$\frac{\mathrm{Ca}^n}{\mathrm{Ca}^n+\mathrm{K\_mN}^n(1+\frac{\mathrm{K\_dN}}{M})}$ $\begin{cases}\mathrm{act\_N} & \text{if $t< \mathrm{tNinhib}$}\\ \mathrm{act\_N}e^{\left(\frac{-(t-\mathrm{tNinhib})}{\mathrm{tau\_actN}}\right)} & \text{if $t\ge \mathrm{tNinhib}$}\end{cases}$