Somatic size of pyramidal neurons in layer V of the motor cortex and inter-hemispheric differences. A: Box and whisker plots showing the distribution of somatic cross-sectional areas of SMI-32 positive neurons in layer V in M1 for the three groups of monkeys. In the box and whisker plots, the thick horizontal line in the box corresponds to the median value, whereas the top and bottom of the box are for the 75 and 25 percentile values respectively. The top and bottom extremities of the vertical lines on each side of the box are for the 90 and 10 percentile values, respectively. All but one lesioned monkey (red and blue bars) exhibited a significant inter-hemispheric difference of cross-sectional soma area (* = p < 0.05; ** = p < 0.001; *** = p < 0.0001; Mann and Whitney test), whereas in the intact monkeys the difference was not statistically significant (n.s. = p > 0.05; Mann and Whitney test). B: Inter-hemispheric percent difference in the number of SMI-32 positive neurons per unit length in layer V in M1 for the same three groups of monkeys as in Figure 1C (same color code), plotted as a function of the lesion extent (percent of the territory corresponding to the CS and RS tracts affected by the lesion). Note that the differences are not systematic with respect to the side of the lesion in the two groups of lesioned animals (red squares and blue circles for the anti-Nogo-A and control antibody treated monkeys, respectively). In the percent comparison, 100% is for the number of SMI-32 positive neurons per unit length on the ipsilesional side (on the left side for the intact monkeys). The green triangles are for the intact monkeys. As the lesion extent could not be determined for Mk-AT (see Table 1), its corresponding percent value was represented by an horizontal dashed line. C: Inter-hemispheric percent difference of the median value of the cross-sectional soma area of SMI-32 positive neurons in layer V in M1 for the same three groups of monkeys as in panel A, plotted as a function of the lesion extent (percent of the territory corresponding to the CS and RS tracts affected by the lesion). Note that the difference is small for the intact monkeys (green symbols), but it is more prominent and systematic with respect to the side of the lesion for most lesioned monkeys, with considerable overlap between the two groups of lesioned monkeys. Same conventions as in panel B.