietal cortices. Results showed that, despite individual variation in activation differences from pre- to post-treatment scans in the aphasic participants, main-effects analyses revealed a general shift from left superior temporal activation to more posterior temporoparietal areas, bilaterally. Time-to-peak of these responses correlated negatively with blood flow, as measured with perfusion imaging.     

Effects of syntactic and semantic argument structure on sentence repetition in agrammatism: Things we can learn from particles and prepositions

Background: Sentence production impairment in aphasia has been attributed to several possible sources that are not mutually exclusive. Linguistic accounts often attribute the difficulty to the complexity of a verb's syntactic and/or semantic argument structure. Cognitive processing accounts emphasise the reduced processing capacity observed in agrammatic aphasia, which in turn has been attributed to reduced semantic short-term memory (STM) or slowed processing.

Aims: In this study we used verb particles and prepositions to investigate effects of differences in syntactic and semantic argument structure on sentence repetition in aphasia. We predicted that verb particles and sentences containing verb-particle constructions would be easier to repeat than prepositions and prepositional transitive sentences, as the former have a less-complex semantic and syntactic argument structure than the latter. Also, semantic and phonological spans were assessed to determine if a reduction in either capacity correlates with repetition ability.

Methods & Procedures: Participants were eight individuals with chronic aphasia. The experimental task was repetition of transitive sentences balanced for length and lexical content containing either verb particles or prepositional object structures. Accuracy of sentence repetition and repetition of verb particles and prepositions within sentences was examined. We calculated the effect of structural complexity on the sentence repetition task as the difference between proportion correct of verb-particle constructions and prepositional transitives. Semantic and phonological STM spans and word spans were also assessed and correlated with this measure of the structural complexity effect on sentence repetition.

Outcomes & Results: Verb-particle sentences were repeated correctly significantly more often than prepositional transitive sentences, and within those sentences verbal particles were repeated correctly significantly more often than prepositions. The effect was strongly associated with fluency scores: it was present in participants with low fluency scores, but not in those with high fluency scores. The phonological, but not the semantic, STM probe span measure correlated with both the difference in accurate repetition of verb-particle and prepositional transitive sentences and the particles and prepositions within those sentences.

Conclusions: Results indicate that differences in argument structure of particle and preposition constructions influence sentence repetition in agrammatic aphasia. The finding that lower fluency scores are associated with poorer performance on more complex structures suggests that this effect is associated with agrammatism. The impact of these structural distinctions between particles and prepositions should be taken into account during development of treatment stimuli for those with agrammatism.     

The relation between syntactic and morphological recovery in agrammatic aphasia: A case study

BACKGROUND: Production of grammatical morphology is typically impaired in agrammatic aphasic individuals, as is their capacity to produce the syntactic structure responsible for licensing that morphology. Whether these two impairments are causally related has been an issue of long-standing debate. If morphological deficits are a side-effect of underlying syntactic ones, as has been claimed (Friedmann & Grodzinsky, 1997; Izvorski & Ullman, 1999), therapy which improves the syntactic deficit should remediate the morphological deficit as well. This paper reports a case study of one individual with such co-occurring impairments and describes their recovery in response to linguistically-motivated treatment targeting his syntactic deficits. METHODS #ENTITYSTARTX00026; PROCEDURES: MD is a 56 year-old male diagnosed with non-fluent Broca's aphasia subsequent to a left-hemisphere CVA, with limited capacity to produce syntactically complex utterances and grammatical morphology. He was enrolled in therapy using Treatment of Underlying Forms (TUF; Thompson & Shapiro, 2005), targeting production of sentences involving Wh-movement (object relative clauses). MD participated in twice-weekly treatment sessions for approximately two months, with daily probes assessing his production of treated and untreated sentence types. In addition, probes assessing his grammatical morphology and sentence production were administered pre- and post-treatment. OUTCOMES #ENTITYSTARTX00026; RESULTS: Pre-treatment scores in tests of grammatical morphology and sentence production indicated deficits in both domains. During treatment, MD successfully acquired production of a variety of sentence with Wh-movement, though this did not generalize to sentences involving a grammatically distinct movement operation (NP-movement). Post-treatment scores also indicated a lack of improvement in production of grammatical morphology. CONCLUSIONS: The dissociation between MD's morphological and syntactic recovery indicates that the recovery of syntactic and morphological processes in aphasia may occur independently. This result is thus surprising under approaches in which morphological and syntactic impairments are strongly and causally related in aphasia, such as the Tree-Pruning Hypothesis (Friedmann, 2001; Friedmann & Grodzinsky, 1997). Further, these results reinforce the conclusion that aphasia treatment can lead to generalization, but only to linguistic material which is in a subset relation to trained structures (Thompson, Shapiro, Kiran & Sobecks, 2003).     

