The lateral septum and anterior hypothalamus act in tandem to regulate burying in the shock-probe test but not open-arm avoidance in the elevated plus-maze

• Muscimol in the LS and contralateral AHA reduced shock-probe burying.
• This same treatment left open-arm avoidance intact.
• Communication between the LS and AHA serves a specialized role in behavioral defense regulation.
• The LS-AHA circuit appears to mediate responses to discrete but not potential threats.

Both the lateral septum (LS) and anterior hypothalamus (AHA) regulate behavioural defense. We tested whether those two interconnected structures act in serial in that regard. Infusions of the GABAA agonist muscimol into one side of the LS and the contralateral (but not ipsilateral) AHA suppressed rats’ burying in the shock-probe test whereas none of our muscimol infusion approaches altered their open-arm avoidance in the elevated plus-maze. These results suggest that the LS–AHA circuit serves a specialized role in defensive responses towards discrete, localizable threat stimuli but not towards potential threats.