Time determines the neural circuit underlying associative fear learning.
Time determines the neural circuit underlying associative fear learning.
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DOI：
10.3389/fnbeh.2011.00089
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发表时间：
2011
影响因子：
3
通讯作者：
Moita MA
中科院分区：
文献类型：
--
作者：
Guimarãis M;Gregório A;Cruz A;Guyon N;Moita MA
最终，联想学习是时间特征和所经历的刺激之间的关系的函数。然而，时间如何影响这种学习形式背后的神经回路，在很大程度上仍然是未知的。为了解决这个问题，我们使用了单次试验听觉跟踪恐惧条件反射，并改变了音调和脚震之间的间隔长度。通过暂时失活的杏仁核，内侧前额叶皮层（mPFC），背海马在大鼠中，我们测试的假设，不同的时间间隔之间的音调和冲击影响必要的学习神经元结构。通过这项研究，我们提供了第一个实验证据，表明当音调和电击之间存在时间间隔时，在训练前暂时失活杏仁核会损害听觉恐惧学习。此外，在两个刺激之间施加短的间隔（5秒）也依赖于mPFC，而在较长的间隔（40秒）上学习关联则额外依赖于第三个结构，即背海马。因此，我们的研究结果表明，增加音调和电击之间的间隔长度导致越来越多的大脑区域的参与，以使两种刺激之间的关联被正常获取。这些发现表明，事件之间的时间关系是决定联想恐惧学习的神经机制的关键因素。
Ultimately associative learning is a function of the temporal features and relationships between experienced stimuli. Nevertheless how time affects the neural circuit underlying this form of learning remains largely unknown. To address this issue, we used single-trial auditory trace fear conditioning and varied the length of the interval between tone and foot-shock. Through temporary inactivation of the amygdala, medial prefrontal-cortex (mPFC), and dorsal-hippocampus in rats, we tested the hypothesis that different temporal intervals between the tone and the shock influence the neuronal structures necessary for learning. With this study we provide the first experimental evidence showing that temporarily inactivating the amygdala before training impairs auditory fear learning when there is a temporal gap between the tone and the shock. Moreover, imposing a short interval (5 s) between the two stimuli also relies on the mPFC, while learning the association across a longer interval (40 s) becomes additionally dependent on a third structure, the dorsal-hippocampus. Thus, our results suggest that increasing the interval length between tone and shock leads to the involvement of an increasing number of brain areas in order for the association between the two stimuli to be acquired normally. These findings demonstrate that the temporal relationship between events is a key factor in determining the neuronal mechanisms underlying associative fear learning.
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