The relation between syntactic and morphological recovery in agrammatic aphasia: A case study

Background: Production of grammatical morphology is typically impaired in agrammatic aphasic individuals, as is their capacity to produce the syntactic structure responsible for licensing that morphology. Whether these two impairments are causally related has been an issue of long‐standing debate. If morphological deficits are a side‐effect of underlying syntactic ones, as has been claimed (Friedmann & Grodzinsky, 1997 Friedmann, N. and Grodzinsky, Y. 1997. Tense and agreement in agrammatic production: Pruning the syntactic tree.. Brain and Language, 56: 397–425. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Izvorski & Ullman, 1999 Izvorski, R. and Ullman, M. 1999. Verb inflection and the hierarchy of functional categories in agrammatic anterior aphasia.. Brain and Language, 69: 288–291.  [Google Scholar]), therapy that improves the syntactic deficit should remediate the morphological deficit as well. This paper reports a case study of one individual with such co‐occurring impairments and describes their recovery in response to linguistically motivated treatment targeting his syntactic deficits.

Methods & Procedures: MD is a 56‐year‐old male diagnosed with non‐fluent Broca's aphasia subsequent to a left‐hemisphere CVA, with limited capacity to produce syntactically complex utterances and grammatical morphology. He was enrolled in therapy using Treatment of Underlying Forms (TUF; Thompson & Shapiro, 2005 Thompson, C. K. and Shapiro, L. P. 2005. Treating agrammatic aphasia within a linguistic framework: Treatment of Underlying Forms.. Aphasiology, 19: 1021–1036. [Taylor & Francis Online], [Web of Science ®] , [Google Scholar]), targeting production of sentences involving Wh‐movement (object relative clauses). MD participated in twice‐weekly treatment sessions for approximately 2 months, with daily probes assessing his production of treated and untreated sentence types. In addition, probes assessing his grammatical morphology and sentence production were administered pre‐ and post‐treatment.

Outcomes & Results: Pre‐treatment scores in tests of grammatical morphology and sentence production indicated deficits in both domains. During treatment, MD successfully acquired production of a variety of sentences with Wh‐movement, although this did not generalise to sentences involving a grammatically distinct movement operation (NP‐movement). Post‐treatment scores also indicated a lack of improvement in production of grammatical morphology.

Conclusions: The dissociation between MD's morphological and syntactic recovery indicates that the recovery of syntactic and morphological processes in aphasia may occur independently in some individuals. The result would not be predicted by approaches in which morphological and syntactic impairments are strongly and causally related in aphasia, such as the tree‐pruning hypothesis (Friedmann, 2001 Friedmann, N. 2001. Agrammatism and the psychological reality of the syntactic tree.. Journal of Psycholinguistic Research, 30: 71–88. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Friedmann & Grodzinsky, 1997 Friedmann, N. and Grodzinsky, Y. 1997. Tense and agreement in agrammatic production: Pruning the syntactic tree.. Brain and Language, 56: 397–425. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). Further, these results reinforce the conclusion that aphasia treatment can lead to generalisation, but only to linguistic material that is in a subset relation to trained structures (Thompson, Shapiro, Kiran, & Sobecks, 2003 Thompson, C. K., Shapiro, L. P., Kiran, S. and Sobecks, J. 2003. The role of syntactic complexity in treatment of sentence deficits in agrammatic aphasia: The complexity account of treatment efficacy (CATE).. Journal of Speech, Language, and Hearing Research, 46: 591–607. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). This research was supported by the NIH under grant DC‐01948 to C. K. Thompson. The authors are grateful to Audrey Holland and two anonymous reviewers for their exceptionally helpful comments and suggestions. The authors are especially grateful to MD and his family for his participation in this research.      

