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PubMed1990

Repetition and verbal STM in transcortical sensory aphasia: a case study.

The repetition performance of a patient (S.T.) with transcortical sensory aphasia is examined in four experiments with particular emphasis on the STM capacities underlying her performance. S.T.'s repetition of word strings exceeding her span (two words) is characterized by good recall of the final items and a strong tendency to lose the initial items in the input string. This pattern contrasts with the serial position effects observed in a phonologically based STM impairment, and it is suggested that a lexical-semantic impairment, also evident in S.T.'s naming and lexical comprehension, contributes to her inability to retain the primacy portions of the input string. Lexical effects obtained in her reproduction of words and nonwords, as well as word strings (Experiments 1 and 2), indicate that under conditions of impaired semantics S.T. is relying on lexical phonological information to repeat. Priming by repeated exposure (Experiment 3) failed to improve her repetition performance, indicating that access to lexical information is brief and dependent on recent phonological input. In Experiment 4, the role of syntactic structure in S.T.'s sentence repetition was examined, and it was shown that syntactic structure affects the recall of order information, but not the number of items recalled. The repetition and verbal STM abilities of this patient, in light of her total language profile, are then evaluated in the context of a language-based view of verbal STM.

Aged↗
PubMed1990

Preserved recognition of familiar personal names in global aphasia.

Recognition of proper and common nouns was compared in four patients diagnosed with global aphasia secondary to ischemic left-hemisphere infarction. For proper noun recognition, subjects matched the spoken or written name of a famous person to a photograph, and for common nouns, subjects were tested on standardized and special word recognition tests. As expected, common noun recognition was severely compromised in the aphasic patients. In contrast, familiar personal names, despite their greater length and complexity, were recognized equally well by aphasic and normal control subjects. The right hemisphere may mediate the ability to recognize personally familiar names, as it may be specialized for establishing personally relevant environmental stimuli.

Aged↗
PubMed1991

A crosslinguistic study of grammaticality judgments in Broca's aphasia.

Crosslinguistic studies of sentence comprehension and production in Broca's aphasia have yielded two complementary findings: (1) grammatical morphology appears to be more impaired than word order principles in every language studied, but (2) the degree to which grammatical morphology is retained by aphasic patients depends upon the "strength" or importance of those morphemes in the patient's premorbid language. In an earlier study comparing violations of word order and agreement, we found that English-speaking Broca's aphasics showed greater sensitivity to errors of ordering than to errors of agreement, providing further evidence for the selective vulnerability of morphology. However, because English is a rigid word order language with a relatively weak inflectional system, it could be argued that word order is resilient to brain damage because it is the strongest source of information in this language. The present study compared the performance of English-speaking Broca's aphasics and normal controls with their Italian counterparts in the same grammaticality judgment experiment. Four predictions relating to our previous work were confirmed. (1) Italian aphasics, like their English-speaking counterparts, showed general preservation of grammatical knowledge and (2) they were able to use this knowledge in an "on-line" fashion. (3) Within each language, Broca's aphasics showed greater impairment in their ability to recognize errors of morphological selection (i.e., agreement) compared with errors made by moving the same words to an incorrect position downstream. Nevertheless (4), crosslinguistic differences observed in previous studies of comprehension and production were also observed in this grammaticality judgment task: a processing advantage for agreement errors in Italian normals and aphasics, and a processing advantage for ordering errors in English normals and aphasics.

Adult↗
PubMed1992

Optic aphasia and the right hemisphere: a replication and extension.

Optic aphasia is a rare, visual modality-specific naming disorder. We describe a patient who developed this disorder subsequent to a left occipital lobe infarction. Like another case that we described previously, this patient performed normally on a variety of tasks assessing the recognition of objects he could not name. Additionally, although he never read aloud a single word, his performance on lexical decision and word comprehension tasks was far better than chance. We suggest that his performance was mediated by a right hemisphere semantic system.

Aged↗
PubMed1986

Studies in artificial aphasia: experiments in processing change.

Computational neurolinguistics, an integrated approach to cognitive modelling of neural processes which may subserve natural language performance, attempts to build computational models that model behavior on two levels: at the neural process level and at the human performance level in its normal state and under pathological conditions. HOPE is one example of such a model. It demonstrates how the design and implementation of such models can provide insights into how a brain-like architecture can produce a behavior as complex as natural language. This paper will briefly describe the neurally motivated or 'natural computation' processes which produce the model's observable and verifiable behavioral results. Experiments with artificially induced aphasia on HOPE will then be described, showing that the results of simulation produce hypothesized patient profiles that are unique. These profiles illustrate the suggested contribution of the computational neurolinguistics research approach as a tool for investigating the breakdown of language performance and its potential contribution to understanding brain function.

Aphasia↗
PubMed1996

Selective language aphasia from herpes simplex encephalitis.

We report the case of a 16-year-old right-handed Chinese/English bilingual patient who developed herpes simplex encephalitis involving the left temporal lobe, with resultant aphasia. His native language was Mandarin, but he had received extensive training in English for 6 years after moving to the United States and was fluent in English. One week after admission, he could not speak, comprehend, repeat, name, read, or write in English, but he had relative preservation of most of these facilities in Mandarin. He could not write in Mandarin, and his syntax was simplified. Two months later, along with intensive bilingual speech therapy, his reading, writing, and naming in English had almost recovered.

