Figure 12

Segregation of cervical and lumbar limb moving motoneurons based on somatopetal propagation of voltage transients. Cluster analysis was used with the Pair group and Ward’s methods (see horizontal labels starting with ‘pg’ and ‘wm’) with differently weighted (‘fact1’ and ‘fact2’) descriptors. These descriptors were the standardized and area weighted percentiles of somatic to dendritic ratios of peak potentials (open triangles), half-widths (closed circles) and rise times (open circles) of PSPs to quantify the changes in shape of voltage transients generated by conductance changes according to an α-function (g_max = 2 nS, t_max = 1.5 ms). Last order clustering index (A) and Peterson’s homogeneity index (B) were used to measure homogeneities within last order clusters, which reflect segregation of cervical and lumbar MNs between these clusters. Homogeneity indexes with values closer to one indicate higher similarity (poorer segregation) of cervical and lumbar MNs. Continuous horizontal lines mark levels of homogeneities below which separation of MNs is significant. ‘High’, ‘Medium’, and ‘Low’ levels of synaptic background activities on dendrites were modeled by 5000, 20000 and 50000 Ωcm² specific dendritic membrane resistivities respectively.