Fig. 3: α and β Cells are globally phase-locked during oscillation.

a Correlation matrix (Pearson correlation coefficients) for Ca²⁺ activity of Glu-Cre⁺;GCaMP6f^f/+;Ins2-RCaMP1.07 islet cells under 10 G stimulation. Cells are sorted according to cell types. β cells are indicated by the red bar, and α cells by the green bar. b The heat-map of time-dependent Ca²⁺ activity for α and β cells under 10 G stimulation. The color bar codes the normalized Ca²⁺ intensity. Each row represents the same cell in a. c Mean Ca²⁺ activity of α and β cells under 10 G stimulation for the same islet as a. Single-cell traces are shown with light lines. The red trace represents β cells and green trace α cells (n = 22 for β cells and n = 71 for α cells). d Mean Ca²⁺ activity of α and β cells in c, aligned at each β cell peak. Each trace starts from a peak of β cell oscillation and stops in the next peak. e Sequential activation of α and β cells under 10 G stimulation. We subtract the previous frame from the next frame of the original Ca²⁺ images and average across oscillations (each oscillation is aligned with the maximum activation frame). The mean activation sequence uses 5 min Ca²⁺ images (frame interval is 3 s). The β cells are colored red and α cells green. f Representative recordings of slow and mixed oscillations of Ca²⁺ activity of α and β cells under 10 G stimulation. Top: Slow oscillation; bottom: Mixed oscillation. The first column, maximal projection of Ca²⁺ masks (α cells green and β cells red); second column, mean Ca²⁺ trace of α and β cells (single-cell traces are shown with light lines); third column, heat-map of α and β cells’ Ca²⁺ activity. The color bar codes the normalized Ca²⁺ intensity.