An interesting study discovered that NT-4/5 signaling occurring alone or in conjunction with BDNF-TrkB signaling might potentiate corticostriatal transmission; however, NT-4/5-TrkB-signaling can have an antagonistic effect on the BDNF-mediated modulation of corticostriatal transmission if it follows BDNF exposure in the context of striatal degeneration that mimics Huntington’s disease [110]. The gene discussed is BDNF; the disease is juvenile Huntington disease.