Impaired syntactic comprehension and production in Broca's aphasia: CT lesion localization and recovery patterns

Three of 50 patients with left hemisphere stroke manifested Broca's aphasia associated with deficits in syntactic processing. CT demonstrated anterior infarcts in two patients and a posterior infarct in the third. Two years later, all three patients showed improved syntactic production, but only the patient with the posterior lesion performed significantly above change on a sentence comprehension test requiring syntactic manipulations in the absence of semantic constraints. Prospective investigations combining psycholinguistic analyses and brain imaging techniques may provide empiric data relevant to neurologic models of language and ultimately may contribute to patient prognostication and rehabilitation.     

Comprehension of reversible active and passive sentences in agrammatism

Agrammatism is a language disorder characterised by a morphological and/or syntactic deficit in spontaneous speech. Such deficits are usually associated with comprehension disorders - though it is said that this is not always the case - which result in a certain degree of variability in syntactic, lexical, and morpholexical performance. The purpose of this study is to reconsider the nature of comprehension disorders in agrammatism, to test whether Grodzinsky's Trace Deletion Hypothesis (TDH) can be generalised to all agrammatic patients, and to ascertain whether the pattern of impairment observed in agrammatism differs from that present in fluent aphasic patients. Eleven agrammatic patients were tested by means of a sentence comprehension task comprising simple active and passive reversible sentences. The performance of the agrammatic patients was compared to that of 16 fluent aphasic (10 Wernicke's and 6 conduction) and 10 control subjects. The deficits observed in the agrammatic subjects were compatible with the TDH, but there was also impaired processing of pronouns (elements that are also subject to movement) and a mild deficit on the processing of simple active sentences. The fluent aphasic patients showed a similar pattern of impairment. A logistic regression analysis was then applied to each single case separately, in order to study the homogeneity of the patients' performance within each aphasic subgroup. Of the 11 agrammatic patients, 3 did not show comprehension disorders, 5 had a specific deficit for passive movement, 1 a lexical deficit for pronouns only, and 1 a pattern of impairment compatible with Linebarger et al.'s trade-off theory. The last patient showed a deficit for simple active reversible sentences compatible with damage to the mapping of grammatical functions to thematic roles. Similar patterns of impairment were also found in the fluent aphasic sample. Overall, the results lead to the conclusion that the TDH cannot be generalised to all agrammatic patients, that the mechanism it invokes is not the only source responsible for agrammatic comprehension disorders and also contributes to comprehension disorders in fluent aphasic patients.     

Revisiting the role of Broca's area in sentence processing: syntactic integration versus syntactic working memory

Most previous neuroimaging studies of sentence processing have associated Broca's area with syntactic processing; however, the exact nature of the processes subserved by this brain region is yet not well understood. Although some authors suggest that Brodmann area (BA) 44 of the left inferior frontal gyrus (i.e., Broca's area) is relevant for syntactic integration processes, others claim that it is associated with working memory mechanisms relevant for language processing. To dissociate these two possible functions, the present study investigated hemodynamic responses elicited while participants processed German indirect wh-questions. Activation increases were observed in left BA 44 together with superior temporal areas and right hemispheric homologues for sentences with noncanonical word order, in which a verb argument was dislocated from its canonical position over a relatively long distance. In these sentences, syntactic working memory load was assumed to be greatest. In contrast, no activation increase was elicited by object-initial as opposed to subject-initial sentences that did not differ with respect to working memory costs but with respect to syntactic integration costs. These data strongly suggest that Broca's area plays a critical role in syntactic working memory during online sentence comprehension.     

Dysphagia in acute ischaemic stroke: severity, recovery and relationship to stroke subtype.

Dysphagia in stroke is linked with increased risk of pneumonia, increased length of stay and poorer outcomes. This study followed a cohort of 88 acute ischaemic stroke patients admitted to hospitals in Perth, Western Australia, over 30 days. There were 8/88 deaths (9%). Infections were treated in 25/80 survivors (31%). Presence and severity of dysphagia were measured at 2 and 7 days post-stroke. Respiratory tract infections occurred at significantly higher rates for dysphagics (p<0.05). At 2 days post-stroke, the odds ratio (OR) of chest infection for dysphagics was 1.45 (95% CI=1.07-1.98). Survivors who were "nil by mouth" 2 days post-stroke were significantly more likely to develop pneumonia (p=0.01). At 7 days post-stroke, dysphagics were again more likely to develop pneumonia (p=0.014) with OR=1.77 (95% CI=1.26-2.49). The total anterior circulation infarcts demonstrated more severe and prolonged dysphagia than other stroke subtypes.     

