Table 2.
Statistical models
| Model number, response variable, framework, link function, family | Explanatory variable | Coefficient | Statistic (n for z statistic or edf for t statistic) | p |
|---|---|---|---|---|
| 1, number of tips per basal tree, GEE, log link (quasi, variance function = mean) | Intercept | 2.15 ± 0.39 | z = 5.54 (110) | <0.001 |
| SP | 0.037 ± 0.095 | z = 0.39 (110) | 0.693 | |
| DEP | −0.054 ± 0.103 | z = −0.52 (110) | 0.600 | |
| Age | 0.006 ± 0.007 | z = 0.77 (110) | 0.441 | |
| Number basal trees | −0.12 ± 0.03 | z = −4.63 (110) | <0.001 | |
| 2, dendrite intersections, GAM, identity link, Gaussian | Intercept | 8.4 ± 2.3 | t = 3.57 (473) | <0.001 |
| f (path length) | N/A | F = 260 (edf = 7.8) | <0.001 | |
| SP | 0.92 ± 0.63 | t = 1.46 (473) | 0.146 | |
| DEP | 0.60 ± 0.67 | t = 0.90 (473) | 0.371 | |
| Age | 0.15 ± 0.05 | t = 2.92 (473) | 0.004 | |
| 3, basal terminal segment path length, GEE, identity link, Gaussian | Intercept | 131.4 ± 11.6 | z = 11.4 (315) | <0.001 |
| SP | 0.01 ± 4.7 | z = 0.002 (89) | 0.999 | |
| DEP | −7.1 ± 3.4 | z = −2.08 (106) | 0.037 | |
| Branch order | −8.3 ± 1.4 | z = −6.04 (315) | <0.001 | |
| Number of basal tips | −0.32 ± 0.32 | z = −1.03 (315) | 0.301 | |
| 4, basal terminal segment path length, GEE, identity link, Gaussian (interaction model) | Intercept | 130.4 ± 11.4 | z = 11.5 (315) | <0.001 |
| SP × age | 0.04 ± 0.12 | z = 0.36 (89) | 0.719 | |
| DEP × age | −0.16 ± 0.08 | z = −1.99 (106) | 0.047 | |
| Branch order | −8.1 ± 1.4 | z = −5.81 (315) | <0.001 | |
| Number of basal tips | −0.33 ± 0.32 | z = −1.03 (315) | 0.303 | |
| 5, path length to terminal branch point, GEE, log link (quasi, variance function = mean) | Intercept | 2.63 ± 0.28 | z = 9.3 (315) | <0.001 |
| SP | −0.13 ± 0.06 | z = −2.38 (89) | 0.017 | |
| DEP | −0.12 ± 0.06 | z = −2.12 (106) | 0.033 | |
| Branch order | 0.24 ± 0.02 | z = −14.2 (315) | <0.001 | |
| Number of basal trees | −0.12 ± 0.03 | z = −4.11 (315) | <0.001 | |
| Age | 0.013 ± 0.006 | z = 2.15 (315) | 0.032 | |
| 6, peak basal spine density, GEE, identity link, Gaussian | Intercept | 1.97 ± 0.18 | z = 10.9 (120) | <0.001 |
| SP | −0.12 ± 0.07 | z = −1.65 (40) | 0.099 | |
| DEP | −0.25 ± 0.07 | z = −3.71 (40) | <0.001 | |
| Age | −0.012 ± 0.003 | z = −3.42 (120) | <0.001 | |
| 7, peak basal spine density, GEE, identity link, Gaussian (interaction model) | Intercept | 1.88 ± 0.17 | z = 11.3 (120) | <0.001 |
| (SP × age) | −0.003 ± 0.002 | z = −1.96 (40) | 0.050 | |
| (DEP × age) | −0.006 ± 0.001 | z = −4.09 (40) | <0.001 | |
| Age | −0.010 ± 0.003 | z = −2.97 (120) | 0.003 | |
| 8, apical spine density, GAM, identity link, Gaussian | Intercept | 1.61 ± 0.16 | t = 10.3 (253) | <0.001 |
| f (path length) | NA | F = 1.49 (edf = 2.8) | 0.182 | |
| SP | 0.013 ± 0.055 | t = 0.23 (253) | 0.817 | |
| DEP | 0.001 ± 0.059 | t = 0.02 (253) | 0.981 | |
| Age | −0.006 ± 0.003 | t = 1.85 (253) | 0.066 | |
| 9, total axonal length in regions of proximity, GLM, log link (quasi, variance function = mean2) | Intercept | 3.03 ± 0.87 | t = 3.46 (41) | 0.001 |
| (SP × conn) | 1.12 ± 0.37 | t = 3.04 (41) | 0.004 | |
| (SP × unconn) | −0.27 ± 0.38 | t = −0.71 (41) | 0.482 | |
| DEP | 0.68 ± 0.47 | t = −1.43 (41) | 0.161 | |
| Age | 0.01 ± 0.02 | t = 0.74 (41) | 0.466 | |
| Intersomatic distance | 0.002 ± 0.005 | t = −0.45 (41) | 0.656 | |
| 10, axonal varicosity density, GEE, inverse link, gamma family | Intercept | 1.09 ± 0.13 | z = 8.37 (168) | <0.001 |
| SP | −0.19 ± 0.07 | z = −2.63 (126) | 0.008 | |
| Basal | 0.09 ± 0.04 | z = 2.27 (103) | 0.023 | |
| Age | 0.003 ± 0.003 | z = 1.08 (168) | 0.281 | |
| 11, proportion of terminaux varicosities, GEE, identity link, Gaussian family | Intercept | 0.101 ± 0.023 | z = 4.46 (98) | <0.001 |
| (SP × conn) | 0.025 ± 0.012 | z = 2.07 (52) | 0.038 | |
| (SP × unconn) | 0.053 ± 0.013 | z = 4.25 (11) | <0.001 | |
| (CNTRL × unconn) | −0.002 ± 0.013 | z = −0.13 (20) | 0.889 | |
| Age | 0.0006 ± 0.0005 | z = −1.25 (98) | 0.212 |
Statistical models were classified as generalized linear model (GLM), generalized additive model (GAM), or generalized estimating equations (GEE). Model variables were as follows: number of basal trees, number of basal trees originating from the L2/3 pyramidal neuron soma; intersections, number of intersections with a Sholl shell; path length, path length from the soma; CNTRL, control cortex; age, age in postnatal days; branch order, order of the terminal dendritic branch; number of basal tips, total number of basal dendritic endings for the L2/3 pyramidal neuron; path length to terminal branch point, path length to the point where the terminal segment originates; peak basal spine density, spine count per μm on basal dendrites 50–70 μm from the soma; apical spine density, spine count per micrometer on the apical main stem dendrite; number of basal trees, number of basal dendritic trees on an L2/3 pyramidal neuron; conn, presence of a synaptic connection between the axon of the presynaptic pyramidal neuron with the postsynaptic pyramidal neuron that has been demonstrated electrophysiologically; unconn, electrophysiological testing did not demonstrate evidence for a synaptic connection between the axon of the putative presynaptic pyramidal neuron with the postsynaptic pyramidal neuron; intersomatic distance, distance between the somata of two pyramidal neurons; basal, basal dendrite in RoP; edf, estimated degrees of freedom for explanatory variables that are used as functions in generalized additive models; NA, not applicable.