Biomedical subjects

A N Haendiges

Publications and source records attributed to A N Haendiges.

5 recordsLinked to original sources

PubMed1997

Verb retrieval in aphasia. 1. Characterizing single word impairments.

The ability of aphasic patients to produce words from the grammatical classes of nouns and verbs was investigated in tasks that elicited these types of words in isolation. Eleven chronic aphasic patients produced nouns and verbs in picture naming, videotaped scene naming, sentence completion, naming from definition, and oral reading. Comprehension of the meanings of nouns and verbs was tested in word/picture and word/video scene matching, and appreciation of noun/verb grammatical class differences was tested with two metalinguistic tasks. Five patients demonstrated significantly more difficulty producing verbs than nouns, two patients were significantly more impaired producing nouns than verbs, and the remaining four patients showed no difference between the two classes. There was no improvement in verb production when naming actions presented on videotape, suggesting that selective verb impairments are not attributable to conceptual difficulty in identifying actions in static pictures. Selective noun impairments occurred in the context of severe anomia, as reported in previous studies. Selective verb impairments were demonstrated for both agrammatic and fluent (Wernicke) patients, indicating that such deficits are not necessarily associated with the nonfluent and morphologically impoverished production that is characteristic of agrammatism. There was no indication that single word comprehension was affected in these patients in a manner consonant with their production impairments. Results are interpreted in light of current models of lexical organization and processing.

Adult↗

PubMed1997

Verb retrieval in aphasia. 2. Relationship to sentence processing.

Sentence comprehension and production were evaluated for 10 chronic aphasic patients who have been shown to demonstrate one of three patterns in the relative case of retrieval of nouns and verbs. Although these patterns of noun/verb production were not entirely predictable from patients' clinical classifications, they were found here to be significantly correlated with several structural indices of sentence production and with failure to comprehend semantically reversible sentences. Noun/ verb retrieval patterns were not strongly correlated with speech fluency nor with morphological characteristics of sentence production. Patients with relative impairment in the production of verbs were found to rely on high frequency, semantically empty, "light" verbs when producing sentences and to favor simple syntactic structures in which verbs do not require inflections. When forced to produce substantive verbs (in picture and scene descriptions), verb retrieval continued to undermine the production of well-formed sentences for the verb-impaired patients. In addition, two of five such patients also showed some evidence of poor realization of noun arguments for verbs they could not produce. Results are interpreted as indicating multiple contribution to patients' sentence processing impairments, one of which may be selective difficulty retrieving verbs.

Adult↗

PubMed1997

Verb retrieval and sentence processing: dissociation of an established symptom association.

A patient is described with severe anomia who produces verbs significantly better than nouns in action/object naming tasks, but who also has difficulty comprehending and producing semantically reversible sentences. This pattern differs from the frequently-reported association of symptoms involving relative verb/noun retrieval and sentence processing: impaired verb retrieval is typically associated with poor sentence processing, and preserved verb retrieval with spared sentence processing. Brain imaging reveals areas of cerebral ischemia in portions of the, territories supplied by the anterior, middle and posterior cerebral arteries. An earlier ischemic episode and extensive cortical collateral circulation are hypothesized to have contributed to this unusual pattern of left cerebral hemisphere damage. The previously-reported association of symptoms that dissociated in this patient was interpreted as reflecting a hemodynamically-influenced probability of joint involvement of neuroanatomical regions subserving functionally distinct aspects of language processing.

Anomia↗

PubMed1996

Assessing the elements contributing to a "mapping" deficit: a targeted treatment study.

Aphasic patients with excellent comprehension of word meanings frequently fail to understand simple declarative sentences in which either of two nouns could reasonably serve as agent of a transitive action. This study employed targeted treatment of this comprehension problem in a chronic aphasic patient (E.A.) in an attempt to isolate the source or sources of his comprehension failure. Treatment exercises that relied on error feedback in sentence-picture matching or verification initially were not effective. Comprehension of active and passive sentences improved only after both structures were explicitly compared and linked to a picture. Subsequently E.A. maintained consistently accurate interpretation of both sentence types in the treatment exercises as long as the full sentence was available to him. E.A. learned to assign thematic roles using a limited set of cues in the surface structure. Although improvement was reported in untreated sentences, the degree of generalization and the level of performance differed across tasks and appeared to be attributable to cognitive impairments that were not addressed by the treatment. Results are interpreted as evidence suggesting that multiple impairments contribute to failure of sentence comprehension tasks.

Aphasia↗

PubMed1996

Comprehension of reversible sentences in "agrammatism": a meta-analysis.

The functional source(s) of agrammatic aphasic patients' difficulty comprehending semantically reversible active and passive sentences was investigated in a meta-analysis of published sentence/picture matching data from patients with agrammatic production. The analysis revealed approximately equal distributions of three distinct patterns of performance on active and passive voice sentences relative to what would be expected by chance: both structures comprehended better than chance; both structures comprehended no better than chance; active voice sentences comprehended better than chance, while passive voice sentences were comprehended at levels no better than (or worse than) chance. These results are in conflict with explanations of aphasic sentence comprehension failure in which a single pattern of relative performance on active and passive voice structures is asserted to be characteristic of the comprehension of all agrammatic speakers. They also highlight the difficulty of identifying any single causal factor to account for sentence comprehension failure in patients with "agrammatic" sentence production. Results are interpreted with regard to the role of data from aphasic patients in the testing of hypotheses about the organization of normal language processes.

Aphasia, Broca↗