Resetting behavior in a model of bursting in secretory pituitary cells: distinguishing plateaus from pseudo-plateaus.
We study a recently discovered class of models for plateau bursting, inspired by models for endocrine pituitary cells. In contrast to classical models for fold-homoclinic (square-wave) bursting, the spikes of the active phase are not supported by limit cycles of the frozen fast subsystem, but are transient oscillations generated by unstable limit cycles emanating from a subcritical Hopf bifurcation around a stable steady state. Experimental time courses are suggestive of such fold-subHopf models because the spikes tend to be small and variable in amplitude; we call this pseudo-plateau bursting. We show here that distinct properties of the response to attempted resets from the silent phase to the active phase provide a clearer, qualitative criterion for choosing between the two classes of models. The fold-homoclinic class is characterized by induced active phases that increase towards the duration of the unperturbed active phase as resets are delivered later in the silent phase. For the fold-subHopf class of pseudo-plateau bursting, resetting is difficult and succeeds only in limited windows of the silent phase but, paradoxically, can dramatically exceed the native active phase duration.
Stern
Julie V
JV
Laboratory of Biological Modeling, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA.
Osinga
Hinke M
HM
LeBeau
Andrew
A
Sherman
Arthur
A
D000818:Animals; D001683:Biological Clocks / Q000502:physiology; D020013:Calcium Signaling / Q000502:physiology; D008564:Membrane Potentials / Q000502:physiology; D008954:Models, Biological; D009716:Numerical Analysis, Computer-Assisted; D010902:Pituitary Gland / Q000166:cytology / Q000502:physiology*; D051381:Rats