Separate amygdala subregions signal surprise and predictiveness during associative fear learning in humans
Separate amygdala subregions signal surprise and predictiveness during associative fear learning in humans
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DOI：
10.1111/ejn.12094
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发表时间：
2013-03-01
影响因子：
3.4
通讯作者：
Buechel, Christian
中科院分区：
文献类型：
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作者：
Boll, Sabrina;Gamer, Matthias;Buechel, Christian
最近有人提出，杏仁核中的学习信号最好的特征可能是联想学习的注意理论[如PearceHall(PH)]，以及更新的结合了RescorlaWagner和PH学习模型的混合变体。在这些模型中，无符号预测误差(PEs)决定了线索的关联性，而线索又被用来动态控制结果预期的学习，并反映了先前结果预测可靠性的函数。在这里，我们使用了一个厌恶的巴甫洛夫反转学习任务来研究来自这样一个混合模型的计算信号。与以前的描述不同，我们的范式允许在线索呈现时对关联性进行单独评估，在结果时对PES进行单独评估。我们将这一方法与高分辨率功能磁共振成像相结合，以了解人类杏仁核的不同亚区如何对联想学习做出贡献。杏仁皮质内侧和中脑的信号变化在结果发生时代表了无标记的PES，显示出无论休克是意外施加还是被忽略，反应都增加了。相反，杏仁核基底外侧区域的活动与线索呈现时的关联性呈负相关。因此，皮质内侧杏仁核和中脑反映的是即刻的惊讶，而基底外侧杏仁核代表的是预测性，当结果预测变得更加可靠时，会显示出更多的反应。这些结果扩展了之前关于杏仁核中PH样机制的发现，并为人类杏仁核在联想学习过程中的回路提供了独特的见解。
It has recently been suggested that learning signals in the amygdala might be best characterized by attentional theories of associative learning [such as PearceHall (PH)] and more recent hybrid variants that combine RescorlaWagner and PH learning models. In these models, unsigned prediction errors (PEs) determine the associability of a cue, which is used in turn to control learning of outcome expectations dynamically and reflects a function of the reliability of prior outcome predictions. Here, we employed an aversive Pavlovian reversal-learning task to investigate computational signals derived from such a hybrid model. Unlike previous accounts, our paradigm allowed for the separate assessment of associability at the time of cue presentation and PEs at the time of outcome. We combined this approach with high-resolution functional magnetic resonance imaging to understand how different subregions of the human amygdala contribute to associative learning. Signal changes in the corticomedial amygdala and in the midbrain represented unsigned PEs at the time of outcome showing increased responses irrespective of whether a shock was unexpectedly administered or omitted. In contrast, activity in basolateral amygdala regions correlated negatively with associability at the time of cue presentation. Thus, whereas the corticomedial amygdala and the midbrain reflected immediate surprise, the basolateral amygdala represented predictiveness and displayed increased responses when outcome predictions became more reliable. These results extend previous findings on PH-like mechanisms in the amygdala and provide unique insights into human amygdala circuits during associative learning.