Abstract Details

Title Age-Related Differences in Electrophysiological Activity in Response to Increasing Sensory Degradation and Visual Task Demands

Topic Aging, Dementia, and Behavioral Neurology

Presentation(s) P3 - Poster Session 3 (5:30 PM-6:30 PM)

Poster/Presentation
Number 9-030

Objective

To compare the event-related potential (ERP) responses of young and old adults during a working memory paradigm that parametrically varied visual contrast levels and task demands.

Background Recent longitudinal studies suggest that older adults with sensory deficits are at higher risk for developing cognitive impairment/dementia. It is unclear if the link between sensory and cognitive functioning reflects a common underlying cause or whether sensory deficits directly undermine cognitive processing. Here, we addressed this issue by manipulating sensory degradation and task demands in young and old subjects.

Design/Methods Young (18-32 yo) and old (65-85 yo) adults participated in a visual working memory paradigm while ERPs were recorded. Before each block, participants studied between one and four pairs of faces. One face of each pair was designated as a target. At test, individual faces were shown at one of three contrast levels (100%, 69%, 22%). Participants had to identify each face as a target or non-target (forced choice; 0.5 probability each). The three contrast levels were evenly distributed across trials.

Results In young adults, processing speed, as indexed by P3 latency, decreased across levels of diminishing visual contrast or increasing demand. Compared to their younger counterparts, older adults had prolonged latencies in response to unfiltered stimuli or lower task demands, and failed to generate reliably differentiated responses across levels. Both groups generated smaller responses, as indexed by P3 amplitude, to filtered (69% or 22% contrast) stimuli. Young adults tended to generate larger P3 responses to higher task demands, whereas old adults demonstrated the opposite pattern.

Conclusions Speed of processing was prolonged in old adults, but did not vary reliably across levels of contrast or demand. Filtering/degrading visual stimuli reduced the magnitude of the electrophysiological response to a similar degree in old and young adults. Old adults appear to deplete resources at lower levels of task demand.

Authors/Disclosures
Kirk R. Daffner, MD, FAAN (Brigham & Women's Hospital - Harvard Medical School) PRESENTER	The institution of Dr. Daffner has received research support from Azheimer's Association. The institution of Dr. Daffner has received research support from FUJIFILM.
Adam R. Billig	No disclosure on file
Hura Behforuzi, MD (Brigham and Women'S Hospital)	No disclosure on file
Nicole Feng	No disclosure on file

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