A mathematical model for the role of dopamine-D2 self-regulation in the production of ultradian rhythms
Fig 5
Circadian regulation on the ultradian rhythm.
The effect of an inhibitory circadian-signal input (yellow line) Rcirc to V0 on extracellular dopamine concentration DAex (black line) over time. A: Circadian inputs of different waveforms consolidate ultradian DA episodes within a circadian active phase. B: Increasing the circadian signal’s strength substitutes its consolidating effect on the ultradian rhythm with a complete masking effect. C: Circadian-signal modification has a bidirectional effect on the ultradian rhythm. Depending on the DUSR system’s intrinsic oscillatory state, removal of circadian regulation results in either a more pronounced ultradian rhythm (upper panel) or the loss of quasi-ultradian episodes (lower panel).