Table 3.

Densities of synapses in the neuropil

	Layer
	I	II	III	IV	V	VI	Avg
Density of all synapses (AS+SS)	0.83	1.13	0.94	1.16	0.83	0.47	0.89
Percent synapses on spines	76.13	86.57	79.58	76.94	75.61	74.36	78.20
Percent synapses on shafts	23.87	13.43	20.42	23.06	24.39	25.64	21.80
Density of synapses on spines	0.63	0.98	0.75	0.89	0.63	0.35	0.70
Density of synapses on dendritic shafts	0.20	0.15	0.19	0.27	0.20	0.12	0.19
Density of AS synapses	0.73	1.05	0.86	1.02	0.76	0.40	0.81
Percent AS on spines	82.44	90.56	85.10	82.63	81.17	79.80	83.62
Percent AS on shafts	17.56	9.44	14.90	17.37	18.83	20.20	16.38
Density of AS on spines	0.61	0.95	0.73	0.84	0.62	0.32	0.68
Density of AS on dendritic shafts	0.13	0.10	0.13	0.18	0.14	0.08	0.13
Density of SS synapses	0.10	0.08	0.08	0.14	0.07	0.06	0.09
Percent SS on spines	32.00	22.81	14.12	37.82	16.07	30.00	25.47
Percent SS on shafts	68.00	77.19	85.88	62.18	83.93	70.00	74.53
Density of SS on spines	0.03	0.02	0.01	0.05	0.01	0.02	0.02
Density of SS on dendritic shafts	0.07	0.06	0.07	0.09	0.06	0.04	0.06

Density of synapses (as no. of synapses/μm³) and percentage of asymmetric (AS) and symmetric synapses (SS) on spines and dendritic shafts in the neuropil of the six cortical layers (I–VI). Average values (Avg) are given in the column on the right. See also Supplementary Table 1 in Online Resource 1