Adolescent↗
PubMed2005

[Pasteurella multocida meningo-encephalitis with aphasia in a young adult].

We report the first case of Pasteurella multocida meningo-encephalitis with aphasia in a 28 year-old-patient. The investigations confirmed the diagnosis of bacterial meningitis. But the delay in identification of the organism involved iterative changes of antibiotherapy. The evolution was finally favourable with appropriate antibiotic treatment. The epidemiologic investigation highlighted the responsibility of a patient's cat carrying the same bacterial strain. Finally we discuss the epidemiologic, clinical and therapeutic features of this unusual meningitis.

Adult↗
PubMed2004

Sparing of written production of proper nouns and dates in aphasia.

Aphasia is a total or partial loss of the ability to produce or understand language, usually caused by brain disease or injury. In this case study, the aphasic patient (BMW) has a profound impairment of oral production and a very moderate impairment in comprehension. Several years of informal observation lead to the current study that contrasts written naming of common nouns to written naming of proper nouns and dates. BMW named professional ice hockey players, team logos, and provided birthdays of players with near perfect accuracy and normal rates of production. In contrast, his performance on naming common nouns was only 50% accurate and appeared very laborious. The results of this study thus show a clear preservation of date and proper noun production in contrast to common nouns.

Adult↗
PubMed2004

Semantic, lexical, and phonological influences on the production of verb inflections in agrammatic aphasia.

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.

Adult↗
PubMed2004

Cognitive and cognate-based treatments for bilingual aphasia: a case study.

Two consecutive treatments were conducted to investigate skill learning and generalization within and across cognitive-linguistic domains in a 62-year-old Spanish-English bilingual man with severe non-fluent aphasia. Treatment 1 was a cognitive-based treatment that emphasized non-linguistic skills, such as visual scanning, categorization, and simple arithmetic. Treatment 2 was a lexically based treatment that trained cognates (cross-linguistic word pairs that are similar in meaning and form, such as rosa/rose) and non-cognates (cross-linguistic word pairs with shared meaning but different forms, such as mesa/table). Treatment 1 resulted in modest gains in both Spanish and English. Treatment 2 resulted in improved naming for non-cognates as well as cognates within each language. However, the generalization of gains from Spanish to English was apparent only for cognate stimuli.

Aphasia↗
PubMed2005

Word-category violations in patients with Broca's aphasia: an ERP study.

An event-related brain potential experiment was carried out to investigate on-line syntactic processing in patients with Broca's aphasia. Subjects were visually presented with sentences that were either syntactically correct or contained violations of word-category. Three groups of subjects were tested: Broca patients (N = 11), non-aphasic patients with a right hemisphere (RH) lesion (N = 9), and healthy aged-matched controls (N = 15). Both control groups appeared sensitive to the violations of word-category as shown by clear P600/SPS effects. The Broca patients displayed only a very reduced and delayed P600/SPS effect. The results are discussed in the context of a lexicalist parsing model. It is concluded that Broca patients are hindered to detect on-line violations of word-category, if word class information is incomplete or delayed available.

Adult↗
PubMed2005

The relationship between phonological and morphological deficits in Broca's aphasia: further evidence from errors in verb inflection.

A previous study of 10 patients with Broca's aphasia demonstrated that the advantage for producing the past tense of irregular over regular verbs exhibited by these patients was eliminated when the two sets of past-tense forms were matched for phonological complexity (Bird, Lambon Ralph, Seidenberg, McClelland, & Patterson, 2003). The interpretation given was that a generalised phonological impairment was central to the patients' language deficits, including their poor performance on regular past tense verbs. The current paper provides further evidence in favour of this hypothesis, on the basis of a detailed analysis of the errors produced by these same 10 patients in reading, repetition, and sentence completion for a large number of regular, irregular, and nonce verbs. The patients' predominant error types in all tasks and for all verb types were close and distant phonologically related responses. The balance between close and distant errors varied along three continua: the severity of the patient (more distant errors produced by the more severely impaired patients); the difficulty of the task (more distant errors in sentence completion>reading>repetition); the difficulty of the item (more distant errors for novel word forms than real verbs). A position analysis for these phonologically related errors revealed that vowels were most likely to be preserved and that consonant onsets and offsets were equally likely to be incorrect. Critically, the patients' errors exhibited a strong tendency to simplify the phonological form of the target. These results are consistent with the notion that the patients' relatively greater difficulty with regular past tenses reflects a phonological impairment that is sensitive to the complexity of spoken forms.

Aged↗
PubMed2005

A new empirical angle on the variability debate: quantitative neurosyntactic analyses of a large data set from Broca's aphasia.

