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J Mickanin

Publications and source records attributed to J Mickanin.

10 recordsLinked to original sources
PubMed1997

Lexical acquisition in probable Alzheimer's disease.

Patients with probable Alzheimer's disease (pAD) were exposed to a new verb in a naturalistic fashion. We probed their knowledge of the word's semantic and grammatical characteristics for several minutes following this exposure, and compared this with their performance on parallel measures assessing known words. Significant differences were seen between pAD patients and controls in the acquisition of the new verb's semantic meaning and its argument structure, but pAD patients did not differ from controls in the acquisition of the new word's grammatical form class. Individual patient analyses demonstrated parallel deficits restricted to the semantic meaning and argument structure of the new word and known words in several pAD patients, suggesting that a selective language impairment contributed to their word learning deficit. This pattern is consistent with an intimate relationship between semantic meaning and argument structure in semantic memory. Other pAD patients had difficulty learning about all aspects of the new word, despite good performance with known words, suggesting that compromised memory may have limited their lexical acquisition.

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PubMed1996

Verb comprehension deficits in probable Alzheimer's disease.

Studies of lexical comprehension in probable Alzheimer's disease (pAD) have focused almost exclusively on nouns. In the following preliminary study, we examined whether lexical comprehension for verbs is also impaired in 25 pAD patients. The semantic meaning of motion verbs, cognition verbs, and perception verbs was assessed with a triadic comparison task. Structural meaning associated with these verbs was evaluated by asking the patients to judge the coherence of sentence frames that accept these verbs naturally or awkwardly. We found that pAD patients are significantly impaired at identifying semantic relations among verbs. pAD patients also encountered significantly more difficulty judging the coherence of sentences than control subjects. Correlation and regression analyses demonstrated that semantic characteristics of verbs are projected from the verb's sentence frames in control subjects, but there was minimal evidence for such a structural-semantic relationship in pAD. We consider several possible explanations for our preliminary observations of an impairment that has consequences for processing both semantic and structural aspects of verb meaning.

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PubMed1996

Anomaly judgments of subject-predicate relations in Alzheimer's disease.

Claims that patients with probable Alzheimer's disease (AD) have semantic memory difficulty have received equivocal support. A common assumption has been that defining or core information determines the truth value of word meaning on measures requiring semantic memory such as category membership judgments or confrontation naming, but this assumption may not be valid. In the present study, we assessed the comprehension of subject-predicate sentences independent of their truth value by asking AD patients to judge the coherence of statements such as "The tulip is tall" or "*The tulip is jealous." We found that AD patients are significantly more impaired than controls at judging the coherence of these simple subject-predicate sentences. Moreover, AD patients were more successful at judging the coherence of statements that contain attributes with a narrow scope of reference compared to attributes with a broad scope of reference. These findings support the hypothesis that AD patients have a semantic memory impairment and suggest a specific deficit processing the network of semantic relations underlying word meaning in semantic memory.

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PubMed1996

Freehand drawing impairments in probable Alzheimer's disease.

We evaluated freehand picture production of familiar objects in patients with probable Alzheimer's disease. The overall recognizability of their drawings was significantly compromised. Error analyses revealed the production of category violations and the frequent inclusion of incorrect features in a picture that were borrowed from semantically related objects, suggesting difficulty distinguishing between items with overlapping features sets in semantic memory. Analyses of individual patient drawing profiles also revealed that some patients are disproportionately compromised in expressing a particular perceptual feature, implicating difficulty at the level of perceptual processing. Regression analyses demonstrated the contribution of limited visual attentional resources. We conclude that impaired freehand drawing in probable Alzheimer's disease is multifactorial in nature.

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PubMed1995

An aspect of sentence processing in Alzheimer's disease: quantifier-noun agreement.

We assessed sentence processing in Alzheimer's disease (AD) with measures of sentence-picture matching, grammaticality judgments of sentences, and sentence completion. The results demonstrated significant and consistent difficulty with a grammatical feature of sentences on all three experiments. This impairment could not be explained by factors such as sentence length, dementia severity, or a short-term memory deficit and was independent of difficulty interpreting the meanings of words. We hypothesize that AD patients are impaired at appreciating the conceptual relations that underlie certain grammatical features of sentences.

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PubMed1995

Phonologic processing deficits in Alzheimer's disease.

We investigated phonologic production in patients with mild to moderate Alzheimer's disease (AD) on a repetition task. AD patients produced significantly more speech errors than age-matched controls. AD patients' errors, unlike those of controls, resulted in the transformation of real words into pseudowords, occurred disproportionately in word-initial positions, and were not influenced by the phonologic environment. This pattern of errors suggests a lexical phonologic retrieval deficit in AD.

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PubMed1994

Picture comprehension in probable Alzheimer's disease.

Patients with probable Alzheimer's disease (pAD) are frequently said to be compromised at a semantic level of picture comprehension. In order to test this hypothesis, pAD patients were asked to judge whether pictures are instances of a familiar superordinate category ("vegetable"). The targets (e.g., corn) varied in their representativeness, and the foils were either "coherent" items that were not target exemplars (e.g., apple, chair) or "anomalous" items displaying specific features that disqualified the stimuli as target exemplars (e.g., striped carrot). We also asked patients to judge a comparable set of words to determine whether difficulty appreciating pictures is material-specific. pAD patients were impaired at judging target pictures and a subset of picture foils, according to group-wide analyses, although they also encountered some difficulty judging the category membership of words. Individual patient analyses revealed that some patients were equally impaired at judging pictures and words. In particular, one subgroup experienced significant difficulty distinguishing coherent foils related to the target from true exemplars, and this occurred when the foils were presented as either pictures or words. An item-by-item analysis revealed highly concordant difficulty judging the same concepts expressed as either pictures or words in these patients. A material-specific deficit was evident in other pAD patients that resulted in selectively compromised picture judgments, including essentially all types of picture foils. We discuss these profiles of picture comprehension difficulty and conclude that deficits in understanding pictures in pAD may be due to semantic or perceptual types of impairment.

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