Fig. 7
Distinct roles of PV and SST interneurons in gamma oscillogenesis and theta-nested gamma oscillation-induced tLTP. a Schematic diagram of CA3-CA1 hippocampal network model consisting of Hodgkin-Huxley-type computational models of CA1 PC, PV interneuron (PV model), SST interneuron (SST model), and a feedforward inhibition-mediating interneuron (IN model). The CA3 input activates IN and also provides excitation to the dendritic spine of the CA1 PC. b Firing rate plotted as a function of depolarizing current steps in 20 pA in PV interneuron (purple) and SST interneuron (green) recorded in vitro (empty circle, data from Additional file 4: Figure S4c, l), and that of the PV and SST models (filled circle). c Schematic of a deterministic [Ca2+]i-dependent spike timing-dependent plasticity (STDP) model. d A simulation of theta-nested gamma oscillation-induced tLTP. Oscillatory current (Itheta, 5 Hz, 20 pA) superimposed with a step current (Istep, 15 pA) was simulated to CA1 PC (top) to mimic gamma-frequency spikes in CA1 PC (middle). For tLTP induction, stimulation of CA3 input preceded the CA1 PC spikes by 10 ms, repeated at 5 Hz (bottom). e, f Representative raster plot of each neuron model with SST activation (e) or without SST activation (f). g Representative [Ca2+]i at CA1 PC spine during tLTP induction with SST activation (black) or without SST activation (red). h Change in the normalized synaptic weight of CA3-CA1 synapse plotted as a function of time with (black) and without SST activation (red)