预期错误在恐惧记忆更新中的作用与机制

依据错误驱动的学习理论, 行为预期结果与实际结果之间的不匹配即预期错误(Prediction error, PE)是学习产生的驱动因素。作为显著性信息中的一种, 预期错误和物理显著性、惊讶、新异性等存在信息加工阶段的不同, 与记忆更新的关系也有差异。近年来, 记忆再巩固干预范式(reconsolidation interference)被证明可用于人类条件性恐惧记忆的更新, 其中记忆提取激活阶段所包含的预期错误起到了引发记忆“去稳定”、开启记忆再巩固的关键作用。在促进恐惧记忆更新的行为机制上, PE被认为是记忆去稳定的必要非充分条件。记忆提取必须包含适量的PE, 但其引发的是记忆去稳定、消退还是中间状态, 还需结合记忆本身性质确定。在促进恐惧记忆更新的神经机制上, 杏仁核、导水管周围灰质(PAG)、海马均在PE探测和计算过程中具有重要作用; 前额叶皮层(PFC)及其亚区在PE开启记忆再巩固过程中扮演了重要角色。上述过程又受到神经系统中特定神经递质的重要调节, 尤其是多巴胺能和谷氨酸能。未来研究应进一步探索基于PE计算模型的量化研究, 整合PE与其他边界条件的交互作用, 考察不同类型显著性在记忆再巩固中的作用等; 并亟待使用多学科手段探索PE在恐惧记忆更新中作用的神经与分子机制。同时, 需进一步开展PE作用的个体差异研究, 促进研究结果向临床应用转化。

The function and mechanisms of prediction error in updating fear memories

The error-driven learning theory believes that the reinforcement brought by the stimulus must be surprising or unpredictable for the individual to form learning. The mismatch between the expected consequence of behavior and the actual result, known as prediction error (PE), is the driving factor of learning, according to this theory. The Rescorla & Wagner model, the Pearce-Hall model, and the temporal difference (TD) model are the three most common models for calculating prediction error. The RW model and the TD model, in particular, have had a significant impact on the research of prediction error-driven learning and memory. Under different learning models, prediction error is classified as reward or punishment prediction error (RPE or PPE); positive or negative prediction error; and singed or unsigned prediction error (SPE or UPE). As a type of salience, PE is different from other types of saliences. Salience includes stimulus novelty, valence evaluation, stimulus rareness and other salience. Physical salience, surprise (unexpected novelty), and expected novelty are all types of novelty, but only unexpected novelty can promote dopamine release; physical salience with no direct rewards can only cause a short spike in dopamine. Prediction error, on the other hand, are mostly related to the recognition, result perception, and valence evaluation processes.