Fig. 3

Monitoring of activity-driven Ca²⁺ dynamics in CStr circuits in the electrostimulable microfluidic device using Fluo5F-AM. A Representative Fluo5F-AM images of Ca²⁺ dynamics in response to neural activity (10 AP stimulus) at synapses of CStr circuits. Left, resting; middle, ∆F10AP; right, peak 10 AP. CStr circuits were incubated with Fluo5F-AM (5 μM) and stimulated with 10 APs at 100 Hz. Scale bar: 20 μm. B Kymograph images of Fluo5F-AM showing Ca²⁺ dynamics in response to 10-AP stimulation at the corresponding region of interest (ROI) in boutons in the synapse canal of the microfluidic chip. Arrow indicates initial point of stimulation. C Representative ensemble average Fluo5F-AM traces showing Ca²⁺ dynamics in response to microfluidic chip stimulation with 10 APs or 1 AP. D Ca²⁺ influx in arbitrary units (a.u.) in response to stimulation of the microfluidic chip with 10 APs or 1 AP, expressed as means ± SEM. [Ca²⁺]_10AP = 2.66 ± 0.43 a.u. (n = 12); [Ca²⁺]_1AP = 0.55 ± 0.08 a.u. (n = 12). E, F Distribution of Ca²⁺-influx responses to 10 APs (E; n = 586) and 1 AP (F; n = 587) in individual boutons. G Representative traces of Ca²⁺ dynamics in response to paired-pulse stimulation at different pulse intervals (50, 100, 200, and 500 ms). Arrows indicate the point of stimulation