Figure 7
Comparison of morphoelectrotonic transformations with their original geometry in (A) cervical and (B) lumbar MNs. Somatopetal log attenuations of PSPs were computed from thousands of dendritic locations per neuron and divided by the mean attenuation calculated from locations within 100 μm from the soma. Finally, these ratios (relative log attenuations) were averaged and graphed over 100 μm path distance ranges from the soma. Attenuation ratios were computed in four different models of MNs by using 1.4 MΩ neuron resistance with homogeneous (Rms = Rmd) and inhomogeneous (Rms < Rmd) soma-dendritic membranes (closed and open rectangles) and by 5 MΩ neuron resistance with homogeneous and inhomogeneous membranes (closed and open circles). In homogeneous membrane models Rmd was equal to Rms, in inhomogeneous models Rmd = 20000 Ωcm2 was assumed. The common specific membrane resistance for the soma and dendrites in homogeneous models and the Rms values in inhomogeneous models were defined to have neurons with 1.4 or 5 MΩ input resistance measured at the soma. Continuous linear thick line is a reference where data points would be positioned if METs cause proportional changes in size of dendrites relative to their morphological appearance. Note that many error bars, representing S.E.M.s, are too small to be visible because of the high numbers of sampling sites.