Behavioral variation in Broca's aphasia has been characterized as boundless, calling into question the validity of the syndrome-based schema and related diagnostic methods of acquired language disorders. More generally, this putative variability has cast serious doubts on the feasibility of localizing linguistic operations in cortex. We present a new approach to the quantitative analysis of deficient linguistic performance, and apply it to a large data set, constructed from the published literature: Comprehension data of 69 carefully selected Broca's aphasic patients, tested on nearly 6000 stimulus sentences, were partitioned in different ways, and subjected to a series of analyses. While a certain amount of variability is indeed evident in the data, our quantitative analyses reveal a highly robust selective impairment pattern for the group: the patients' ability to analyze syntactic movement is severely compromised, in line with the Trace-Deletion Hypothesis. Further analyses suggest that patients' performance on no-movement sentence types exhibits less variation than on sentences that contain movement. We discuss the clinical and theoretical implications of our results.

Aphasia, Broca↗
PubMed2005

Patterns of comprehension performance in agrammatic Broca's aphasia: a test of the Trace Deletion Hypothesis.

We tested the core prediction of the Trace Deletion Hypothesis (TDH) of agrammatic Broca's aphasia, which contends that such patients' comprehension performance is normal for active reversible sentences but at chance level for passive reversible sentences. We analyzed the comprehension performance of 38 Italian Broca's aphasics with verified damage to Broca's area, who completed sentence-to-picture matching tasks using active and passive reversible sentences as stimuli. The results failed to confirm the predictions made by TDH: only a small minority (15%) performed at chance on passive sentences and better than chance on active sentences. Furthermore, the distribution of the 38 subjects' performance on passive sentences differed from that predicted by the TDH since many more subjects performed at better-than-chance levels than expected. We discuss the implication of these results for claims about the distribution of language processing mechanisms in the brain.

Adult↗
PubMed2005

Clause structure and verb movement in a Greek-English speaking bilingual patient with Broca's aphasia: evidence from adverb placement.

In this paper, we investigate the performance of a Greek-English bilingual patient with Broca's aphasia and mild agrammatism on the placement of CP, MoodP, AspectP, and NegP-related adverbs, labeled specifier-type adverbs, and VP-related adverbs, labeled complement-type adverbs, by means of a constituent ordering task and a grammaticality judgment task. Based on the results derived by means of these two different tasks in both Greek and English, we argue that (i) the CP layer causes great difficulties to aphasic performance in both languages but it is not missing from aphasic grammar, whereas the VP layer remains intact in both languages; (ii) the MoodP, AspectP, and NegP-related adverbs cause more difficulties in English that in Greek. We attribute this to the independent differences between English and Greek that relate to properties of verbal morphology and syntactic head movement.

Adult↗
PubMed2005

Comprehension of passives in Broca's aphasia.

Drai and Grodzinsky have statistically analyzed a large corpus of data on the comprehension of passives by patients with Broca's aphasia. The data come, according to Drai and Grodzinsky, from binary choice tasks. Among the languages that are analyzed are Dutch and German. Drai and Grodzinsky argue that Dutch and German speaking Broca patients should be relatively good (that is, perform above chance) on comprehension of passive sentences, since in Dutch and German passives the relative order of the object and lexical verb is the underlying order and hence no movement takes place. We will demonstrate that both their linguistic arguments and their selection of Dutch data are invalid.

Aphasia, Broca↗
PubMed2005

Category and letter fluency in semantic dementia, primary progressive aphasia, and Alzheimer's disease.

This study examined the impact of various degenerative dementias on access to semantic knowledge and the status of semantic representations. Patients with semantic dementia, primary progressive aphasia, and Alzheimer's disease were compared with elderly controls on tasks of category and letter fluency, with number of words generated, mean lexical frequency and errors recorded. The findings are consistent with the view that category and letter fluency rely on both common and unique cognitive processes. Fluency tasks, with the richness of data obtained, are valuable in distinguishing different dementia syndromes from one another.

Age of Onset↗
PubMed2006

A study of syntactic processing in aphasia I: behavioral (psycholinguistic) aspects.

This paper presents the results of a study of syntactically based comprehension in aphasic patients. We studied 42 patients with aphasia secondary to left hemisphere strokes and 25 control participants. We measured off-line, end-of-sentence, performance (accuracy and reaction time) in two tasks that require comprehension--enactment and sentence-picture matching--and in grammaticality judgment, with whole sentence auditory presentation. We also used sentence-picture matching and grammaticality judgment as tasks in two self-paced listening studies with the same patients to measure on-line performance. In each task and presentation format, we presented sentences that tested the ability to assign and interpret three structural contrasts chosen to examine different basic syntactic operations: actives and passives, subject and object extracted relative clauses, and reflexive pronouns and matched sentences without these elements. We examined these behavioral data to determine patterns of impairment in individual patients and in groups of patients, using correlational analyses, factor analyses, and analyses of variance. The results showed that almost no individual patients had stable deficits referable to the ability to interpret individual syntactic structures, that a variety of structural features contributed to sentence processing complexity both on-line and off-line, that correct responses were associated with normal on-line and errors with abnormal performance, and that the major determinant of performance is a factor that affected performance on all sentence types. The results indicate that the major cause of aphasic impairments of syntactically based comprehension are intermittent reductions in the processing capacity available for syntactic, interpretive, and task-related operations.

Aged↗