Kim Sang-Yoon, Lim Woochang
Institute for Computational Neuroscience and Department of Science Education, Daegu National University of Education, Daegu, 42411 Korea.
Cogn Neurodyn. 2022 Dec;16(6):1427-1447. doi: 10.1007/s11571-022-09797-z. Epub 2022 Mar 24.
We study the disynaptic effect of the hilar cells on pattern separation in a spiking neural network of the hippocampal dentate gyrus (DG). The principal granule cells (GCs) in the DG perform pattern separation, transforming similar input patterns into less-similar output patterns. In our DG network, the hilus consists of excitatory mossy cells (MCs) and inhibitory HIPP (hilar perforant path-associated) cells. Here, we consider the disynaptic effects of the MCs and the HIPP cells on the GCs, mediated by the inhibitory basket cells (BCs) in the granular layer; MC BC GC and HIPP BC GC. The MCs provide disynaptic inhibitory input (mediated by the intermediate BCs) to the GCs, which decreases the firing activity of the GCs. On the other hand, the HIPP cells disinhibit the intermediate BCs, which leads to increasing the firing activity of the GCs. In this way, the disynaptic effects of the MCs and the HIPP cells are opposite. We investigate change in the pattern separation efficacy by varying the synaptic strength [from the pre-synaptic X (= MC or HIPP) to the post-synaptic BC]. Thus, sparsity for the firing activity of the GCs is found to improve the efficacy of pattern separation, and hence the disynaptic effects of the MCs and the HIPP cells on the pattern separation become opposite ones. In the combined case when simultaneously changing both and , as a result of balance between the two competing disynaptic effects of the MCs and the HIPP cells, the efficacy of pattern separation is found to become the highest at their original default values where the activation degree of the GCs is the lowest. We also note that, while the GCs perform pattern separation, sparsely synchronized rhythm is found to appear in the population of the GCs. Hence, we examine quantitative association between population and individual firing behaviors in the sparsely synchronized rhythm and pattern separation. They are found to be strongly correlated. Consequently, the better the population and individual firing behaviors in the sparsely synchronized rhythm are, the more pattern separation efficacy becomes enhanced.
我们研究了海马齿状回（DG）的脉冲神经网络中 hilar 细胞对模式分离的双突触效应。DG 中的主要颗粒细胞（GCs）执行模式分离，将相似的输入模式转换为不太相似的输出模式。在我们的 DG 网络中，hilus 由兴奋性苔藓细胞（MCs）和抑制性 HIPP（hilus 穿通路径相关）细胞组成。在这里，我们考虑 MCs 和 HIPP 细胞通过颗粒层中的抑制性篮状细胞（BCs）对 GCs 的双突触效应；即 MC→BC→GC 和 HIPP→BC→GC。MCs 向 GCs 提供双突触抑制性输入（由中间 BCs 介导），这会降低 GCs 的放电活动。另一方面，HIPP 细胞解除对中间 BCs 的抑制，从而导致 GCs 的放电活动增加。这样，MCs 和 HIPP 细胞的双突触效应是相反的。我们通过改变突触强度[从突触前的 X（=MC 或 HIPP）到突触后的 BC]来研究模式分离效能的变化。因此，发现 GCs 放电活动的稀疏性提高了模式分离的效能，因此 MCs 和 HIPP 细胞对模式分离的双突触效应也变得相反。在同时改变两者的组合情况下，由于 MCs 和 HIPP 细胞的两种相互竞争的双突触效应之间的平衡，发现模式分离效能在 GCs 激活程度最低的原始默认值时最高。我们还注意到，虽然 GCs 执行模式分离，但在 GCs 群体中发现出现了稀疏同步节律。因此，我们研究了稀疏同步节律和模式分离中群体与个体放电行为之间的定量关联。发现它们密切相关。因此，稀疏同步节律中的群体和个体放电行为越好，模式分离效能就越强。
