Pyramidal-OLM cells network generates theta through two mechanisms.

<p>A) Schematic showing the pyramidal-OLM cells network with weak pyramidal to OLM synapses (weight set to 2), used in panels B-D. B) Spike raster plot of OLM spikes (B1). The OLM inhibitory currents received by one example pyramidal cell (B2). Note that inhibitory currents occur at a frequency much lower than theta. Spike raster plot of pyramidal cells spikes (B3). C) The population power spectrum of OLM cells (C1), and pyramidal cells (C2). Spectrum averaged from 10 instantiations of the network, shaded areas represent SD. D1) The pyramidal cell spike-triggered average of the adaptation current (dashed red line) and received OLM inhibition (solid blue line). Note that OLM inhibition showed a poor association with pyramidal cells spikes. D2) the inter-spike interval distribution of pyramidal cells remains largely unchanged from freely spiking pyramidal cells (compare with <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0182648#pone.0182648.g004" target="_blank">Fig 4C3</a>). E) Schematic showing the network with strong pyramidal to OLM synapses (weight set to 6), used in panels F-H. F1) Spike raster plot of OLM spikes. F2) The OLM inhibitory currents received by one example pyramidal cell. F3) Spike raster plot of pyramidal cells spikes. G) The population power spectrum of OLM cells (G1), and pyramidal cells (G2). H) The pyramidal cell spike-triggered average (H1) of the adaptation current (dashed red line) and received OLM inhibition (solid blue line). Note the close association between OLM inhibition and pyramidal cells spikes. Note that OLM inhibition changes the distribution of the pyramidal cells inter-spike intervals (H2), creating a peak around 110 ms. Power spectrum peaks: C1,2: 6 Hz. G1,2: 8 Hz.