αCaMKII translocates to dendritic sites of higher Ca²⁺ concentration. (A) Neurons expressing mCherry-αCaMKII and GCaMP2 stimulated for 5 min with 0Mg²⁺/Gly (Ai, iii) or (B) stimulated by local puffs (10-ms puffs at 2 Hz during 13 min) of Glu/Gly (100/10 µM; Bi, iii). Brackets indicate CaMKII dendritic hot spots (D+, white) or adjacent dendritic region (D−, red). (Aii and Bii) Kymograph of the change in intensity of GCaMP2 and mCherry-αCaMKII over time across the dendritic region shown above (white line). Stimulation period is indicated (0Mg²⁺/Gly or Puffs). (Aiv and Biv) Time-lapse analysis of mCherry-αCaMKII (purple) and GCaMP2 (green) intensity in a region of dendritic CaMKII translocation (D+, top graph) or in an adjacent region (D−, bottom graph). (Av and Bv) Mean (±SEM) ΔF/F₀ (in paired regions as in ii–iii) of mCherry-αCaMKII (purple) and GCaMP2 (green) during the first 5 min of stimulation. (Aiv) n = 12 neurons, 52 dendritic segments. (Biv) n = 5 neurons, 5 dendritic segments. Bars: (neurons) 10 µm; (dendrites) 5 µm. *, P < 0.01 paired t test. See also Video 4.