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 Jun;16(3):643-665. doi: 10.1007/s11571-021-09728-4. Epub 2021 Oct 23.
We investigate population and individual firing behaviors in sparsely synchronized rhythms (SSRs) in a spiking neural network of the hippocampal dentate gyrus (DG). The main encoding granule cells (GCs) are grouped into lamellar clusters. In each GC cluster, there is one inhibitory (I) basket cell (BC) along with excitatory (E) GCs, and they form the E-I loop. Winner-take-all competition, leading to sparse activation of the GCs, occurs in each GC cluster. Such sparsity has been thought to enhance pattern separation performed in the DG. During the winner-take-all competition, SSRs are found to appear in each population of the GCs and the BCs through interaction of excitation of the GCs with inhibition of the BCs. Sparsely synchronized spiking stripes appear successively with the population frequency Hz) in the raster plots of spikes. We also note that excitatory hilar mossy cells (MCs) control the firing activity of the GC-BC loop by providing excitation to both the GCs and the BCs. SSR also appears in the population of MCs via interaction with the GCs (i.e., GC-MC loop). Population behaviors in the SSRs are quantitatively characterized in terms of the synchronization measures. In addition, we investigate individual firing activity of GCs, BCs, and MCs in the SSRs. Individual GCs exhibit random spike skipping, leading to a multi-peaked inter-spike-interval histogram, which is well characterized in terms of the random phase-locking degree. In this case, population-averaged mean-firing-rate (MFR) is less than the population frequency . On the other hand, both BCs and MCs show "intrastripe" burstings within stripes, together with random spike skipping. Thus, the population-averaged MFR ( MC and BC) is larger than , in contrast to the case of the GCs. MC loss may occur during epileptogenesis. With decreasing the fraction of the MCs, changes in the population and individual firings in the SSRs are also studied. Finally, quantitative association between the population/individual firing behaviors in the SSRs and the winner-take-all competition is discussed.
我们研究了海马齿状回（DG）的脉冲神经网络中稀疏同步节律（SSR）下的群体和个体放电行为。主要的编码颗粒细胞（GCs）被分组为层状簇。在每个GC簇中，有一个抑制性（I）篮状细胞（BC）以及兴奋性（E）GCs，它们形成E-I回路。在每个GC簇中发生胜者全得竞争，导致GCs的稀疏激活。这种稀疏性被认为可以增强DG中执行的模式分离。在胜者全得竞争期间，通过GCs的兴奋与BCs的抑制之间的相互作用，发现在GCs和BCs的每个群体中都会出现SSR。在脉冲的光栅图中，稀疏同步的脉冲条纹以群体频率（Hz）相继出现。我们还注意到，兴奋性的海马苔藓细胞（MCs）通过向GCs和BCs提供兴奋来控制GC-BC回路的放电活动。SSR也通过与GCs的相互作用（即GC-MC回路）出现在MCs群体中。SSR中的群体行为通过同步测量进行定量表征。此外，我们研究了SSR中GCs、BCs和MCs的个体放电活动。单个GCs表现出随机的脉冲跳过，导致峰间间隔直方图呈多峰状，这可以通过随机锁相程度很好地表征。在这种情况下，群体平均平均放电率（MFR）小于群体频率。另一方面，BCs和MCs在条纹内都表现出“条纹内”爆发，同时伴有随机的脉冲跳过。因此，与GCs的情况相反，群体平均MFR（对于MCs和BCs）大于。在癫痫发生过程中可能会出现MCs丢失。随着MCs比例的降低，还研究了SSR中群体和个体放电的变化。最后，讨论了SSR中群体/个体放电行为与胜者全得竞争之间的定量关联。
