Table 3

Statistical Comparisons for 2D Transmission Electron Microscopy (TEM) and 3D Focused Ion Beam Scanning Electron Microscopy (FIBSEM) Analyses.

ComparisonTestn (animals, total sampled structures)% ChangePower(post-hoc, two-tailed)p value
Synapse Length
All AgesANOVA, one-way6.7 x 10-7*
>p90 vs. p60-66Bonferroni post hoc t Test, two-tailed>p90 (3, 323); p60-66 (3, 266)16%0.962.1 x 10-4*
p60-66 vs. p46-47Bonferroni post hoc t Test, two-tailedp60-66 (3, 266); p46-47 (2, 196)5%0.140.327
p46-47 vs. p21-28Bonferroni post hoc t Test, two-tailedp46-47 (2, 196); p21-28 (2, 152)2%0.070.669
Bouton Area
All AgesANOVA, one-way6.0 x 10-13*
>p90 vs. p60-66Bonferroni post hoc t Test, two-tailed>p90 (3, 319); p60-66 (3, 254)20%0.820.005*
p60-66 vs. p46-47Bonferroni post hoc t Test, two-tailedp60-66 (3, 254); p46-47 (2, 196)39%0.986.1 x 10-5*
p46-47 vs. p21-28Bonferroni post hoc t Test, two-tailedp46-47 (2, 196); p21-28 (2, 141)93%0.991.34 x 10-11*
Spinule Area
All AgesANOVA, one-way0.671
Spinule-Bearing Bouton Area
>p90 SBBs vs. No SpinulesMann-Whitney U test>p90 SBBs (3, 57); >p90 NoSpin (3, 266)88%0.992.69 x 10-9*
% Spinule-Bearing Boutons
2D
All Ages (4 x 2 table)X2 Test, two-tailed, Bonferroni corrected5.3 x 10-5*
>p90 vs. p60-66X2 Test, two-tailed, Bonferroni corrected>p90 (3, 319); p60-66 (3, 254)68%0.730.009*
p60-66 vs. p46-47X2 Test, two-tailed, Bonferroni correctedp60-66 (3, 254); p46-47 (2, 196)92%0.520.041
p46-47 vs. p21X2 Test, two-tailed, Bonferroni correctedp46-47 (2, 196); p21-28 (2, 141)8%0.040.863
FIBSEM
All Ages (4 x 2 table)< 1.0 x 10-5*
>p90 vs. p60X2 Test, two-tailed, Bonferroni corrected>p90 (1, 223); p60 (1, 235)67%0.810.008*
p60 vs. p46X2 Test, two-tailed, Bonferroni correctedp60 (1, 235); p46 (1, 157)127%0.700.014*
p46 vs. p21X2 Test, two-tailed, Bonferroni correctedp46 (1, 157); p21 (1, 61)3%0.030.959
% Perforated PSD
FIBSEM: All Boutons
All Ages (4 x 2 table)X2 Test, two-tailed, Bonferroni corrected0.003*
>p90 vs. p60X2 Test, two-tailed, Bonferroni corrected>p90 (1, 237); p60 (1, 256)61%0.820.004*
p60 vs. p46X2 Test, two-tailed, Bonferroni correctedp60 (1, 256); p46 (1, 163)11%0.060.639
p46 vs. p21X2 Test, two-tailed, Bonferroni correctedp46 (1, 163); p21 (1, 62)3%0.040.937
FIBSEM: SBBs vs. Non-SBBs
>p90 SBBs vs. Non-SBBsX2 Test, two-tailed, Bonferroni corrected>p90 SBBs (1,58); >p90 Non-SBBs (1,179)87%0.830.001*
p60 SBBs vs. Non-SBBsX2 Test, two-tailed, Bonferroni correctedp60 SBBs (1,40); p60 Non-SBBs (1,216)129%0.770.003*
Spinule Origins: >p90 vs. p60-66
% Postsynaptic Spine (>p90 vs. p60)X2 Test, two-tailed, Bonferroni corrected>p90 (1, 54); p60 (1, 34)152%0.630.024*
% Adjacent Axon (>p90 vs. p60)X2 Test, two-tailed, Bonferroni corrected>p90 (1, 54); p60 (1, 34)37%0.480.030*
% Adjacent Dendrite (>p90 vs. p60)X2 Test, two-tailed, Bonferroni corrected>p90 (1, 54); p60 (1, 34)16%0.060.724
% Adjacent Spine (>p90 vs. p60)X2 Test, two-tailed, Bonferroni corrected>p90 (1, 54); p60 (1, 34)6%0.050.271
% Adjacent Glia (>p90 vs. p60)X2 Test, two-tailed, Bonferroni corrected>p90 (1, 54); p60 (1, 34)n/a0.240.161
  • Statistical tests used for 2D TEM and 3D FIBSEM analyses are listed, grouped by each quantified morphology category (left most column) and age group comparison (“Comparison” column). Percent change between means are calculated as: Embedded Image , where Age2 = Mean of older age group, and Age1 = Mean of younger age group. Power is the post-hoc two-tailed Fisher’s exact test achieved statistical power for each comparison, given the two proportions and sample sizes (n), with ∝ error probability = 0.05. * = comparisons where p < 0.05 or Bonferroni corrected value. Sample sizes for SBB vs. Non-SBB perforated PSDs reflect the total number of SBB and Non-SBB synapses for each age group, and ‘n’ for ‘Spinule Origins’ comparisons reflect the total number of spinule-bearing boutons (SBBs) within each group. PSDs = Postsynaptic densities. 2D = TEM analyses. Non-SBBs = excitatory presynaptic boutons without spinules.