Fig. 5: Interluminescence is dependent on presynaptic vesicle release.

a Schematics of synapses receiving synaptic blockers (SB) followed by electrical stimulation of presynaptic neurons together with CTZ application without (i) and after 48 h Botulinum Neurotoxin (BoNT) treatment (ii). b Representative trace of MEA recordings of opsin (ChR2(C128S)) expressing neurons without BoNT treatment (i, from Fig. 4diii) and 48 h after BoNT treatment of the co-culture (ii): electrical stimulation of presynaptic neurons together with CTZ application fails to elicit firing after BoNT treatment, while blue light still induces firing in the same recording. c Ladder plots of recording conditions as in (b) from electrodes across populations (comparisons are: spontaneous activity vs SB addition (after), n = 21, p < 0.0001; electrical stimulation (after) vs immediately following CTZ (after), n = 21, p = 0.7173; electrical stimulation + CTZ (after) vs blue light (before), n = 21, p = 0.6055; blue light (before) vs blue light (during), n = 21, p < 0.0001; Wilcoxon matched-pairs signed rank test). The artifacts due to addition of reagents in MEAs are overlaid by a vertical white bar in the recording traces (the white gap right after addition of SB or CTZ). Artifacts due to electrical stimulation are visible under the red bolts. ns, not significant; _****p < 0.0001.