Fig. 5. Effects of neurotrophins on soma size in primary visual cortex layer IV neurons, and layer VI neurons given in the small insets. White bars represent contralateral and black bars ipsilateral values. (A) Size frequency histograms reveal that cytochrome C control was not effective. (B) BDNF, however, consistently induced dramatic shifts to larger sizes (MWU-test, ipsi versus contra, P<0.0001). (C) In contrast, NT-4/5 did not induce growth of layer IV neurons (diamonds) and layer VI neurons (circles) during the P20-28 infusions. However, the early P12-20 infusions did result in a significant growth of layer IV (triangles up) and layer VI neurons (triangles down), indicating a developmental time window of responsiveness to NT-4/5. (D) NGF did not evoke any growth. The small insets indicate the percentage of median shift in the individual animals analyzed. At P20-28, only the values for BDNF infused animals differed from controls (one way ANOVA, Tukey's post hoc test).