Brain states modulate the membrane potential dynamics of neurons, influencing the functional repertoire of the network. Pyramidal cells (PCs) in the hippocampal CA3 are necessary for rapid memory encoding, which preferentially occurs during exploratory behavior in the high-arousal theta state. However, the relationship between the membrane potential dynamics of CA3 PCs and theta has not been explored. Here we characterize the changes in the membrane potential of PCs in relation to theta using electrophysiological recordings in awake mice. During theta, most PCs behave in a stereotypical manner, consistently hyperpolarizing time-locked to the duration of theta. Additionally, PCs display lower membrane potential variance and a reduced firing rate. In contrast, during large irregular activity, PCs show heterogeneous changes in membrane potential. This suggests coordinated hyperpolarization of PCs during theta, possibly caused by increased inhibition. This could lead to a higher signal-to-noise ratio in the small population of PCs active during theta, as observed in ensemble recordings.

脑状态调节神经元的膜电位动态，影响网络的功能库。海马CA3中的金字塔形细胞（PC）是快速记忆编码所必需的，快速记忆编码优先发生在高唤醒theta状态下的探索行为期间。但是，尚未探讨CA3 PCs的膜电位动力学与theta之间的关系。在这里，我们使用清醒小鼠的电生理记录来表征PC的膜电位相对于theta的变化。在θ期间，大多数PC都以定型方式工作，始终超极化时间锁定到θ的持续时间。另外，PC显示出较低的膜电位变化和降低的发射速率。相反，在大量的不规则活动中，PCs的膜电位显示出不同的变化。这表明在θ期间PC的协同超极化，可能是由于抑制增加所致。如在合奏录音中所观察到的，这可能导致在theta期间处于活动状态的少量PC产生更高的信噪比。