Biomedical subjects

Lynda Ken

Publications and source records attributed to Lynda Ken.

3 recordsLinked to original sources

PubMed2007

Utility of behavioral versus cognitive measures in differentiating between subtypes of frontotemporal lobar degeneration and Alzheimer's disease.

We hypothesized that a modified version of the Frontal Behavioral Inventory (FBI-mod), along with a few cognitive tests, would be clinically useful in distinguishing between clinically defined Alzheimer's disease (AD) and subtypes of frontotemporal lobar degeneration (FTLD): frontotemporal dementia (dysexecutive type), progressive nonfluent aphasia, and semantic dementia. We studied 80 patients who were diagnosed with AD (n = 30) or FTLD (n = 50), on the basis of a comprehensive neuropsychological battery, imaging, neurological examination, and history. We found significant between-group differences on the FBI-mod, two subtests of the Rey Auditory Verbal Learning Test (verbal learning and delayed recall), and the Trail Making Test Part B (one measure of 'executive functioning'). AD was characterized by relatively severe impairment in verbal learning, delayed recall, and executive functioning, with relatively normal scores on the FBI-mod. Frontotemporal dementia was characterized by relatively severe impairment on the FBI-mod and executive functioning in the absence of severe impairment in verbal learning and recall. Progressive nonfluent aphasia was characterized by severe impairment in executive functioning with relatively normal scores on verbal learning and recall and FBI-mod. Finally, semantic dementia was characterized by relatively severe deficits in delayed recall, but relatively normal performance on new learning, executive functioning, and on FBI-mod. Discriminant function analysis confirmed that the FBI-mod, in conjunction with the Rey Auditory Verbal Learning Test, and the Trail Making Test Part B categorized the majority of patients as subtypes of FTLD or AD in the same way as a full neuropsychological battery, neurological examination, complete history, and imaging. These tests may be useful for efficient clinical diagnosis, although progressive nonfluent aphasia and semantic dementia are likely to be best distinguished by language tests not included in standard neuropsychological test batteries.

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PubMed2006

Neural correlates of modality-specific spatial extinction.

Sites of lesions responsible for visual, tactile, and/or motor extinction have not been clearly identified. We sought to determine the frequency of extinction in various modalities immediately after acute ischemic stroke, the rate of co-occurrence of extinction across modalities, and areas of infarct and/or hypoperfusion associated with each modality of extinction. A total of 148 patients with right supratentorial stroke were studied. In Study 1, 88 patients without hemiplegia, hemianesthesia, or visual field cuts were tested within 24 hours of onset for visual, tactile, and motor extinction, and underwent magnetic resonance diffusion and perfusion imaging. Associations between modality of extinction and areas of neural dysfunction (hypoperfusion/infarct) were identified. Of the 88 patients, 19 had only tactile extinction, 8 had only visual extinction, 12 had only motor extinction, 14 had extinction in two or more modalities, and 35 had no extinction. Tactile extinction was associated with neural dysfunction in the inferior parietal lobule; visual extinction was associated with dysfunction in the visual association cortex; and motor extinction was associated with neural dysfunction in the superior temporal gyrus. In Study 2, data from 60 patients who were excluded from Study 1 because of motor deficits were analyzed in the same way to determine whether frontal lesions contributed to visual or tactile extinction. Results again demonstrated that tactile extinction is associated with inferior parietal dysfunction, and visual extinction is associated with dysfunction of the visual association cortex. Potential accounts of the results, based on the "hemisphere rivalry" model of extinction and the limited attentional capacity model, are considered.

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PubMed2004

Deterioration of naming nouns versus verbs in primary progressive aphasia.

Disproportionate impairment of naming nouns versus verbs and the opposite pattern have been reported in cases of focal brain damage or degenerative disease, indicating that processing of nouns and verbs may rely on different brain regions. However, it has not been clear whether it is the spoken word forms or the meanings (or both) of nouns and verbs that depend on separate neural regions. We tested oral and written naming of nouns and verbs, matched in difficulty, in patients with nonfluent primary progressive aphasia (nonfluent PPA; n = 15), fluent primary progressive aphasia (fluent PPA; n = 7), and amyotrophic lateral sclerosis with frontotemporal dementia (ALS-FTD; n = 6). Patients with nonfluent PPA and ALS-FTD, both individually and as groups, were significantly more impaired on verb naming than on noun naming and significantly more impaired on oral naming than written naming. Patients with fluent PPA showed the opposite pattern for both word class and modality, significantly more impaired naming of nouns versus verbs and significantly more impaired written versus oral naming. Results indicate that separate regions of the brain are essential for access to oral and written word forms of verbs and nouns, and that these neural regions can be differentially damaged in separate forms of PPA.

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