Stellate cells (SCs) of the medial entorhinal cortex (MEC) are rich in hyperpolarization‐activated cyclic nucleotide–gated (HCN) channels, which are known to effectively shape their activity patterns. The explanatory mechanisms, however, have remained elusive. One important but previously unassessed possibility is that HCN channels control the gain of synaptic inputs to these cells. Here, we test this possibility in rat brain slices, while subjecting SCs to a stochastic synaptic bombardment using the dynamic clamp. We show that in the presence of synaptic noise, HCN channels mainly exert their influence by increasing the relative signal gain in the theta frequency through the theta modulation of stochastic synaptic inputs. This subthreshold synaptic modulation then translates into a spiking resonance, which steepens with excitation in the presence of HCN channels. We present here a systematic assessment of synaptic theta modulation and trace its implications to the suprathreshold control of firing rate motifs. Such analysis was yet lacking in the SC literature. Furthermore, we assess the impact of noise statistics on this gain modulation and indicate possible mechanisms for the emergence of membrane theta oscillations and synaptic ramps, as observed in vivo. We support the data with a computational model that further unveils a competing role of inhibition, suggesting important implications for MEC computations.

中文翻译：

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内侧内嗅皮层星状细胞中的θ共振和突触调制尺度活动模式

内侧内嗅皮层 (MEC) 的星状细胞 (SC) 富含超极化激活的环核苷酸门控 (HCN) 通道，已知这些通道可有效塑造其活动模式。然而，解释机制仍然难以捉摸。一种重要但以前未评估的可能性是 HCN 通道控制这些细胞的突触输入的增益。在这里，我们在大鼠脑切片中测试了这种可能性，同时使用动态钳对 SCs 进行随机突触轰击。我们表明，在存在突触噪声的情况下，HCN 通道主要通过随机突触输入的 theta 调制增加 theta 频率的相对信号增益来发挥其影响。这种亚阈值突触调制然后转化为尖峰共振，在 HCN 通道存在的情况下，它会随着激发而变得陡峭。我们在这里介绍了对突触 theta 调制的系统评估，并将其影响追溯到激发率图案的超阈值控制。SC 文献中还缺乏这种分析。此外，我们评估了噪声统计对这种增益调制的影响，并指出了在体内观察到的膜θ振荡和突触斜坡出现的可能机制。我们使用计算模型支持数据，该模型进一步揭示了抑制的竞争作用，表明对 MEC 计算具有重要意义。我们评估了噪声统计对这种增益调制的影响，并指出了在体内观察到的膜θ振荡和突触斜坡出现的可能机制。我们使用计算模型支持数据，该模型进一步揭示了抑制的竞争作用，表明对 MEC 计算具有重要意义。我们评估了噪声统计对这种增益调制的影响，并指出了在体内观察到的膜θ振荡和突触斜坡出现的可能机制。我们使用计算模型支持数据，该模型进一步揭示了抑制的竞争作用，表明对 MEC 计算具有重要意义。