Graduation Year


Date of Submission


Document Type

Open Access Senior Thesis

Degree Name

Bachelor of Arts



Second Department

W.M. Keck Science Department

Reader 1

Catherine Reed

Reader 2

Alison Harris

Terms of Use & License Information

Terms of Use for work posted in Scholarship@Claremont.

Rights Information

2023 Heather M Shipley


Neurodegenerative disease associated with aging can have devastating effects on cognitive function, but of interest is how healthy aging affects cognitive and neural function. One measure of neural function associated with aging and cognitive decline is alpha-band oscillations (8-13 Hz) in electroencephalography data (EEG). Alpha-band oscillations are thought to play a role in complex cognitive function and network coordination through inhibitory processes indexed via alpha suppression. We examined whether the aperiodic component of neural activity, a marker of neural noise, influences findings of age-related differences in alpha-band oscillatory activity. In this study, we examined how aging and increased cognitive load influenced peak alpha frequency (PAF) and alpha suppression during resting-states and task-related states. Younger adults (YA; n=32, M=20.0, 18-24 yrs.) and older adults (OA; n=28, M=76.7, 64-88 yrs.) performed tasks with increasing cognitive load: Eyes Closed (3 min), Eyes Open (3 min), and a Visual Oddball Task. We recorded neural activity using a 64-channel EEG system and calculated PAF, Center of Gravity (CoG), and Peak Alpha Power. Replicating recent literature, we found that YAs have higher PAF/CoG and greater peak alpha power than OAs. We also documented increased PAF/CoG with increased cognitive load, but this shift does not interact with age. Finally, we calculated alpha suppression with and without the aperiodic component. When the aperiodic component was included, we found that age interacted with load to affect alpha suppression. However, when the aperiodic component was removed, only the main effects of age and load remained, eliminating age-related interactions. These results suggest that the inclusion of the aperiodic component may lead to the overestimation of the true effects of age on alpha power. In sum, age affects peak alpha frequencies and overall power in alpha-band oscillations, but it does not interact with changes in alpha corresponding to increased cognitive load.

Available for download on Thursday, May 01, 2025