Shaw Fu-Zen, Chew Jia-Her
Institute of Neuroscience, Tzu Chi University, No. 701, Chung Yang Road, Sec. 3, Hualien 970, Taiwan.
Brain Res. 2003 Sep 5;983(1-2):152-61. doi: 10.1016/s0006-8993(03)03048-8.
Somatic evoked potentials (SEPs) from three brain sites elicited by electrical stimulation in 10 rats were recorded throughout wake-sleep states with intrinsic changes in temporal architectures under different vigilance states. Based on the patterns of spontaneous brain and muscle activities, three characteristic vigilance states could be classified: awake, slow-wave sleep (SWS), and paradoxical sleep (PS). Spontaneous gamma activities prominently appeared under awake and PS states, but less under SWS. SEP was filtered out via a zero-phase highpass filter (20 Hz) to extract the gamma activity of the SEP (gammaSEP). Gamma oscillations of SEPs were clearly observed and were reset by extrinsic electrical stimulation under awake and PS, but not under SWS state. Dynamic changes of gammaSEPs during wake-sleep states were also confirmed by multiple single-trial spectral analyses. Moreover, gamma oscillations were initiated at the parietal site, and the speed of its propagation in both frontal and occipital directions was significantly different. In addition, a clear two-component architecture of SEPs was observed under awake and PS states, and the gamma rhythmic activity was associated with the second component. Because gamma oscillations are related to feature binding in the waking state, evoked gammaSEPs in PS may be related to sensory integration analogous to the awake ones. By contrast, a long-lasting biphasic component of SEPs, which might be associated with augmenting response, was observed during SWS. Based on these results, the sleeping brain continuously monitors and selectively processes incoming flow. Our results also strongly support a two-stage information processing taking place in the cortex during sleep.
在10只大鼠中，通过电刺激诱发了来自三个脑区的体感诱发电位（SEP），在不同警觉状态下，随着时间结构的内在变化，在整个清醒-睡眠状态下进行记录。根据自发脑电和肌肉活动的模式，可以将三种特征性警觉状态分类：清醒、慢波睡眠（SWS）和异相睡眠（PS）。自发伽马活动在清醒和PS状态下显著出现，但在SWS状态下较少。通过零相位高通滤波器（20Hz）滤除SEP，以提取SEP的伽马活动（gammaSEP）。在清醒和PS状态下，清楚地观察到SEP的伽马振荡，并被外部电刺激重置，但在SWS状态下则不然。多次单次试验频谱分析也证实了清醒-睡眠状态下gammaSEP的动态变化。此外，伽马振荡在顶叶部位起始，其在额叶和枕叶方向的传播速度显著不同。另外，在清醒和PS状态下观察到SEP清晰的双成分结构，伽马节律活动与第二个成分相关。由于伽马振荡在清醒状态下与特征绑定有关，PS状态下诱发的gammaSEP可能与类似于清醒状态下的感觉整合有关。相比之下，在SWS期间观察到SEP的一个持久双相成分，其可能与增强反应有关。基于这些结果，睡眠中的大脑持续监测并选择性地处理传入信息流。我们的结果也有力地支持了睡眠期间在皮层中发生的两阶段信息处理。
