Biomedical subjects

N R Zubin

Publications and source records attributed to N R Zubin.

3 recordsLinked to original sources

PubMed2001

Cognitive correlates of mnemonics usage and verbal recall memory in old age.

OBJECTIVES: The objectives of this study were to determine whether minimizing requisite processing resources to learn a word list would differentially improve recall of older adults and to examine the associations between memory and nonmemory cognitive abilities. BACKGROUND: It has been hypothesized that a reduction in general processing resources contributes to age-related declines in memory and other cognitive abilities. METHODS: Twenty-four young adults and 47 older adults were administered two semantically related word lists, one list with words blocked into their categories and the other with categories intermixed. Tests of attention and working memory, language, and abstract reasoning were interspersed with the memory tasks. Participants were classified as young (age range: 17-30 years), young-old (age range: 65-73 years), and old-old (age range: 74-87 years) to compare the effects of list condition (i.e., blocked vs. unblocked) on recall performance. Correlation and regression analyses were used to examine the cognitive correlates of recall performance. RESULTS: Expected age differences in recall performance were observed. Based on the resource-reduction hypothesis of cognitive aging, we hypothesized that the blocked presentation of the to-be-remembered list would minimize processing demands and therefore differentially benefit recall in older elderly participants. Contrary to our prediction, however, the relative benefits of blocked list presentation on recall measures were comparable for young and older participants. Correlations and regression analyses revealed that recall performance was more strongly associated with word finding ability than with working memory or abstract reasoning skills. CONCLUSIONS: Results suggest that level of recall of a semantically related word list and use of semantic clustering as an encoding strategy are associated more strongly with general word finding skills than with processing capacity.

Adolescent↗

PubMed2000

Different brain networks mediate task performance in normal aging and AD: defining compensation.

OBJECTIVE: To determine whether the pathologic mechanisms of AD alter the brain networks subserving performance of a verbal recognition task. BACKGROUND: Functional imaging studies comparing task-related activation in AD patients and controls generally have not used network analysis and have not controlled for task difficulty. METHODS: H2 15O PET was used to measure regional cerebral blood flow in 14 patients and 11 healthy elders during the performance of a serial verbal recognition task under two conditions: low demand, with study list size (SLS) equal to one; and titrated demand, with SLS adjusted so that each subject recognized words at 75% accuracy. The Scaled Subprofile Model was used to identify networks of regionally covarying activity across these task conditions. RESULTS: In the elders, higher SLS was associated with the recruitment of a network of brain areas involving left anterior cingulate and anterior insula (R2 = 0.94; p < 0.0001). Three patients also expressed this network. In the remaining patients, higher SLS was associated with the recruitment of an alternate network consisting of left posterior temporal cortex, calcarine cortex, posterior cingulate, and the vermis (R2 = 0.81, p < 0.001). Expression of this network was unrelated to SLS in the elders and more intact AD patients. CONCLUSIONS: The patients' use of the alternate network may indicate compensation for processing deficits. The transition from the normal to the alternate network may indicate a point where brain disease has irreversibly altered brain function and thus may have important implications for therapeutic intervention.

Aged↗

PubMed2000

Source memory and encoding strategy in normal aging.

Of the memory deficits associated with aging, elders are most impaired at attributing the source to remembered information. Additionally, aging is marked by a decrease in the use of encoding strategies that are thought to enhance the acquisition and retention of information. We examined how manipulating the encoding strategy during acquisition affected item and source memory in 32 young and 68 elderly participants. Elderly participants were dichotomized into young-old and old-old based upon the median age (74 years). Memory was assessed using Word List A from the California Verbal Learning Test (CVLT) and its alternate form. Encoding strategy was manipulated by semantic clustering. For the Blocked List, words were presented grouped into their semantic categories, whereas for the Unblocked List categories were intermixed within the list. Item and source memory judgments were made 20 minutes after the final CVLT recall trial and again one week later. Results revealed a disproportionate decline in source, compared to item memory in the two older groups. Semantic blocking enhanced item memory for the elders, but not for the young. The amount of semantic clustering performed by the elders showed a decline with age and was positively related to source performance. Results also suggest that subtle age-related changes in semantic knowledge may be related to declines in semantic clustering and memory performance.

Adult↗