Table 2.
Principal component analysis of increased and decreased activity
| Cumulative variance (%) | pc variance | Response | pc1 | pc2 | pc3 | pc4 | ||
|---|---|---|---|---|---|---|---|---|
| pc1 | 44.21030281 | 0.1629294 | Supragranular | Increased | 0.192969 | 0.4848809 | −0.312331 | 0.0005789 |
| pc2 | 71.03246885 | 0.0988484 | Decreased | 0.4076718 | −0.205153 | 0.1687933 | −0.0543012 | |
| pc3 | 92.99443819 | 0.080937 | Granular | Increased | 0.166108 | 0.2601034 | −0.3648693 | −0.0260106 |
| pc4 | 96.89447643 | 0.0143729 | Decreased | 0.3399926 | 0.2139566 | 0.2859596 | −0.5156428 | |
| pc5 | 98.60621637 | 0.0063083 | Infragranular | Increased | 0.0512769 | 0.4105422 | −0.0402117 | −0.1843402 |
| pc6 | 99.61462124 | 0.0037163 | Decreased | 0.4235365 | −0.2734356 | −0.2119353 | −0.3806003 | |
| pc7 | 99.83804586 | 0.0008234 | M1 | Increased | 0.084304 | 0.1439821 | −0.1092586 | 0.3450707 |
| pc8 | 99.94689553 | 0.0004011 | Decreased | 0.3603517 | −0.0147926 | 0.0682632 | 0.2510888 | |
| pc9 | 99.9710496 | 8.90E-05 | VPM | Increased | 0.1967974 | 0.2950371 | −0.2542239 | 0.0260476 |
| pc10 | 99.98996768 | 6.97E-05 | Decreased | 0.1489934 | 0.3088844 | 0.7176482 | 0.0854539 | |
| pc11 | 99.99776799 | 2.87E-05 | POM | Increased | −0.1273602 | 0.3553321 | 0.1261817 | 0.2783481 |
| pc12 | 100 | 8.23E-06 | Decreased | 0.5072061 | −0.1907687 | −0.0188202 | 0.5329833 |
Analysis of significant increased and decreased responses across all areas studied showed that two principal components (pcs) were able to explain a large portion of the sample's variance. The first component included mostly decreased activity from all S1 layers, M1, and POM, and increased activity in VPM. The second component included increased activity in all S1 layers, VPM, and POM, and decreased activity in VPM and all S1 layers. The presence of such a large portion of variance explained solely by two components indicates that common concurrent patterns of increased and decreased activity occur at all times in the TCLs, suggesting a distributed mode of processing during active tactile discrimination.