Synchronization-Induced Rhythmicity of Circadian Oscillators in the Suprachiasmatic Nucleus
Figure 2
Organization of the Circadian Oscillator Networks
(A) Random coupling (type 1). The probability that two oscillators are connected is independent of their positions.
(B) Nearest-neighbor coupling (type 2). Oscillators are on a grid with a Euclidian distance d. Circle representing oscillators are color-coded for their distance from the central black oscillator. Black, red, orange, blue, gray, and white circles are at distances d = 0, 1, , 2,
, and 2
, respectively. Two oscillators are connected if their distance is less than a threshold dmax.
(C) SCN-like coupling (type 3). The SCN is divided in four regions, left and right VL regions (dark blue and red, respectively), and left and right DM regions (light blue and red, respectively; the green part is the intersection between left and right DM regions). Each dot represents an oscillator. Projections from the VL regions to their respective DM regions are indicated by light gray arcs. Projections from one cell to another are assigned randomly, with probability 0.5 for a DM cell to receive a projection.
(D) Representation of a 3-D SCN. Each dot is a cell, and the color gradient indicates the VL–DM axis (dark cells are on the VL side and light cells are on the DM side, corresponding to the vertical axis in [C]). For type 3 coupling in a 3-D SCN, the regions are defined in the same way as in 2-D (C).