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Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA.
Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA.
Neuron. 2017 Oct 11;96(2):490-504.e5. doi: 10.1016/j.neuron.2017.09.029.
Hippocampal place cell ensembles form a cognitive map of space during exposure to novel environments. However, surprisingly little evidence exists to support the idea that synaptic plasticity in place cells is involved in forming new place fields. Here we used high-resolution functional imaging to determine the signaling patterns in CA1 soma, dendrites, and axons associated with place field formation when mice are exposed to novel virtual environments. We found that putative local dendritic spikes often occur prior to somatic place field firing. Subsequently, the first occurrence of somatic place field firing was associated with widespread regenerative dendritic events, which decreased in prevalence with increased novel environment experience. This transient increase in regenerative events was likely facilitated by a reduction in dendritic inhibition. Since regenerative dendritic events can provide the depolarization necessary for Hebbian potentiation, these results suggest that activity-dependent synaptic plasticity underlies the formation of many CA1 place fields.
在接触新环境期间，海马体位置细胞集合形成空间认知地图。然而，令人惊讶的是，几乎没有证据支持位置细胞中的突触可塑性参与形成新位置野这一观点。在这里，我们使用高分辨率功能成像来确定小鼠暴露于新虚拟环境时，与位置野形成相关的CA1体细胞、树突和轴突中的信号模式。我们发现，假定的局部树突棘突通常在体细胞位置野放电之前出现。随后，体细胞位置野放电的首次出现与广泛的再生树突事件相关，随着对新环境体验的增加，这种事件的发生率降低。再生事件的这种短暂增加可能是由树突抑制的减少所促进的。由于再生树突事件可以提供赫布增强所需的去极化，这些结果表明，活动依赖的突触可塑性是许多CA1位置野形成的基础。
