At this point it might be useful to summarize our main conclusions from this section. Apparently the negative feedback (gonadotropin-inhibiting) as well as the behavioral responses to testosterone are both mediated by the hypothalamus. Different hypothalamic areas are however, involved. Testosterone implants widely distributed in the hypothalamus are effective in restoring male sex behavior but this is particularly evident when the implants are in the anterior hypothalamic-preoptic area (Table 4). On the other hand, negative feedback sensitivity appears limited to the basomedial region (Figs. 4 and 6). Behavioral activation is apparently achieved with testosterone levels considerably below the normal, while feedback inhibition of LH secretion appears to result from higher than normal levels of the hormone, suggesting that other factors than testosterone may possibly be involved in the normal feedback regulation.