Montreal Neurological Institute, McGill University, 845 Sherbrooke St W, Montreal, QC, H3A 0G4, Canada.
Department of Neurological Sciences, University of Nebraska Medical Center, Omaha, NE, USA.
Alzheimers Res Ther. 2021 Aug 17;13(1):139. doi: 10.1186/s13195-021-00881-w.
Entrainment of neural oscillations in occipital cortices by external rhythmic visual stimuli has been proposed as a novel therapy for patients with Alzheimer's disease (AD). Despite this increased interest in visual neural oscillations in AD, little is known regarding their role in AD-related cognitive impairment and in particular during visuospatial processing.
We used source-imaged magnetoencephalography (MEG) and an established visuospatial processing task to elicit multi-spectral neuronal responses in 35 biomarker-confirmed patients on the AD spectrum and 20 biomarker-negative older adults. Neuronal oscillatory responses were imaged to the level of the cortex, and group classifications and neurocognitive relationships were modeled using logistic and linear regression, respectively.
Visuospatial neuronal oscillations in the theta, alpha, and gamma ranges significantly predicted the classification of patients on the AD spectrum. Importantly, the direction of these effects differed by response frequency, such that patients on the AD spectrum exhibited weaker alpha-frequency responses in lateral occipital regions, and stronger gamma-frequency responses in the primary visual cortex, as compared to biomarker-negative older adults. In addition, alpha and gamma, but not theta, oscillations robustly predicted cognitive status (i.e., MoCA and MMSE scores), such that patients with neural responses that deviated more from those of healthy older adults exhibited poorer cognitive performance.
We find that the multi-spectral neural dynamics supporting visuospatial processing differentiate patients on the AD spectrum from cognitively normal, biomarker-negative older adults. Oscillations in the alpha and gamma bands also relate to cognitive status in ways that are informative for emerging clinical interventions.
通过外部节律性视觉刺激诱发枕叶皮质中的神经振荡，已被提议作为治疗阿尔茨海默病（AD）患者的一种新方法。尽管人们对 AD 中的视觉神经振荡越来越感兴趣，但对于它们在 AD 相关认知障碍中的作用，尤其是在视觉空间处理中的作用，人们知之甚少。
我们使用源成像脑磁图（MEG）和已建立的视觉空间处理任务，在 AD 谱中的 35 名生物标志物确诊患者和 20 名生物标志物阴性的老年成年人中诱发出多谱神经元反应。对神经元振荡反应进行皮层水平的成像，并分别使用逻辑回归和线性回归对群体分类和神经认知关系进行建模。
θ、α 和γ频段的视觉空间神经元振荡显著预测了 AD 谱患者的分类。重要的是，这些效应的方向因反应频率而异，与生物标志物阴性的老年成年人相比，AD 谱患者在外侧枕叶区域表现出较弱的α 频率反应，而在初级视觉皮层中表现出较强的γ 频率反应。此外，α 和γ 但不是θ 振荡强烈预测认知状态（即 MoCA 和 MMSE 评分），因此，神经反应与健康老年成年人的反应偏差越大的患者表现出较差的认知表现。
我们发现，支持视觉空间处理的多谱神经动力学可将 AD 谱患者与认知正常、生物标志物阴性的老年成年人区分开来。α 和γ 波段的振荡也以对新兴临床干预有信息的方式与认知状态相关。
