Cholinergic modulation of spontaneous MEG activity: implications for Alzheimer's disease

摘要

Scopolamine, a central muscarinic receptor antagonist, produces temporary cognitive impairments partially resembling those observed in Alzheimer's disease (AD). Electrophysiologically AD is known to be associated with a significant reduction of alpha power and an increase in theta and delta power in EEG. In order to test the sensitivity of the brain activity power spectrum to changes in cholinergic transmission, we evaluated quantitative magnetoencephalogram (MEG) in eight aged healthy subjects (59-80 years) after intravenous injection of scopolamine and glycopyrrolate, the latter being a peripheral muscarinic antagonist. Scopolamine administration resulted in a significant reduction of alpha activity (8-13Hz) as compared with the glycopyrrolate condition. This result was accompanied by a peak frequency shift towards slower waves after scopolamine infusion. The MEG changes induced by scopolamine were the most prominent in parietal and occipital regions. In conclusion, spontaneous cortical activity at the alpha frequency range appears to be modulated by the cholinergic system. MEG may provide a tool for monitoring brain dynamics in dementia, including AD.