Figure 4. Manipulations of synaptic strength ($\mathit{N}·{\mathit{P}}_{\mathit{S}\mathit{y}\mathit{n}}·\frac{1}{2}{\mathit{W}}_{\mathit{m}\mathit{a}\mathit{x}}$) and ${\stackrel{-}{\mathit{g}}}_{\mathit{C}\mathit{A}\mathit{N}}$ have equivalent effects on network activity amplitude, frequency and recruitment of inspiratory neurons not involved in rhythm generation.

(A and B) Relationship between ${\stackrel{-}{\mathit{g}}}_{\mathit{C}\mathit{A}\mathit{N}\mathit{}}$ (mean values for the simulated populations), synaptic strength and the amplitude and frequency in the ${\mathit{C}\mathit{a}}_{\mathit{S}\mathit{y}\mathit{n}}$ network. Notice the symmetry about the X=Y line in panels A and B, which, indicates that changes in ${\stackrel{-}{\mathit{g}}}_{\mathit{C}\mathit{A}\mathit{N}}$ and or synaptic strength are qualitatively equivalent. Synaptic strength was changed by varying ${\mathit{W}}_{\mathit{m}\mathit{a}\mathit{x}}$. (C) Relationship between network activity amplitude and the reduction of ${\stackrel{-}{\mathit{g}}}_{\mathit{C}\mathit{A}\mathit{N}}$ (blue) or synaptic strength (green). (D) Relationship between network frequency and the reduction of ${\stackrel{-}{\mathit{g}}}_{\mathit{C}\mathit{A}\mathit{N}}$ (blue) or synaptic strength (green). (E and F) Decreasing ${\stackrel{-}{\mathit{g}}}_{\mathit{C}\mathit{A}\mathit{N}}$ or synaptic strength de-recruits neurons by reducing the inspiratory drive potential, indicated by the amplitude of subthreshold depolarization, right traces. The solid blue and green lines in panels A and B represent the location in the 2D parameter space of the corresponding blue and green curves in C and D. The action potentials in the right traces of E and F are truncated to show the change in neuronal inspiratory drive potential. The parameters used for these simulations are ${\mathit{C}\mathit{a}}_{\mathit{S}\mathit{y}\mathit{n}}$: ${\stackrel{-}{\mathit{g}}}_{\mathit{C}\mathit{a}}=\left[\mathrm{0,0}\right]$, ${\mathit{P}}_{\mathit{C}\mathit{a}}=0.01$, ${\mathit{P}}_{\mathit{S}\mathit{y}\mathit{n}}=1.0$ and ${\mathit{W}}_{\mathit{m}\mathit{a}\mathit{x}}=\mathit{v}\mathit{a}\mathit{r}$.