It has been shown that fear conditioning improves the steady-state evoked potentials driven by a long lasting amplitude modulated tone in the inferior colliculus. In this work we tested the hypothesis that the amygdala modulates this effect, since it plays a crucial role in assessing the biological relevance of environmental stimuli. We inhibited the basolateral nucleus of the amygdala of rats by injecting a GABAa receptor agonist (muscimol) before the recall test session of an auditory fear conditioning paradigm and recorded the evoked activity in the central nucleus of the inferior colliculus. According to our results, the treatment with muscimol decreased the expression of freezing behavior during the recall test session, but did not impair the entrainment of the evoked activity in the inferior colliculus induced by fear conditioning. We repeated the injection protocol with another group of rats but without pairing the tone to an aversive stimulus and observed that the inhibition of the basolateral amygdala enhances the stimulus-driven activity in the inferior colliculus regardless of the conditioning task. Our findings suggest that the basolateral amygdala exerts a tonic modulation over the encoding of sensory information at the early stages of the sensory pathway.

研究表明，恐惧调节可改善下丘的长幅度调变音调驱动的稳态诱发电位。在这项工作中，我们测试了杏仁核调节这种效应的假设，因为杏仁核在评估环境刺激的生物学相关性中起着至关重要的作用。我们通过在听觉恐惧条件范式的召回测试之前注射GABAa受体激动剂（muscimol）抑制大鼠杏仁核的基底外侧核，并记录下丘中央核的诱发活动。根据我们的结果，使用麝香酚进行治疗可降低召回测试期间的冰冻行为表达，但不会损害恐惧条件引起的下丘脑诱发的活动。我们对另一组大鼠重复了注射方案，但未将音调与厌恶刺激配对，并观察到基底外侧杏仁核的抑制作用增强了下丘脑中刺激驱动的活动，而与调节任务无关。我们的发现表明，基底外侧杏仁核在感觉途径的早期阶段对感觉信息的编码施加了强直调节。