【双语版】什么是恐惧条件实验？/恐惧制约 What is Fear Conditioning?
恐惧条件实验的内容为联想式学习任务[1]，不了解条件反射实验的，可以参照
在实验中，首先对实验对象（小鼠）施加条件刺激（响声）和非条件刺激（电击）的组合，以使小鼠习得该条件刺激，表现出条件反射（惊吓后的停滞、静止）。
其次，通过将实验对象置于不同环境（通常为两种），设置不同的刺激组合，以条件反应的出现频率等来判断恐惧本身的习得与消失。
该实验常用来检测某种药物的效果，或研究特定脑区对恐惧反应的影响。[2]
流程大致如下：
第一天，在环境1（训练环境）中，小鼠被施加条件刺激和非条件刺激的组合，刺激间存在时间间隔。
第二天，在环境2（光源，地板材质等不同）中，仅施加条件刺激。
第三天，小鼠重新被安置于环境1，不施加任何刺激。
在此过程中，习得的条件反射常是完全的静止不动，且持续超过一定时间。三天内的条件反射都会被记录。
除了恐惧条件实验，还存在延迟恐惧条件实验，二者的区别在于后者施加两种刺激时，中间无时间间隔。
Fear Conditioning FC is a type of associative learning task, in which the subject (mice) learnt to associate stimulus by paired Conditional Stimuli CS (a tone) and Aversive Unconditional Stimuli US (mild electric shock), and this lead to its Conditional Response CR.
The mice is placed in different context. By recording the CR in different context with different set of stimuli, we can analyse how the learning goes of certain aversive stimuli.
The FC is often used to test certain drugs or to research on the process of learning fear for particular brain area.
The protocol usually goes as follows:
on the 1st day, the mice is put in Context A (also called the Training Context), and undergoes paired US (shock) and CS (tone), with the US occurs some time after the CS.
on the 2nd day, the mice is put in Context B (different floor texture or light source), and would be stimulated with CS alone.
on the 3rd day, the mice is put in Context A again with no stimuli.
During this process, the CR is usually defined as Freezing, a complete lack of motion which lasts longer than 0.75s. The CR in different context is recorded for further analysis.
Other than FC, there is also one called Delayed FC. The difference is that in the latter one, there is no time between US and CS.
参考：
[1] Fear Conditioning, https://med.stanford.edu/sbfnl/services/bm/lm/bml-fear.html
[2] Klein et al, .
