Department of Neurobiology, Weizmann Institute of Science, Rehovot, 76100, Israel.
HHMI Janelia Research Campus, Ashburn, Virginia, 20147, USA.
Hippocampus. 2017 Sep;27(9):959-970. doi: 10.1002/hipo.22743. Epub 2017 Jun 14.
Hippocampal place cells represent different environments with distinct neural activity patterns. Following an abrupt switch between two familiar configurations of visual cues defining two environments, the hippocampal neural activity pattern switches almost immediately to the corresponding representation. Surprisingly, during a transient period following the switch to the new environment, occasional fast transitions between the two activity patterns (flickering) were observed (Jezek, Henriksen, Treves, Moser, & Moser, ). Here we show that an attractor neural network model of place cells with connections endowed with short-term synaptic plasticity can account for this phenomenon. A memory trace of the recent history of network activity is maintained in the state of the synapses, allowing the network to temporarily reactivate the representation of the previous environment in the absence of the corresponding sensory cues. The model predicts that the number of flickering events depends on the amplitude of the ongoing theta rhythm and the distance between the current position of the animal and its position at the time of cue switching. We test these predictions with new analysis of experimental data. These results suggest a potential role of short-term synaptic plasticity in recruiting the activity of different cell assemblies and in shaping hippocampal activity of behaving animals.
海马体位置细胞以不同的神经活动模式来代表不同的环境。在两个熟悉的视觉提示配置之间突然切换以定义两个环境之后，海马体的神经活动模式几乎立即切换到相应的表示。令人惊讶的是，在切换到新环境后的短暂期间内，观察到两个活动模式之间偶尔发生快速转换（闪烁）（Jezek、Henriksen、Treves、Moser 和 Moser，）。在这里，我们展示了具有短期突触可塑性的连接的位置细胞吸引子神经网络模型可以解释这一现象。网络活动的最近历史的记忆痕迹保存在突触状态中，允许网络在没有相应感觉提示的情况下暂时重新激活先前环境的表示。该模型预测，闪烁事件的数量取决于当前theta 节律的幅度和动物当前位置与其在提示切换时的位置之间的距离。我们使用新的实验数据分析来检验这些预测。这些结果表明短期突触可塑性在招募不同细胞集合的活动以及塑造行为动物的海马体活动方面可能发挥作用。
