Figure 3. Propagating Ca²⁺ Signals Are LTCC-Mediated, Forward Propagating Ca²⁺ Spikes.

(A) Neuron transfected with GCaMP6f (inverted grayscale) indicating location of distal spine 1 Hz-GU (20 pulses; cross) during simultaneous whole-cell current clamp recording at the soma. Scale bar, 20 μm.

(B) Representative GCaMP6f ΔF/F₀ traces taken from ROIs drawn at the uncaged spine (top) and soma (middle) with current clamp recording trace (bottom) following 1 Hz-GU (with 1 μM TTX in the bath).

(C) Expanded view of 3 responses in current clamp trace indicated with an asterisk (*) in (B).

(D) Averaged traces of 24 spikes from 5 neurons. THOLD, threshold (mV); ½ max, width at half maximum (ms); AMP, amplitude (mV).

(E) Representative traces following 1 Hz-GU from another neuron, as described in (A) and (B).

(F) GCaMP6f and current clamp traces from neuron shown in (E) following bath addition of nim (5 μM).

(G) Spine-integrated GCaMP6f ΔF/F₀ before and after nim.

(H) ΔV plateau in current clamp trace before and after nim.

(I) Soma-integrated GCaMP6f ΔF/F₀ before and after nim.

(J) Number of spikes before and after nim (G–J: n = 7; paired t test, *p < 0.05).

See also Figure S3.