Fig. 3.

The effect of tryptophan input. a Shows the steady state values of vesicular serotonin, vht (blue curve), and extracellular serotonin, eht (red curve), over a range of values of blood tryptophan ($96\mathrm{\mu }\text{M}$ being normal) if the autoreceptors are turned off. b Shows the analogous curves if the autoreceptor effect is normal. The vht curve varies much more and the eht curve varies much less (for explanation, see the text). c Shows the effect of three daily meals on the extracellular concentration of eht with no autoreceptor effect (red curve) and normal autoreceptors (green curve). The autoreceptors greatly dampen the fluctuations of eht due to meals