Excitatory and inhibitory effects of HCN channel modulation on excitability of layer V pyramidal cells
Fig 1
Ih activation increases the frequency of action potentials in response to somatic DC in L5PCs.
A–B: The morphology of the Almog (A) and Hay (B) model neurons. C–D: Membrane potential time courses of the Almog (C) and Hay (D) model neurons. E–F: The frequency of APs (y-axis) in response to somatic DC of a given amplitude (x-axis) in Almog (E) and Hay (F) model neurons under up- or down-regulated Ih channels. Black: control neuron. Blue: Ih conductance blocked. Red: Ih conductance increased by 100%. G–H: The frequency of APs response to somatic DC in Almog (G) and Hay (H) model neurons under different neuromodulatory states. Black: control neuron. Blue: cAMP-inhibiting neuromodulation, modelled as a -5 mV (G) or -10 mV (H) shift in half-inactivation potential of the Ih channels. Red: cAMP-enhancing neuromodulation, modelled as a +5 mV (G) or +10 mV (H) shift in half-inactivation potential of the Ih channels. The insets of panels (E)–(H) show the threshold current amplitudes for inducing an AP. The relative changes to the threshold current amplitude of the control model are displayed next to the corresponding bars in the insets (the threshold current amplitudes can be different from the onsets of the f-I curves since some DC amplitudes only cause one spike). Note the difference in axes scales between the models in (E–H). Areas under curve, Almog model: 0.76 (Ih blocked), 3.1 (Ih under cAMP-inhibiting neuromodulation), 6.0 (control), 11.9 (Ih overexpressed), and 13.1 (Ih under cAMP-enhancing neuromodulation) nA⋅Hz. Areas under curve, Hay model: 14.0 (Ih blocked), 14.8 (Ih under cAMP-inhibiting neuromodulation), 15.2 (control), 15.6 (Ih overexpressed), 15.6 (Ih under cAMP-enhancing neuromodulation) nA⋅Hz.