Department of Psychology, University of Connecticut Storrs, Storrs, CT, USA.
Prog Brain Res. 2011;193:181-99. doi: 10.1016/B978-0-444-53839-0.00012-0.
Large amplitude slow waves are characteristic for the summary brain activity, recorded as electroencephalogram (EEG) or local field potentials (LFP), during deep stages of sleep and some types of anesthesia. Slow rhythm of the synchronized EEG reflects an alternation of active (depolarized, UP) and silent (hyperpolarized, DOWN) states of neocortical neurons. In neurons, involvement in the generalized slow oscillation results in a long-range synchronization of changes of their membrane potential as well as their firing. Here, we aimed at intracellular analysis of details of this synchronization. We asked which components of neuronal activity exhibit long-range correlations during the synchronized EEG? To answer this question, we made simultaneous intracellular recordings from two to four neocortical neurons in cat neocortex. We studied how correlated is the occurrence of active and silent states, and how correlated are fluctuations of the membrane potential in pairs of neurons located close one to the other or separated by up to 13 mm. We show that strong long-range correlation of the membrane potential was observed only (i) during the slow oscillation but not during periods without the oscillation, (ii) during periods which included transitions between the states but not during within-the-state periods, and (iii) for the low-frequency (< 5 Hz) components of membrane potential fluctuations but not for the higher-frequency components (> 10 Hz). In contrast to the neurons located several millimeters one from the other, membrane potential fluctuations in neighboring neurons remain strongly correlated during periods without slow oscillation. We conclude that membrane potential correlation in distant neurons is brought about by synchronous transitions between the states, while activity within the states is largely uncorrelated. The lack of the generalized fine-scale synchronization of membrane potential changes in neurons during the active states of slow oscillation may allow individual neurons to selectively engage in short living episodes of correlated activity-a process that may be similar to dynamical formation of neuronal ensembles during activated brain states.
大振幅慢波是深度睡眠和某些类型麻醉期间记录的脑电图 (EEG) 或局部场电位 (LFP) 的特征，代表大脑的综合活动。同步 EEG 的缓慢节律反映了新皮层神经元活跃（去极化，UP）和沉默（超极化，DOWN）状态的交替。在神经元中，参与广义慢波振荡导致其膜电位变化以及其放电的长程同步。在这里，我们旨在对内电路分析这种同步的细节。我们问在同步 EEG 期间，神经元活动的哪些成分表现出长程相关性？为了回答这个问题，我们在猫新皮层的两个到四个新皮层神经元中同时进行了细胞内记录。我们研究了活跃和沉默状态的发生如何相关，以及彼此靠近或相隔 13 毫米的神经元对之间的膜电位波动如何相关。我们发现，只有在（i）慢波振荡期间而不是在没有振荡的期间，（ii）包括状态之间的转换的期间而不是在状态内期间，以及（iii）膜电位波动的低频（<5 Hz）分量而不是高频（>10 Hz）分量，才观察到膜电位的强长程相关性。与相隔几毫米的神经元相比，在没有慢波振荡的期间，相邻神经元的膜电位波动仍然保持强烈相关性。我们得出结论，远隔神经元的膜电位相关性是由状态之间的同步转换引起的，而状态内的活动则主要不相关。在慢波振荡的活跃状态期间，神经元中膜电位变化的广义精细同步缺失可能允许单个神经元选择性地参与相关活动的短暂生存事件——这一过程可能类似于激活大脑状态期间神经元集合的动态形成。
