GABAergic feedback signaling into the calyces of the mushroom bodies enables olfactory reversal learning in honey bees.
GABAergic feedback signaling into the calyces of the mushroom bodies enables olfactory reversal learning in honey bees.
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DOI：
10.3389/fnbeh.2015.00198
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发表时间：
2015
影响因子：
3
通讯作者：
Giurfa M
中科院分区：
文献类型：
--
作者：
Boitard C;Devaud JM;Isabel G;Giurfa M
在反向学习中，受试者首先学会对强化刺激A做出反应，而不是对非强化刺激B做出反应（A+ vs. B-），然后当刺激偶然性发生逆转时，必须学习相反的情况（A-vs. B+）。刺激效价的这种变化在刺激结果的水平上产生了暂时的模糊性，需要克服这种模糊性来解决第二种区分。蜜蜂（Apis mellifera）有效地掌握嗅觉领域的反向学习。蘑菇体（MB），昆虫大脑的高级结构，需要解决这个任务。在这里，我们的目的是揭示促进蜜蜂逆向学习的神经回路。我们训练蜜蜂使用嗅觉条件反射的吻延伸反射（PER）加上局部药理学抑制的γ-氨基丁酸（GABA）能信号在MB。我们发现，抑制离子型，但不代谢型GABA能信号到MB盏损害逆转学习，但完整的能力进行两个连续的元素嗅觉歧视与模糊的刺激价。相反，抑制离子型GABA能信号进入MB叶对逆转学习没有影响。因此，我们的研究结果是一致的反馈神经元（FN）提供离子型GABA能信号从MB叶的肾盏抵消模糊的刺激价在逆转学习的具体要求。
In reversal learning, subjects first learn to respond to a reinforced stimulus A and not to a non-reinforced stimulus B (A+ vs. B−) and then have to learn the opposite when stimulus contingencies are reversed (A− vs. B+). This change in stimulus valence generates a transitory ambiguity at the level of stimulus outcome that needs to be overcome to solve the second discrimination. Honey bees (Apis mellifera) efficiently master reversal learning in the olfactory domain. The mushroom bodies (MBs), higher-order structures of the insect brain, are required to solve this task. Here we aimed at uncovering the neural circuits facilitating reversal learning in honey bees. We trained bees using the olfactory conditioning of the proboscis extension reflex (PER) coupled with localized pharmacological inhibition of Gamma-AminoButyric Acid (GABA)ergic signaling in the MBs. We show that inhibition of ionotropic but not metabotropic GABAergic signaling into the MB calyces impairs reversal learning, but leaves intact the capacity to perform two consecutive elemental olfactory discriminations with ambiguity of stimulus valence. On the contrary, inhibition of ionotropic GABAergic signaling into the MB lobes had no effect on reversal learning. Our results are thus consistent with a specific requirement of the feedback neurons (FNs) providing ionotropic GABAergic signaling from the MB lobes to the calyces for counteracting ambiguity of stimulus valence in reversal learning.