Table 2. List of membrane-proximal (MP)-synaptic vesicle (SV) parameters showing the mean ± SEM values, N, n, p-values and the statistical tests applied.

Data are presented as mean ± SEM. Data was tested for significant differences by one-way ANOVA followed by Tukey’s test (parametric data) or Kruskal-Wallis (KW) test followed by Dunn’s test (non-parametric data). Significant results are indicated with *p<0.05; **p<0.01; ***p<0.001; and ****p<0.0001.

		B6J Light	ChR2 NoLight	ChR2 ShortStim	ChR2 LongStim	Adjusted p-value	Test
N animals		2	4	1	4
nribbons Total		15	17	11	26
nribbons Ai32VC			9	11	15
nribbons Ai32KI			8	0	11
nSV Total		146	253	132	311
nSV Non-tethered		38	60	20	75
nSV Tethered		107	191	99	175
nSV Docked		1	2	13	61
MP-SVs count		9.73	14.88	12.00	11.96	**; B6J Light vs. ChR2 NoLight	KW test – Dunn’s test
		±0.796	±0.935	±1.844	±0.833	0.0028
Fraction of non-tethered SVs		0.28	0.23	0.14	0.24	*; B6J Light vs. ChR2 ShortStim	ANOVA – Tukey’s test
		±0.035	±0.026	±0.035	±0.026	0.0271
Fraction of tethered SVs		0.72	0.75	0.77	0.57	*; B6J Light vs. ChR2 LongStim	ANOVA – Tukey’s test
		±0.033	±0.025	±0.049	±0.034	0.0151
						***; ChR2 LongStim vs. ChR2 NoLight
						0.0008
						**; ChR2 LongStim vs. ChR2 ShortStim
						0.002
Fraction of docked SVs		0.01	0.01	0.10	0.20	****; B6J Light vs. ChR2 LongStim	KW test – Dunn’s test
		±0.006	±0.009	±0.034	±0.025	<0.0001
						****; ChR2 LongStim vs. ChR2 NoLight
						<0.0001
Fraction of tethered	Single PM tethered	0.25	0.30	0.18	0.25	n.s.	ANOVA – Tukey’s test
		±0.052	±0.039	±0.055	±0.036
	Single PD tethered	0.12	0.12	0.02	0.13	n.s.	KW test – Dunn’s test
		±0.046	±0.029	±0.013	±0.032
	Interconnected	0.02	0.02	0.04	0.05	n.s.	KW test – Dunn’s test
		±0.01	±0.009	±0.023	±0.029
	Multiple tethered	0.61	0.56	0.76	0.56	n.s.	ANOVA – Tukey’s test
		±0.068	±0.051	±0.048	±0.046
Distance to the membrane	All MP-SVs	22.78	23.67	19.41	19.61	***; ChR2 LongStim vs. ChR2 NoLight	KW test – Dunn’s test
		±1.08	±0.776	±1.263	±0.876	0.0007
						*; ChR2 NoLight vs. ChR2 ShortStim
						0.0105
	Non-tethered	32.42	31.81	31.32	30.06	n.s.	KW test – Dunn’s test
		±2.138	±1.655	±3.172	±1.481
	Tethered	19.56	21.36	19.51	21.94	n.s.	KW test – Dunn’s test
		±1.077	±0.789	±1.292	±0.982
	Docked	1.44	0.00	0.34	0.09	Not tested: low n of docked SVs in control and NoLight conditions
		±0	±0	±0.18	±0.053
Distance to the PD	All MP-SVs	31.88	37.61	32.96	30.13	***; ChR2 LongStim vs. ChR2 NoLight	KW test – Dunn’s test
		±2.144	±1.622	±2.192	±1.509	0.0001
	Non-tethered	35.49	47.09	45.34	38.07	0.0502	KW test – Dunn’s test
		±4.386	±3.321	±3.654	±3.124
	Tethered	30.12	34.52	34.12	31.49	n.s.	KW test – Dunn’s test
		±2.426	±1.808	±2.571	±1.975
	Docked	83.27	48.46	5.06	16.43	Not tested: low n of docked SVs in control and NoLight conditions
		±0	±35.88	±1.892	±2.876
Diameter of SVs	All MP-SVs	49.00	48.67	49.17	48.05		KW test – Dunn’s test
		±0.442	±0.25	±0.352	±0.303
	Non-tethered	50.17	49.71	53.27	48.76	**; B6J Light vs. ChR2 ShortStim	KW test – Dunn’s test
		±1.061	±0.63	±0.835	±0.485	0.0093
						***; ChR2 LongStim vs. ChR2 ShortStim
						0.0004
						**; ChR2 NoLight vs. ChR2 ShortStim
						0.0069
	Tethered	48.55	48.29	48.06	47.76	n.s.	KW test – Dunn’s test
		±0.465	±0.259	±0.359	±0.419
	Docked	53.70	53.70	51.29	47.97	Not tested: low n of docked SVs in control and NoLight conditions
		±0	±0	±0.845	±0.773