Model of ensemble connectivity among hypothalamic gonadotropin-releasing hormone (GnRH), pituitary luteinizing hormone (LH), and gonadal testosterone (Te) signals mediated via nonlinear interface functions. Te feedback is imposed on virtual GnRH outflow, defined as combined secretion (amount) and action (efficacy) of GnRH. SHBG, sex hormone-binding globulin. Te Sec, Te secretion.