Table 1.
Parameters | Spiny neurons mean ± SD | P (spiny neurons vs. L4 IN) | Barrel inhibitor |
Noncluster 3 |
P (cluster 3 vs. noncluster 3) | P (cluster 3 vs. 2) | P (cluster 3 vs. 1) | |
---|---|---|---|---|---|---|---|---|
Cluster 3 mean ± SD | Cluster 2 mean ± SD | Cluster 1 mean ± SD | ||||||
Morphology | ||||||||
Total axon length (mm) | n/a | n/a | 16.0 ± 6.0 | 19.6 ± 7.0 | 25.5 ± 11.4 | ns | ns | <0.05 |
Axon barrel ratio | n/a | n/a | 0.89 ± 0.05 | 0.66 ± 0.06 | 0.28 ± 0.11 | <0.001 | <0.01 | <0.001 |
Static EP | ||||||||
AP half width (ms) | 1.10 ± 0.13 | <0.001 | 0.32 ± 0.08 | 0.39 ± 0.11 | 0.34 ± 0.10 | 0.1 | ns | ns |
AHP amplitude (mV) | −11.8 ± 1.7 | <0.01 | −16.0 ± 3.5 | −13.7 ± 3.8 | −15.7 ± 3.7 | 0.21 | ns | ns |
AP threshold (mV) | −40.8 ± 9.8 | 0.02 | −34.4 ± 7.6 | −33.3 ± 6.0 | −35.0 ± 5.4 | 0.99 | ns | ns |
Dynamic EP | ||||||||
Fmax (Hz) | 60 ± 9 | <0.001 | 279 ± 51 | 293 ± 88 | 280 ± 56 | 0.69 | ns | ns |
Adaptation ratio | 0.18 ± 0.10 | <0.001 | 0.67 ± 0.11 | 0.68 ± 0.14 | 0.75 ± 0.20 | 0.29 | ns | ns |
AHP difference (mV) | −7.6 ± 1.6 | <0.001 | 1.1 ± 1.1 | 1.8 ± 1.1 | 1.2 ± 0.6 | 0.25 | ns | ns |
Passive EP | ||||||||
Baseline Vm (mV) | −70.1 ± 8.2 | 0.10 | −67.2 ± 4.9 | −67.2 ± 4.8 | 64.2 ± 7.7 | 0.35 | ns | ns |
Membrane resistance (MΩ) | 138.9 ± 26.8 | <0.001 | 85 ± 19.8 | 91.2 ± 21.9 | 96.2 ± 19.8 | 0.14 | ns | ns |
Different morphological subtypes as defined by cluster analysis are represented by “barrel inhibitor” neurons (cluster 3) and 2 noncluster 3 subgroups (pooled data of cluster 1 and 2 interneurons). There was no difference in any physiological parameter between the 3 different morphological clusters of layer 4 interneurons (ANOVA with Dunn's post-test analysis; ns, nonsignificant). When compared with L4 interneurons (L4 IN), L4 spiny neurons showed differences in all physiological parameters except baseline membrane voltage (n/a, nonapplicable).