Fig 1.
(A) The general structure of the model includes a large number of sleep units (filled circles) interacting with the central sleep-wake switch. Some of them (filled with magenta) form an active ensemble, receiving a common psycho-sensory drive. (B) The structure of the central sleep-wake switch model follows [41,42]. The bar-headed and arrow-headed lines indicate inhibitory and excitatory connections, respectively. The abbreviations are: P - photoreceptors, SCN - suprachiasmatic nucleus of the hypothalamus, H - homeostatic process, MA - monoaminergic nuclei of the hypothalamus and brainstem, VLPO - ventrolateral preoptic nucleus of the hypothalamus. (C) The structure of the rate model of the individual sleep unit. The abbreviations are: TPS - total postsynaptic signal, NRA - neuronal rate activity, ACA - astrocyte calcium activity, BFA - blood flow activity, AGR - astrocytic glycogen reserves, NAR - noradrenaline release, PSD - psycho-sensory drive, FNET - inputs from functional network, LBI - lateral background inputs. For details see text.
Fig 2.
Time courses of variables ,
and H with a 15-minute change of the parameters Am (at 15:00 by 25%) and
(at 17:00 by 15%). Sleep state is shown in light purple. The model demonstrates that stimulation causes daytime sleep lasting 2 hours.
Fig 3.
Block diagram of a single Sleep Unit model.
Fig 4.
On the behavior of an individual sleep unit.
Graphs of selected model variables show the response to an excessively strong stimulus (red arrows) and to a “normally high” noise-like stimulus (black arrows). For further details see text.
Fig 5.
Averaged activity of an ensemble.
An ensemble include of 100 sleep units as a function of the parameters knet and PSDinputs, which specify the strength of excitatory connections within the ensemble and the percentage of units receiving an external PSD signal, respectively. (A) Sketch of the diagram showing the regions of the main modes. (B) and (C) The change of mode along the dashed lines B and C in panel A, respectively. (D) A similar signal obtained by replacing the ensemble with a single sleep unit equipped with positive feedback. For further details see the text.
Fig 6.
Block diagram of the relationship between the parts of the model, describing the global (top) and local (bottom) parts. On the right are the time dependencies of the variables of the original model and the local model. See text for details.
Fig 7.
Scenario modeling. Time realizations of variables and H.
Parameter values. (A) ,
,
; (B)
,
,
; (C)
,
,
; (D)
,
,
; (E) as for panel B, but PSD signal was applied one hour later, from t = 4.75 till t = 5.0.