These observations collectively underscore the critical importance of the postnatal window in the long-term programming of anxiety- and despair-like behavior, as chronic CNO-mediated hM3Dq DREADD activation of CamKIIα-positive forebrain excitatory neurons is sufficient to establish persistent changes in these behaviors only when administered during the postnatal window, with no such effect noted when the same chemogenetic activation is performed either in juvenile life or in adulthood. The gene discussed is CAMK2A; the disease is Anxiety.