Table1.

Summary of statistical analyses

Figure, statistical test, and measure
Fig. 1B
Quantitative real-time PCR		GPHR^F/FAV: GFP			GPHR^F/FAV: Cre
unpaired Student’s t test		mRNA levels of GPHR			mRNA levels of GPHR
		Mean	SEM	n	Mean	SEM	n	Statistics
Relative mRNA levels		0.992	± 0.025	6	0.044	± 0.011	6	p < 0.0001
Fig. 1D
Intensity of pHluorin		GPHR^F/+AV: Cre			GPHR^F/FAV: Cre
unpaired Student’s t test		Mean	SEM	n	Mean	SEM	n
Raito (pHluorin/mKate2; 488/562 nm)		1.015	± 0.038	5	1.390	± 0.068	5	p = 0.0013
Fig. 2B
Rotarod test
One-way ANOVA followed by		GPHR^F/+;GluD2-Cre			GPHR^F/F;GluD2-Cre
Sidak’s multiple comoarusins test	Age	Mean	SEM	n	Mean	SEM	n	Statistics
Time (s)	P45	247.8	± 15.39	5	242.7	± 16.46	5	p = 0.9956
	P60	231.0	± 23.67	5	207.5	± 16.56	5	p = 0.7158
	P90	226.9	± 16.53	5	146.4	± 12.10	5	p = 0.0086
Fig. 2D
Composite phenotype scoring system
Kruskal–Wallis rank sum test		GPHR^F/+;GluD2-Cre			GPHR^F/F;GluD2-Cre
followed by Dunn's test	Age	Mean	SEM	n	Mean	SEM	n	Statistics
Average score	P45	0	0	9	0.222	± 0.147	9	p > 0.9999
	P60	0.333	± 0.167	9	0.667	± 0.167	9	p > 0.9999
	P90	0.333	± 0.167	9	3.78	± 0.222	9	p = 0.0087
	P150	0.222	± 0.147	9	5.667	± 0.236	9	p < 0.0001
	P300	0.444	± 0.176	9	6.333	± 0.441	9	p = 0.0002
Fig. 3B
Measurement of cerebellar area
One-way ANOVA followed by		GPHR^F/+;GluD2-Cre			GPHR^F/F;GluD2-Cre
Sidak’s multiple comoarusins test	Age	Mean	SEM	n	Mean	SEM	n	Statistics
Area (mm²)	P60	7.405	± 0.0449	15	6.883	± 0.0816	15	p = 0.0009
	P90	7.340	± 0.0569	15	6.127	± 0.0974	15	p < 0.0001
Fig. 3E
Quantitative analysis of PC density
One-way ANOVA followed by		GPHR^F/+;GluD2-Cre			GPHR^F/F;GluD2-Cre
Sidak’s multiple comoarusins test	Age	Mean	SEM	n	Mean	SEM	n	Statistics
PC/µm²	P45	0.0150	± 0.00068	15	0.01467	± 0.00052	15	p = 0.9213
	P60	0.0147	± 0.00093	15	0.01261	± 0.00049	15	p = 0.0002
	P90	0.0158	± 0.00117	15	0.00562	± 0.00120	15	p < 0.0001
Related to Fig. 3F
Quantitative analysis of IBA1-positive		GPHR^F/+;GluD2-Cre			GPHR^F/F;GluD2-Cre
Microglia	Age	Mean	SEM	n	Mean	SEM	n	Statistics
Unpaired Student’s t test	P60	35.69	± 2.70	15	97.730	± 7.86	15	p < 0.0001
Microglia/nm²
Related for Fig. 4A
Quantitative analysis of the abnormal		GPHR^F/F;GluD2-Cre
Golgi in PC	Age	Mean	SEM	n				Statistics
Unpaired Student’s t test	P45	66.85	± 3.13	15				P45 vs P60
Ratio (abnormal Golgi distribution within	P60	90.58	± 2.23	15				p < 0.0001
PC/total number of PCs)
Related to Fig. 5A
Quantitative analysis of axonal swelling		GPHR^F/F;GluD2-Cre
in granule cell layer	Age	Mean	SEM	n				Statistics
unpaired Student’s t test	P45	40.04	± 3.00	15				P45 vs P60
Size of axon swelling (µm²)	P60	70.22	± 4.64	15				p = 0.0241
		GPHR^F/F;GluD2-Cre
	Age	Mean	SEM	n				Statistics
Density of axon swellings/nm²	P45	56.54	± 4.94	15				P45 vs P60
	P60	80.19	± 8.59	15				p < 0.0001