Syntactic processing in agrammatism: Evidence from lexical decision and grammaticality judgement tasks

Abstract

This study explored the ability of aphasic patients to process the same sentences varying in syntactic structure in an on-line task (lexical decision) and an off-line task (grammaticality judgement). Eight agrammatic and six age-matched normal subjects were tested on a lexical decision task which probed ten types of ungrammaticalty (five syntactic and five morphological). Normal subjects showed a sensitivity to ungrammaticalty as demonstrated by a significant increase in reaction time to target words in ungrammatical as compared to grammatical contexts. On a grammaticality judgement task using these same stimuli, normal subjects' performance was near ceiling level. The aphasic subjects failed to show a comparable increase in RT on the lexical decision task. In addition, while the agrammatic aphasics performed above chance, they did not perform as well as expected on the grammaticality judgement task. Results are discussed in terms of the nature of the routines involved in the processing of sentences, particularly with respect of agrammatism.     

Changes in prevalence, severity, and recovery in tardive dyskinesia with age

Advancing age is one of the few factors suggested to predict increased risk of tardive dyskinesias (TDs). By pooling and reanalyzing available epidemiological data, we found strong linear correlations between ages (< 40 to 70 years) and both the prevalences and severity of TD, while neither increased significantly after age 70 years. There was also a strong inverse correlation between rates of spontaneous remission of TD and age (< 30 to > 80 years); TD in those younger than 60 years improved over three times as often as in older patients. These correlations are not readily explained by the duration of previous exposure to neuroleptic drugs and may reflect increased sensitivity of the aging brain to them. These observations support caution in the prolonged use of neuroleptics in patients older than age 50 years but encourage optimism for eventual spontaneous remission of TD in young adults.     

Aphasia rehabilitation with a case of agrammatism: A partial replication

Abstract

A replication of Jones' (1986) therapy study was attempted with a young agrammatic aphasic subject (M.G.) who had demonstrated little improvement in 6 months of traditional treatment directed at improving oral expression. At the end of therapy the patient's verbal output was very limited, and consisted mainly of nouns. He was hypothesized to have a problem accessing verbs and in obtaining access to the meaning relations attached to them. The experimental therapy was directed towards focusing his attention on verbs and on verbal meaning relations in sentences. In particular, the actor, the patient and the locative arguments were emphasized. M.G. was seen 14 and 15 months post-CVA before therapy began. He did not change in oral expression or written language comprehension during this period. Therapy lasted 1 month. M. G.'s performance improved greatly in terms of the number of verbs and the number of verb and argument combinations produced for both control and experimental items. Maintenance of a high performance for the treated and control items was also observed 1 month after therapy had ended. Some improvement in a spontaneous narrative task was also observed immediately after therapy had ended, but it was not maintained after therapy was discontinued for a month. In a control task of written language comprehension the patient's behaviour did not change across the four observation times. These results essentially support those of Jones.     

汉语语法量表及其信度和效度研究

目的 设计一套汉语语法检查量表(Chinese Agrammatism Rattery,CAB)并测试其信度和效度。方法 对46名脑部疾病患者及46例健康受试者进行了CAB测试，计算失语法指数(agrammatism quotient,AgQ)，并与汉语标准化失语检查法(aphasia battery of Chinese,ABC)对比。计算检查者问、检查者内及复测相关系数。结果 左、右大脑半球病变组及对照组CAB各亚项量表分的平均数差异极显著(F＝4．50-18．57，P＜0．05)。左大脑半球病变组各个亚项量表分平均成绩均明显低于右大脑半球病变组(q＝5．63-9．67，P＜0．05)与健康对照组(q＝7．50-9．61，P＜0．01)。量表的复测信度、检查者间信度、检查者内信度均较好(r＝0．991-0．999，P＜0．01)。CAB法的AgQ与ABC比法各指标间呈显著正相关(r＝0．928-0．979，P＜0．01)。结论 CAB具备较好的信度和效度，可以作为定量评定汉语失语症患者语法障碍的工具。