França Arthur S C, do Nascimento George C, Lopes-dos-Santos Vítor, Muratori Larissa, Ribeiro Sidarta, Lobão-Soares Bruno, Tort Adriano B L
Brain Institute, Federal University of Rio Grande do Norte, Natal, RN 59056-450, Brazil; Edmond and Lily Safra International Institute of Neuroscience of Natal, Natal, Brazil.
Eur J Neurosci. 2014 Dec;40(11):3693-703. doi: 10.1111/ejn.12739. Epub 2014 Oct 7.
The oscillatory activity of hippocampal neuronal networks is believed to play a role in memory acquisition and consolidation. Particular focus has been given to characterising theta (4-12 Hz), gamma (40-100 Hz) and ripple (150-250 Hz) oscillations. Beyond these well-described network states, few studies have investigated hippocampal beta2 (23-30 Hz) activity in vivo and its link to behaviour. A previous sudy showed that the exploration of novel environments may lead to the appearance of beta2 oscillations in the mouse hippocampus. In the present study we characterised hippocampal beta2 oscillations in mice during an object recognition task. We found prominent bursts of beta2 oscillations in the beginning of novel exploration sessions (four new objects), which could be readily observed by spectral analysis and visual inspection of local field potentials. Beta2 modulated hippocampal but not neocortical neurons and its power decreased along the session. We also found increased beta2 power in the beginning of a second exploration session performed 24 h later in a slightly modified environment (two new, two familiar objects), but to a lesser extent than in the first session. However, the increase in beta2 power in the second exploration session became similar to the first session when we pharmacologically impaired object recognition in a new set of experiments performed 1 week later. Our results suggest that hippocampal beta2 activity is associated with a dynamic network state tuned for novelty detection and which may allow new learning to occur.
海马神经元网络的振荡活动被认为在记忆获取和巩固中发挥作用。人们特别关注对θ波（4 - 12赫兹）、γ波（40 - 100赫兹）和涟漪波（150 - 250赫兹）振荡的特征描述。除了这些已被充分描述的网络状态外，很少有研究在体内研究海马β2波（23 - 30赫兹）的活动及其与行为的联系。先前的一项研究表明，对新环境的探索可能会导致小鼠海马中出现β2波振荡。在本研究中，我们在物体识别任务期间对小鼠海马β2波振荡进行了特征描述。我们发现在新探索阶段开始时（四个新物体）有明显的β2波振荡爆发，通过频谱分析和局部场电位的视觉检查很容易观察到。β2波调节海马神经元而非新皮层神经元，并且其功率在整个阶段逐渐降低。我们还发现在24小时后在稍微改变的环境中进行的第二次探索阶段开始时（两个新物体，两个熟悉物体）β2波功率增加，但程度小于第一次探索阶段。然而，当我们在1周后进行的一组新实验中通过药理学方法损害物体识别时，第二次探索阶段β2波功率的增加与第一次探索阶段变得相似。我们的结果表明，海马β2波活动与一种为新奇检测而调整的动态网络状态相关，并且可能允许新的学习发生。
