Department of Psychobiology, Institute of Neurosciences, Center for Biomedical Research (CIBM), University of Granada, Spain.
Department of Psychobiology, Institute of Neurosciences, Center for Biomedical Research (CIBM), University of Granada, Spain.
Neurobiol Learn Mem. 2020 Oct;174:107277. doi: 10.1016/j.nlm.2020.107277. Epub 2020 Jul 21.
The attenuation of taste neophobia (AN) is a good model for studying the structural and neurochemical mechanisms of the emotional component of memory because taste recognition memory exhibits the unique feature of being necessarily linked to hedonic properties. Whilst novel tastes elicit cautious neophobic responses, taste exposures which are not followed by aversive consequences attenuate neophobia as the taste becomes safe and palatable. Given the involvement of the nucleus accumbens in reward and of the amygdala in emotional memories, we applied c-Fos immunohistochemistry as an index of neural activity in Wistar rats that were exposed to a vinegar solution for one, two or six days. An inverse pattern of accumbens nucleus vs amygdala activity was found on the second exposure day on which AN occurred. The number of c-Fos positive cells in the nucleus accumbens shell increased whilst the number of c-Fos positive cells in the basolateral amygdala decreased. Further analyses revealed a positive correlation between AN and the number of c-Fos positive cells in the accumbens shell but a negative correlation in the basolateral amygdala. Furthermore the accumbens-amygdala interplay relevant for AN seems to be mediated by dopamine D1 receptors (D1DR). The injection of SCH23390 (D1DR antagonist) in both the accumbens shell and the basolateral amygdala on the second taste exposure resulted in selectively impaired AN but had opposite long term effects. This finding supports the relevance of a dopaminergic network mediated by D1DRs in the nucleus accumbens shell and basolateral amygdala which is critical for adding the emotional component during the formation of taste memory.
味觉回避（AN）的衰减是研究情感成分记忆的结构和神经化学机制的良好模型，因为味觉识别记忆具有必然与愉悦属性相关联的独特特征。虽然新的味道会引起谨慎的回避反应，但如果没有不愉快的后果，味觉暴露会随着味觉变得安全和可口而减弱回避。鉴于伏隔核参与奖励，杏仁核参与情绪记忆，我们应用 c-Fos 免疫组织化学作为 Wistar 大鼠在接触醋酸溶液一天、两天或六天后神经活动的指标。在发生 AN 的第二天，发现伏隔核核与杏仁核的活动呈反模式。壳核中的 c-Fos 阳性细胞数量增加，而基底外侧杏仁核中的 c-Fos 阳性细胞数量减少。进一步的分析表明，AN 与壳核中的 c-Fos 阳性细胞数量呈正相关，而与基底外侧杏仁核中的 c-Fos 阳性细胞数量呈负相关。此外，与 AN 相关的伏隔核-杏仁核相互作用似乎是由多巴胺 D1 受体（D1DR）介导的。在第二次味觉暴露时，将 SCH23390（D1DR 拮抗剂）注射到壳核和基底外侧杏仁核中，会选择性地损害 AN，但会产生相反的长期影响。这一发现支持了多巴胺能网络在壳核和基底外侧杏仁核中由 D1DR 介导的相关性，这对于在味觉记忆形成过程中添加情感成分至关重要。
