Table 1.

Synaptic connectivity and strength

Subdivision			Connectivity			Peak amplitude (mV)
Synapse	Region	Layer	Found	Tested	Probability	Median [interquartile range]	n
PC–PC	Ventral	Superficial	2	746	0.3%a	0.33 [0.19;0.46]	2
		Deep	19	524	3.6%a	0.32 [0.14;0.47]	19
	Dorsal	Superficial	2	274	0.7%b	0.22 [0.13;0.31]o	2
		Deep	14	330	4.2%b	0.17 [0.1;0.25]p	14
PC–FS	Ventral	Superficial	23	124	18.5%g	2.31 [0.24;6.36]l	23
		Deep	10	60	16.7%	0.57 [0.21;2.22]	10
	Dorsal	Superficial	14	35	40.0%c,g	1.4 [0.58;3.31]j,m,o	14
		Deep	12	80	15.0%c	0.55 [0.22;0.705]j,p	12
PC–NFS	Ventral	Superficial	37	243	15.2%h	0.47 [0.22;1.78]k,l	37
		Deep	24	219	11.0%	0.43 [0.135;1.1]	24
	Dorsal	Superficial	27	104	26.0%d,h	0.18 [0.13;0.23]k,m	27
		Deep	11	87	12.6%d	0.36 [0.1;1.3]	11
FS–PC	Ventral	Superficial	32	124	25.8%	−0.33 [−0.77;−0.19]	18
		Deep	11	60	18.3%i	−0.13 [−0.17;−0.09]	2
	Dorsal	Superficial	7	35	20.0%e	−0.58 [−0.66;−0.52]n	7
		Deep	4	80	5.0%e,i	−0.42 [−0.51;−0.31]	4
NFS–PC	Ventral	Superficial	42	243	17.3%f	−0.2 [−0.68;−0.11]	23
		Deep	22	219	10.0%f	−0.28 [−0.38;−0.09]	15
	Dorsal	Superficial	19	104	18.3%	−0.19 [−0.33;−0.12]n	19
		Deep	7	87	8.0%	−0.18 [−0.28;−0.06]	7

The connection probability, calculated by the number of detected synaptic connections divided by the number of tested possible connections, is shown for different synaptic types, in the dorsal and ventral regions, and for the superficial and deep layers. Given the nonparametric distribution of the peak amplitudes of postsynaptic potentials, their central tendency and dispersion are depicted using the median and the interquartile range that is the interval from the 25th to the 75th percentile. Superscripts indicate P values below 0.05 of statistical comparisons between subgroups. Same superscripts indicate the 2 compared values. Due to correction for multiple comparisons using the Bonferroni method, the given P values are only statistically significant at α = 0.05 if they are below 0.013 for excitatory connections or below 0.017 for inhibitory connections. Statistical differences in connection probability were assessed using the Fisher's exact test. P values of layer comparison: a 0.011, b 0.009, c 0.007, d 0.028, e 0.033, and f 0.03. Region comparison: g 0.012, h 0.023, and i 0.014. Note that the excitatory connection probability onto PC is significantly lower than onto IN in all subgroups. Comparisons for postsynaptic amplitude were assessed using Mann–Whitney U test. P values for layer comparison: j 0.011. Region comparison: k < 0.001. Comparison between synaptic groups: l 0.031, m < 0.001, n 0.001, o 0.017, and p 0.011. See Supplementary Tables 1–5 for further statistics. Except for PC–PC connection probability, none of the other nonsignificant comparisons can be declared as statistically equivalent.