Nokia Miriam S, Mikkonen Jarno E, Penttonen Markku, Wikgren Jan
Department of Psychology, University of Jyväskylä Jyväskylä, Finland.
Front Behav Neurosci. 2012 Dec 4;6:84. doi: 10.3389/fnbeh.2012.00084. eCollection 2012.
Oscillations in hippocampal local-field potentials (LFPs) reflect the crucial involvement of the hippocampus in memory trace formation: theta (4-8 Hz) oscillations and ripples (~200 Hz) occurring during sharp waves are thought to mediate encoding and consolidation, respectively. During sharp wave-ripple complexes (SPW-Rs), hippocampal cell firing closely follows the pattern that took place during the initial experience, most likely reflecting replay of that event. Disrupting hippocampal ripples using electrical stimulation either during training in awake animals or during sleep after training retards spatial learning. Here, adult rabbits were trained in trace eyeblink conditioning, a hippocampus-dependent associative learning task. A bright light was presented to the animals during the inter-trial interval (ITI), when awake, either during SPW-Rs or irrespective of their neural state. Learning was particularly poor when the light was presented following SPW-Rs. While the light did not disrupt the ripple itself, it elicited a theta-band oscillation, a state that does not usually coincide with SPW-Rs. Thus, it seems that consolidation depends on neuronal activity within and beyond the hippocampus taking place immediately after, but by no means limited to, hippocampal SPW-Rs.
海马局部场电位（LFP）的振荡反映了海马在记忆痕迹形成中的关键作用：尖锐波期间出现的θ波（4 - 8赫兹）振荡和涟漪（约200赫兹）分别被认为介导编码和巩固。在尖锐波 - 涟漪复合体（SPW - Rs）期间，海马细胞放电紧密跟随初始经历期间发生的模式，很可能反映了该事件的重演。在清醒动物训练期间或训练后的睡眠期间使用电刺激破坏海马涟漪会阻碍空间学习。在此，成年兔子接受痕迹眨眼条件反射训练，这是一项依赖海马的联想学习任务。当动物清醒时，在试验间隔（ITI）期间，无论是在SPW - Rs期间还是与其神经状态无关的情况下，都会向它们呈现明亮的光线。当在SPW - Rs之后呈现光线时，学习效果特别差。虽然光线并未破坏涟漪本身，但它引发了θ波段振荡，这种状态通常与SPW - Rs不一致。因此，似乎巩固依赖于海马SPW - Rs之后紧接着发生的、但绝不仅限于海马内部和外部的神经元活动。
