How does the brain maintain fear within an adaptive range? We found that the insular cortex acts as a state-dependent regulator of fear that is necessary to establish an equilibrium between the extinction and maintenance of fear memories in mice. Whereas insular cortex responsiveness to fear-evoking cues increased with their certainty to predict harm, this activity was attenuated through negative bodily feedback that arose from heart rate decelerations during freezing. Perturbation of body-brain communication by vagus nerve stimulation disrupted the balance between fear extinction and maintenance similar to insular cortex inhibition. Our data reveal that the insular cortex integrates predictive sensory and interoceptive signals to provide graded and bidirectional teaching signals that gate fear extinction and illustrate how bodily feedback signals are used to maintain fear within a functional equilibrium.

中文翻译：

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恐惧平衡是通过对小鼠岛叶皮层的身体反馈来维持的

大脑如何将恐惧保持在一个适应范围内？我们发现岛叶皮层是一种依赖于状态的恐惧调节器，这是在小鼠恐惧记忆的消退和维持之间建立平衡所必需的。虽然岛叶皮层对引发恐惧的线索的反应随着它们预测伤害的确定性而增加，但这种活动通过冰冻期间心率减速引起的负面身体反馈而减弱。迷走神经刺激对身体-大脑交流的干扰破坏了恐惧消退和维持之间的平衡，类似于岛叶皮层抑制。