A mathematical model for the role of dopamine-D2 self-regulation in the production of ultradian rhythms
Fig 8
Circadian-ultradian interaction enhances responsiveness to transient stimulus.
Simulated DAex trajectories (black line) of the DUSR model with an inhibitory circadian signal (yellow curve) and a transient excitatory pulse (vertical red line). A: The effect of a transient excitatory pulse on the DUSR model is amplified by the circadian inhibitory signal. Plotted from top to bottom are the DAex response trajectories to (I) an excitatory pulse of the DUSR model, (II) DUSR with a constant inhibitory signal, (III) with a circadian inhibitory signal, (IV) with a masking circadian inhibitory signal, (V) with a circadian inhibitory signal and the ultradian DA feedback loop fixed so that D2AR and TDA are held constant and DAex decreases in scale. B: Effect of an identical transient excitatory pulse given at the same phase of on DAex under increasing circadian regulation. C: Effect of an identical transient excitatory pulse given at different circadian phases on DAex.