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. Author manuscript; available in PMC: 2022 May 27.
Published in final edited form as: Cell Rep. 2021 May 11;35(6):109106. doi: 10.1016/j.celrep.2021.109106

Figure 7. A network model with Chn-driven circuit modules reproduces sharp waves.

Figure 7.

(A) Top, network model constructed with 20,572 neurons occupying a volume of 1,400 × 1,400 × 400 μm comprising the following three cell types (proportions): PNs (80%), basket INs (18%), and Chns (2%). Bottom, schematic of circuit organization in a single module consisting of a Chn (cyan) connected to a PN (s) (red) that then projects to an IN (s) (gray) and other Chn (s); +/− indicate excitatory/inhibitory connection. Adjacent modules recruited through Chns.

(B) A single AP discharge in a Chn in the network model evoked a time-locked feedback burst. Gray traces are from individual Chns (n = 16) overlaid with the mean (cyan). Top, current-clamp traces show that a single AP in a Chn-evoked feedback EPSP that triggered time-locked burst of APs; bottom, voltage-clamp traces show a single AP (unclamped action current) in a Chn followed by time-locked burst of feedback EPSCs.

(C) A Chn-evoked feedback burst occurred with a population burst and transition in the LFP in the network model. Raster plot shows the timing of spike discharge of Chns (cyan), PNs (red), and INs (gray) during a Chn (cyan)-evoked population burst against distance from the initiator (upward arrow at time zero). The wide-band LFP at the center of the model during the population burst is overlaid in black. Note that the initiating Chn (at time zero) drives only two PNs (red) before the activity propagates through the network.

(D) Spectral analysis of the LFP at the center of the network model from 16 trials of evoked population burst from different Chns shows enhanced power in the SW and ripple frequency bands.

(E) Chns in the model initiated an IPSC burst in PNs and an EPSC burst in INs with intrinsic frequency of ~250 Hz. Left, top to bottom traces show a superimposed feedback EPSC burst (gray) from 16 Chns overlaid with mean (cyan); simultaneously recorded synaptic currents in PNs (middle) show a burst of IPSCs (gray, mean in red) and in INs (bottom) show a burst of EPSCs (gray, mean in red). Right, (top to bottom) spectral analysis of synaptic current bursts in Chns, PNs, and INs shows enhanced power at ~250 Hz. Mean highlighted and overlaid on individual episodes (gray).

(F) Proportion of cells recruited by the initiating Chn to discharge AP(s) in each cycle.

(G) Top traces show the LFP from 16 trials with each trial initiated by different Chns and band-pass filtered for SW (black) and ripples (red). Bottom plots show the spike probability of Chns, PNs, and INs during SWs. Individual trials in gray and mean overlaid in color. The vertical dotted line marks the peak of the SW.

(H) Cell-type-specific AP discharge during a Chn evoked a SW in the network model (n = 16 trials). Note Chns and INs burst fire multiple APs, whereas PNs predominantly discharge a single AP.