Başar Erol, Emek-Savaş Derya Durusu, Güntekin Bahar, Yener Görsev G
Brain Dynamics, Cognition and Complex Systems Research Center, Istanbul Kultur University, Istanbul 34156, Turkey.
Brain Dynamics, Cognition and Complex Systems Research Center, Istanbul Kultur University, Istanbul 34156, Turkey; Department of Psychology, Dokuz Eylül University, Izmir 35160, Turkey; Department of Neurosciences, Dokuz Eylül University, Izmir 35340, Turkey.
Neuroimage Clin. 2016 Jan 20;11:106-115. doi: 10.1016/j.nicl.2016.01.015. eCollection 2016.
Event-related oscillations (EROs) reflect cognitive brain dynamics, while sensory-evoked oscillations (SEOs) reflect sensory activities. Previous reports from our lab have shown that those with Alzheimer's disease (AD) or mild cognitive impairment (MCI) have decreased activity and/or coherence in delta, theta, alpha and beta cognitive responses. In the current study, we investigated gamma responses in visual SEO and ERO in 15 patients with AD and in 15 age-, gender- and education-matched healthy controls. The following parameters were analyzed over the parietal-occipital regions in both groups: (i) latency of the maximum gamma response over a 0-800 ms time window; (ii) the maximum peak-to-peak amplitudes for each participant's averaged SEO and ERO gamma responses in 3 frequency ranges (25-30, 30-35, 40-48 Hz); and (iii) the maximum peak-to-peak amplitudes for each participant's averaged SEO and ERO gamma responses over a 0-800 ms time block containing four divided time windows (0-200, 200-400, 400-600, and 600-800 ms). There were main group effects in terms of both latency and peak-to-peak amplitudes of gamma ERO. However, peak-to-peak gamma ERO amplitude differences became noticeable only when the time block was divided into four time windows. SEO amplitudes in the 25-30 Hz frequency range of the 0-200 ms time window over the left hemisphere were greater in the healthy controls than in those with AD. Gamma target ERO latency was delayed up to 138 ms in AD patients when compared to healthy controls. This finding may be an effect of lagged neural signaling in cognitive circuits, which is reflected by the delayed gamma responses in those with AD. Based on the results of this study, we propose that gamma responses should be examined in a more detailed fashion using multiple frequency and time windows.
事件相关振荡（EROs）反映认知脑动力学，而感觉诱发振荡（SEOs）反映感觉活动。我们实验室之前的报告表明，患有阿尔茨海默病（AD）或轻度认知障碍（MCI）的人在δ、θ、α和β认知反应中的活动和/或连贯性降低。在本研究中，我们调查了15名AD患者以及15名年龄、性别和教育程度匹配的健康对照者在视觉SEOs和EROs中的γ反应。在两组的顶枕区域分析了以下参数：（i）在0 - 800毫秒时间窗口内最大γ反应的潜伏期；（ii）每个参与者在3个频率范围（25 - 30、30 - 35、40 - 48赫兹）的平均SEOs和EROsγ反应的最大峰峰值幅度；（iii）每个参与者在包含四个划分时间窗口（0 - 200、200 - 400、400 - 600和600 - 800毫秒）的0 - 800毫秒时间块内的平均SEOs和EROsγ反应的最大峰峰值幅度。在γ ERO的潜伏期和峰峰值幅度方面存在主要的组间效应。然而，只有当时间块被划分为四个时间窗口时，峰峰值γ ERO幅度差异才变得明显。在左半球0 - 200毫秒时间窗口的25 - 30赫兹频率范围内，健康对照者的SEOs幅度大于AD患者。与健康对照者相比，AD患者的γ目标ERO潜伏期延迟长达138毫秒。这一发现可能是认知回路中神经信号滞后的结果，这在AD患者延迟的γ反应中得到体现。基于本研究结果，我们建议应使用多个频率和时间窗口以更详细的方式检查γ反应。
