Search PubMed⌕ Search

Biomedical subjects

S Avrutin

Publications and source records attributed to S Avrutin.

6 recordsLinked to original sources
PubMed1999

Comprehension of contrastive stress by Broca's aphasics.

Comprehension of stress as a determiner of reference for pronouns was compared in eight patients with Broca's aphasia (BA) and five age-matched control subjects. The subjects were asked to listen to sentences in which the stressed or unstressed condition of the pronoun was a critical criterion for the establishment of reference. For each sentence, subjects were shown three pictures and asked to point to the correct referent of the pronoun. While the controls were nearly perfect in both the stressed and unstressed conditions, BA patients were significantly worse than normals, showing chance performance in both cases. However, a significant disparity was found in the BA patients' selection of the object NP as the referent under stressed and unstressed conditions, indicating that BA subjects are, indeed, sensitive to the stress patterns of pronouns. It was thus hypothesized that the BA patients' chance performance was the result of an inability to implement their knowledge of stress during the processing of sentences involving discourse-related linguistic operations, such as the establishment of pronoun reference (Grodzinsky, Wexler, Chien, Marakovitz, & Solomon, 1993). To test this hypothesis, a second experiment was conducted in which discourse-related operations were eliminated. In this second experiment, comprehension of stress by the same two groups was compared in tasks involving purely morphosyntactic processes. The contrastive stress patterns of otherwise homophonous compound nouns and adjectival phrases (e.g., BLACKboard, black BOARD), rather than those of pronouns, were examined. In this grammatically "simpler" experiment (i.e., without discourse-related operations), BA subjects scored significantly above chance in their comprehension of sentences involving compound nouns; unexpectedly, however, these same subjects did not show significantly above-chance performance in their comprehension of sentences containing adjectival phrases. Nevertheless, the results obtained in these two experiments seem to support the view that aphasic patients may have a lack of processing capacity, resulting in more errors during the processing of discourse-related linguistic constructions.

Aged↗
PubMed1999

An event-related fMRI study of implicit phrase-level syntactic and semantic processing.

Most neuroimaging studies of language function to date use a block-subtraction paradigm in which images acquired during relatively long periods of target stimuli are compared to those acquired during a control period. These studies typically require an overt response on the part of the subject, usually some type of discrimination or grammatical judgment by button press, or silent word generation. Results from studies of syntactic and semantic processing have generally been compatible with the classical correlation to Broca's area and Wernicke's area, respectively. Recently, functional magnetic resonance imaging (fMRI) studies departing from the block-subtraction paradigm in favor of event-related fMRI paradigms have been reported. We have extended the use of this approach to examine implicit (i.e., without an explicit task on the part of the subject) syntactic and semantic processing at the phrasal level, using visually presented verb phrases. Left BA 44 is more strongly activated for the syntactic condition than the semantic condition. BA 45, 10, and 46 show laterality differences: mostly left-lateralized for the syntactic condition and right-lateralized for the semantic condition. We also find activations of the inferior parietal lobe, consistent with a visual oddball response reported previously, and the anterior cingulate gyrus (BA 32), implicated for attention and memory-related processes in numerous studies.

Adolescent↗
PubMed1996

Comprehension of wh-questions in two Broca's aphasics.

This study investigated comprehension of wh-questions in two Broca's aphasics. Patients were presented for comprehension with two types of wh-questions: questions headed by which and questions headed by who. These two types were chosen because according to recent syntactic analyses they give rise to different types of syntactic "chains." These questions were presented in both subject gap versions (e.g., which cat chased the dog?) and object gap versions (e.g., which cat did the dog chase?). Comprehension of which questions was asymmetric, with subject gap versions comprehended significantly better than object gap versions, the latter yielding chance-level performance. This finding is consistent with previous reports of subject-object asymmetries in comprehension of relative clauses and clefts, as well as active-passive comprehension asymmetries. In contrast, comprehension of who questions was symmetrical over subject gap and object gap versions: Both patients performed equally well (significantly better than chance) on subject gap and object gap who questions. These findings are inconsistent with current formulations of "chain" or "trace"-based theories of agrammatic comprehension which assume a deficit that affects both types of syntactic chains. We suggest that linguistic descriptions of agrammatic comprehension should be limited to deficits involving only one type of chain. We also suggest that there are processing differences underlying the syntactic distinctions between which-type and who-type questions and that this may account for different patterns of comprehension on these and other constructions.

Aged↗
PubMed1995

Representation, referentiality, and processing in agrammatic comprehension: two case studies.

A number of investigators have argued that agrammatic comprehension, the pattern of sentence comprehension often associated with Broca's aphasia, can be characterized in terms of a representational disruption in one or another module of the normal grammar. In this study, these proposals are reviewed and their adequacy is examined in light of two case studies of agrammatic comprehension. In particular, we present data from sentences that have composed the core of the agrammatic comprehension pattern, as well as data from three different classes of sentences including comprehension of the matrix clause of center-embedded relative constructions, pronoun and anaphor dependencies, and Wh-questions. Our conclusion is that none of the existing representational models provides a fully adequate account of the data, and we propose some alternative approaches that distinguish between referential and nonreferential elements and potential processing differences between the two.

Aged↗