Developmental trends of TrkB immunoreactivity during the first 3 postnatal weeks in the PBC (A), Amb (B), XII (C), NTSVL (D), NTSCOM (E), RTN/pFRG (F), and CN (G). A significant reduction occurred at P12 in all nuclei except for CN. (H) Developmental trend of TrkB mRNA in XII analyzed with RT-qPCR, showing the lowest value at P12. Tukey’s Studentized test comparing one age group with its immediately adjacent younger age group. *P < 0.05; **P < 0.01; ***P < 0.001. (Modified from Liu and Wong-Riley, 2013 for all except C and H, which are modified from Gao et al., 2014).