Centre for Neuroscience, Indian Institute of Science, Bangalore, 560012, India.
MS Ramaiah Medical College & Memorial Hospital, Bangalore, 560054, India.
Neuroimage. 2020 Jul 15;215:116826. doi: 10.1016/j.neuroimage.2020.116826. Epub 2020 Apr 7.
Gamma rhythms (~20-70 Hz) are abnormal in mental disorders such as autism and schizophrenia in humans, and Alzheimer's disease (AD) models in rodents. However, the effect of normal aging on these oscillations is unknown, especially for elderly subjects in whom AD is most prevalent. In a first large-scale (236 subjects; 104 females) electroencephalogram (EEG) study on gamma oscillations in elderly subjects (aged 50-88 years), we presented full-screen visual Cartesian gratings that induced two distinct gamma oscillations (slow: 20-34 Hz and fast: 36-66 Hz). Power decreased with age for gamma, but not alpha (8-12 Hz). Reduction was more salient for fast gamma than slow. Center frequency also decreased with age for both gamma rhythms. The results were independent of microsaccades, pupillary reactivity to stimulus, and variations in power spectral density with age. Steady-state visual evoked potentials (SSVEPs) at 32 Hz also reduced with age. These results are crucial for developing gamma/SSVEP-based biomarkers of cognitive decline in elderly.
伽马节律（~20-70 Hz）在精神障碍中异常，如人类的自闭症和精神分裂症，以及啮齿动物的阿尔茨海默病（AD）模型。然而，正常衰老对这些振荡的影响尚不清楚，特别是在 AD 最常见的老年人群中。在一项针对老年受试者（年龄 50-88 岁）伽马振荡的大规模（236 名受试者；104 名女性）脑电图（EEG）研究中，我们呈现了全屏幕视觉笛卡尔光栅，诱发了两种不同的伽马振荡（慢：20-34 Hz 和快：36-66 Hz）。伽马的功率随年龄而降低，但阿尔法（8-12 Hz）则不然。快伽马的减少比慢伽马更为显著。两种伽马节律的中心频率也随年龄而降低。这些结果与微眼跳、对刺激的瞳孔反应以及随年龄变化的功率谱密度无关。32 Hz 的稳态视觉诱发电位（SSVEP）也随年龄而降低。这些结果对于开发基于伽马/SSVEP 的老年认知衰退生物标志物至关重要。
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