Related to Fig. 5C
Quantitative analysis of axonal swelling		GPHR^F/F;GluD2-Cre
in DCNs	Age	Mean	SEM	n				Statistics
Unpaired Student’s t test	P45	261.10	± 32.54	15				P45 vs P60
Density of axon swellings/nm²	P60	880.60	± 46.07	15				p < 0.0001
Related to Fig. 6A
Pinceau structure counting
One-way ANOVA followed by		GPHR^F/+;GluD2-Cre			GPHR^F/F;GluD2-Cre
Sidak’s multiple comoarusins test	Age	Mean	SEM	n	Mean	SEM	n	Statistics
Raito (total number of PC with	P60	89.58	± 1.591	15	17.92	± 1.50	15	p < 0.0001
Pinceau structure/total number of PCs)
		GPHR^F/+;GluD2-Cre			GPHR^F/F;L7-Cre
	Age	Mean	SEM	n	Mean	SEM	n	Statistics
	P60	89.58	± 1.591	15	87.46	± 1.50	15	p = 0.7015
		GPHR^FF+;GluD2-Cre			GPHR^F/F;L7-Cre
	Age	Mean	SEM	n	Mean	SEM	n	Statistics
	P60	17.92	± 1.50	15	87.46	± 1.50	15	p < 0.0001
Fig. 7C,D
Electrophysiological analysis
Unpaired Student’s t test		GPHR^F/+;GluD2-Cre			GPHR^F/F;GluD2-Cre
		Mean	SEM	n	Mean	SEM	n	Statistics
Frequency (Hz)	All	1.340	± 0.1135	4	0.892	± 0.2242	4	p = 0.1258
	Small	0.9030	± 0.0460	4	0.727	± 0.1690	4	p = 0.3542
	Large	0.4360	± 0.0833	4	0.165	± 0.0680	4	p = 0.0454
		Mean	SEM	n	Mean	SEM	n	Statistics
Amplitude (pA)	All	99.82	± 3.57	4	73.15	± 7.81	4	p = 0.0210
	Small	70.00	± 4.97	4	61.16	± 3.99	4	p = 0.2147
	Large	162.60	± 19.87	4	138.90	± 6.17	4	p = 0.2994
Related to Fig. 8A
vGlut2 positive puncta on PC soma
One-way ANOVA followed by		GPHR^F/+;GluD2-Cre			GPHR^F/F;GluD2-Cre
Sidak’s multiple comoarusins test	Age	Mean	SEM	n	Mean	SEM	n	Statistics
Raito (vGlut2-positive puncta with PC	P60	9.95	± 1.07	15	69.02	± 4.21	15	p < 0.0001
somata/total number of PCs)
		GPHR^F/+;GluD2-Cre			GPHR^F/F;L7-Cre
	Age	Mean	SEM	n	Mean	SEM	n	Statistics
	P60	9.95	± 1.07	15	15.06	± 1.300	15	p = 0.4383
		GPHR^F/F;GluD2-Cre			GPHR^F/F;L7-Cre
	Age	Mean	SEM	n	Mean	SEM	n	Statistics
	P60	69.02	± 4.21	15	15.06	± 1.300	15	p < 0.0001
Related to Fig. 8B
mGluR1α-vGlut2 double-positive puncta		GPHR^F/+;GluD2-Cre			GPHR^F/F;GluD2-Cre
on PC soma	Age	Mean	SEM	n	Mean	SEM	n	Statistics
Unpaired Student’s t test	P60	9.34	± 1.26	15	45.73	± 4.02	15	p < 0.0001
Raito (vGlut2-positive puncta with PC
somata/total number of PCs)
Related to Fig. 9
Quantitative analysis of
lamellar body density		GPHR^F/+;GluD2-Cre			GPHR^F/F;GluD2-Cre
Unpaired Student’s t test	Age	Mean	SEM	n	Mean	SEM	n	Statistics
Lamellar body/nm	P60	0.29	± 0.06	5	6.49	± 0.55	5	p < 0.0001