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Alpha rhythms in mild dements during visual delayed choice reaction time tasks: a MEG study
Claudio Babiloni1, Emanuele Cassetta, Paola Chiovenda
1Dipartimento di Fisiologia Umana e Farmacologia, Università La Sapienza, P.le Aldo Moro 5, 00185 Roma, Italy. claudio.babiloni@uniroma1.it
Brain Research Bulletin
|May 3, 2005
Summary
Simple delayed response tasks are challenging for early dementia patients, impacting brain activity. Alzheimer's disease (AD) and vascular dementia (VaD) patients showed delayed and stronger alpha rhythm responses, indicating abnormal cortical activation.
Area of Science:
- Neuroscience
- Cognitive Neurology
Background:
- Dementia, including Alzheimer's disease (AD) and vascular dementia (VaD), impairs cognitive functions.
- Magnetoencephalography (MEG) measures brain activity, specifically alpha rhythms (6-12 Hz), which are sensitive to cognitive load.
Purpose of the Study:
- To investigate the effects of simple delayed response tasks on magnetoencephalographic (MEG) midline alpha rhythms in early dementia.
- To assess if these tasks reveal differences in cortical activation (event-related desynchronization, ERD) between dementia patients and normal controls.
Main Methods:
- Recruited mild AD (15) and VaD (10) patients, alongside young (18) and elderly (22) normal controls.
- Administered two delayed response tasks involving stimulus memorization and motor response.
- Analyzed event-related desynchronization (ERD) of midline alpha rhythms (6-12 Hz) correlated with correct behavioral responses.
Main Results:
- Dementia patients (AD and VaD) exhibited lower behavioral performance compared to normal subjects.
- A subset of dementia patients showed later peak latency for alpha ERD compared to young controls, similar to elderly controls.
- Dementia patients displayed stronger amplitude of alpha ERD compared to normal subjects, suggesting altered cortical activation.
Conclusions:
- Simple delayed response tasks pose significant difficulty for individuals with early-stage dementia.
- The observed abnormal alpha ERD (delayed latency and increased amplitude) in dementia patients reflects difficulties in cognitive processing and altered cortical activation patterns.