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Abstract Details

What’s changing from normal aging to pathological aging during semantic memory retrieval: insights from EEG oscillations
Aging, Dementia, Cognitive, and Behavioral Neurology
S8 - Behavioral and Cognitive Neurology (4:30 PM-4:42 PM)

Semantic memory remains relatively stable with normal cognitive aging and its decline might be an indicator of a neurodegenerative disease. Studying EEG correlates of semantic retrieval could provide early markers of neurodegeneration.

To examine differences in EEG oscillations between normal cognitive aging versus pathological aging during semantic memory retrieval.

Twenty-nine young adults (YA: 21.3 years), 22 healthy aging adults (HA: 63.9 years), and 20 patients with mild cognitive impairment (MCI: 67.8 years) participated. We recorded EEG while one completed a semantic task in which one was asked to judge whether two words led to retrieval of an object (retrieval, R) or not (non-retrieval, NR). Using Morlet wavelet time-frequency decomposition, event-related power changes within theta (4-8Hz), alpha (8-12Hz), low-beta (12-20 Hz), and high-beta (20-30 Hz) EEG frequency bands were measured. Power data contrasting R vs NR trials were analyzed separately to compare (1) YA versus HA (normal aging effects) and (2) HA versus MCI (pathological aging effects) using independent t-tests (permutations N = 2000; significance level at FDR of 0.05).

For normal aging effects, though no behavioral differences between the normal groups, we found theta (NR > R, 628-701 ms) and alpha (R < NR, 555-591 ms) power differences only in YA, and a high-beta power difference (NR > R, 444-481 ms) only in HA. For pathological aging effects, accuracy was reduced in MCI. Two EEG differences were found: a different pattern of high-beta power differences (224-261 ms) in MCI (NR > R) than HA (R > NR), and a low-beta power difference (R > NR, 444-481 ms) only in HA.

Brain responses transition from slower (alpha, theta) to faster (beta) activity with aging during semantic memory retrieval. Retrieval accuracy declines and patterns of neural oscillation change with MCI. The findings have implications for early detection of pathological aging.

Hsueh-Sheng Chiang, MD, PhD (University of Texas Southwestern Medical Center)
The institution of Dr. Chiang has received research support from NIH/NIDCD. The institution of Dr. Chiang has received research support from Texas Alzheimer's Research and Care Consortium.
Elizabeth Lydon, Other Ms. Lydon has nothing to disclose.
John Hart, MD (The University of Texas At Dallas) The institution of Dr. Hart has received research support from Department of Defense.
Michael Kraut, MD,PhD Dr. Kraut has nothing to disclose.
Raksha Anand Mudar No disclosure on file