Institute for Human Neuroscience, Boys Town National Research Hospital, Boys Town, NE, USA; College of Medicine, University of Nebraska Medical Center, Omaha, NE, USA.
Institute for Human Neuroscience, Boys Town National Research Hospital, Boys Town, NE, USA; College of Engineering, University of Nebraska - Lincoln, Lincoln, NE, USA.
Neuroimage. 2023 May 1;271:120020. doi: 10.1016/j.neuroimage.2023.120020. Epub 2023 Mar 12.
For decades, visual entrainment paradigms have been widely used to investigate basic visual processing in healthy individuals and those with neurological disorders. While healthy aging is known to be associated with alterations in visual processing, whether this extends to visual entrainment responses and the precise cortical regions involved is not fully understood. Such knowledge is imperative given the recent surge in interest surrounding the use of flicker stimulation and entrainment in the context of identifying and treating Alzheimer's disease (AD). In the current study, we examined visual entrainment in eighty healthy aging adults using magnetoencephalography (MEG) and a 15 Hz entrainment paradigm, while controlling for age-related cortical thinning. MEG data were imaged using a time-frequency resolved beamformer and peak voxel time series were extracted to quantify the oscillatory dynamics underlying the processing of the visual flicker stimuli. We found that, as age increased, the mean amplitude of entrainment responses decreased and the latency of these responses increased. However, there was no effect of age on the trial-to-trial consistency in phase (i.e., inter-trial phase locking) nor amplitude (i.e., coefficient of variation) of these visual responses. Importantly, we discovered that the relationship between age and response amplitude was fully mediated by the latency of visual processing. These results indicate that aging is associated with robust changes in the latency and amplitude of visual entrainment responses within regions surrounding the calcarine fissure, which should be considered in studies examining neurological disorders such as AD and other conditions associated with increased age.
几十年来，视觉诱发范式已被广泛用于研究健康个体和神经障碍患者的基本视觉处理。虽然众所周知，随着年龄的增长，视觉处理会发生变化，但这种变化是否会扩展到视觉诱发反应以及涉及的确切皮层区域，目前还不完全清楚。鉴于最近在使用闪烁刺激和诱发来识别和治疗阿尔茨海默病（AD）方面的兴趣激增，这种知识是至关重要的。在目前的研究中，我们使用脑磁图（MEG）和 15Hz 诱发范式检查了 80 名健康老年人的视觉诱发，同时控制了与年龄相关的皮层变薄。MEG 数据使用时频分辨波束形成器进行成像，并提取峰值体素时间序列，以量化视觉闪烁刺激处理的振荡动力学。我们发现，随着年龄的增长，诱发反应的平均幅度减小，这些反应的潜伏期增加。然而，年龄对这些视觉反应的相位（即，试验间相位锁定）和幅度（即，变异系数）的一致性没有影响。重要的是，我们发现年龄与反应幅度之间的关系完全由视觉处理的潜伏期介导。这些结果表明，衰老与围绕枕沟区域的视觉诱发反应的潜伏期和幅度的显著变化有关，在研究 AD 等与年龄增长相关的神经障碍以及其他与年龄相关的疾病时，应该考虑这些变化。
