Theta-Gamma Coupling and Working Memory in Alzheimer’s Dementia and Mild Cognitive Impairment
Open Access
- 16 April 2018
- journal article
- research article
- Published by Frontiers Media SA in Frontiers in Aging Neuroscience
- Vol. 10, 101
- https://doi.org/10.3389/fnagi.2018.00101
Abstract
Working memory deficits are common among individuals with Alzheimer’s dementia (AD) or mild cognitive impairment (MCI). Yet, little is known about the mechanisms underlying these deficits. Theta-gamma coupling—the modulation of high-frequency gamma oscillations by low-frequency theta oscillations—is a neurophysiologic process underlying working memory. We assessed the relationship between theta-gamma coupling and working memory deficits in AD and MCI. We hypothesized that: (1) individuals with AD would display the most significant working memory impairments followed by MCI and finally healthy control (HC) participants; and (2) there would be a significant association between working memory performance and theta-gamma coupling across all participants. Ninety-eight participants completed the N-back working memory task during an electroencephalography (EEG) recording: 33 with AD (mean ± SD age: 76.5 ± 6.2), 34 with MCI (mean ± SD age: 74.8 ± 5.9) and 31 HCs (mean ± SD age: 73.5 ± 5.2). AD participants performed significantly worse than control and MCI participants on the 1- and 2-back conditions. Regarding theta-gamma coupling, AD participants demonstrated the lowest level of coupling followed by the MCI and finally control participants on the 2-back condition. Finally, a linear regression analysis demonstrated that theta-gamma coupling (β = 0.69, p < 0.001) was the most significant predictor of 2-back performance. Our results provide evidence for a relationship between altered theta-gamma coupling and working memory deficits in individuals with AD and MCI. They also provide insight into a potential mechanism underlying working memory impairments in these individuals.Keywords
Funding Information
- Fondation Brain Canada
- W. Garfield Weston Foundation (RR120070)
This publication has 48 references indexed in Scilit:
- A novel biomarker of amnestic MCI based on dynamic cross-frequency coupling patterns during cognitive brain responsesFrontiers in Neuroscience, 2015
- The functional role of cross-frequency couplingTrends in Cognitive Sciences, 2010
- Compensation and Disease Severity on the Memory-Related Activations in Mild Cognitive ImpairmentBiological Psychiatry, 2010
- Cross-frequency coupling supports multi-item working memory in the human hippocampusProceedings of the National Academy of Sciences of the United States of America, 2010
- Abnormal-induced theta activity supports early directed-attention network deficits in progressive MCINeurobiology of Aging, 2009
- Working memory and control of attention in persons with Alzheimer's disease and mild cognitive impairment.Neuropsychology, 2007
- Neuronal Oscillations in Cortical NetworksScience, 2004
- Persistent activity in the prefrontal cortex during working memoryTrends in Cognitive Sciences, 2003
- Stability of the preclinical episodic memory deficit in Alzheimer's diseaseBrain, 2001
- Synapse loss in frontal cortex biopsies in Alzheimer's disease: Correlation with cognitive severityAnnals of Neurology, 1990