Fig. 7

Oscillations in the model. For many sets of parameters different from those in “Methods” section, the model shows oscillations. The curves in Fig. 7, which show oscillations with a period of about 25 s, were obtained by changing parameters as follows. We increased strength of the inhibitory effect of the autorecetors on release to inhib(G ^∗) = (7.645−10∗G ^∗), and similarly increased the effect on synthesis in the formula for V _HTDC. We also increased the speeds of Eqs. (8) and (9) by multiplying the right hand sides by 5 and decreased the speed of Eq. (10) by multiplying the right hand side by 0.3. The steady state of the system remains the same, but all four variables, show oscillations, as seen in panels a (eHA and bHA) and b (G ^∗ and T ^∗)