Trinity College Institute of Neuroscience.
School of Psychology.
eNeuro. 2019 Mar 22;6(2). doi: 10.1523/ENEURO.0423-17.2019. eCollection 2019 Mar-Apr.
Hippocampal place cells are known to have a key role in encoding spatial information. Aversive stimuli, such as predator odor, evoke place field remapping and a change in preferred firing locations. However, it remains unclear how place cells use positive or negative experiences to remap. We investigated whether CA1 place cells, recorded from behaving rats, remap randomly or whether their reconfiguration depends on the perceived location of the aversive stimulus. Exposure to trimethylthiazoline (TMT; an innately aversive odor), increased the amplitude of hippocampal β oscillations in the two arms of the maze in which TMT exposure occurred. We found that a population of place cells with fields located outside the TMT arms increased their activity (extrafield spiking) in the TMT arms during the aversive episodes. Moreover, in the subsequent post-TMT recording, these cells exhibited a significant shift in their center of mass (COM) towards the TMT arms. The induction of extrafield plasticity was mediated by the basolateral amygdala complex (BLA). Photostimulation of the BLA triggered aversive behavior, synchronized hippocampal local field oscillations, and increased the extrafield spiking of the hippocampal place cells for the first 100 ms after light delivery. Optogenetic BLA activation triggered an increase in extrafield spiking activity that was correlated with the degree of place field plasticity. Furthermore, BLA-mediated increase of the extrafield activity predicts the degree of subsequent field plasticity. Our findings demonstrate that that the remapping of hippocampal place cells during aversive episodes is not random but it depends on the location of the aversive stimulus.
海马体位置细胞在编码空间信息方面起着关键作用。厌恶刺激，如捕食者的气味，会引起位置场重映射和首选发射位置的变化。然而，目前尚不清楚位置细胞如何利用正、负经验来进行重映射。我们研究了在行为大鼠中记录的 CA1 位置细胞是随机重映射还是其重新配置取决于厌恶刺激的感知位置。暴露于三甲噻吨（TMT；一种天生厌恶的气味）会增加迷宫中 TMT 暴露的两个臂中海马β 振荡的幅度。我们发现，位于 TMT 臂外的位置细胞群体，在厌恶事件期间，其活动（场外尖峰）在 TMT 臂中增加。此外，在随后的 TMT 后记录中，这些细胞的质心（COM）明显向 TMT 臂移动。场外可塑性的诱导是由基底外侧杏仁核复合体（BLA）介导的。BLA 的光刺激引发厌恶行为，同步海马局部场振荡，并在光传递后 100 毫秒内增加海马位置细胞的场外尖峰。光遗传 BLA 激活引发的场外尖峰活动增加与位置场可塑性的程度相关。此外，BLA 介导的场外活动增加可预测随后的场可塑性程度。我们的发现表明，在厌恶事件期间，海马体位置细胞的重映射不是随机的，而是取决于厌恶刺激的位置。
