Department of Neurobiology, Weizmann Institute of Science, Rehovot, 76100, Israel.
Nat Commun. 2018 Oct 26;9(1):4460. doi: 10.1038/s41467-018-07020-4.
Associative learning forms when there is temporal relationship between a stimulus and a reinforcer, yet the inter-trial-interval (ITI), which is usually much longer than the stimulus-reinforcer-interval, contributes to learning-rate and memory strength. The neural mechanisms that enable maintenance of time between trials remain unknown, and it is unclear if the amygdala can support time scales at the order of dozens of seconds. We show that the ITI indeed modulates rate and strength of aversive-learning, and that single-units in the primate amygdala and dorsal-anterior-cingulate-cortex signal confined periods within the ITI, strengthen this coding during acquisition of aversive-associations, and diminish during extinction. Additionally, pairs of amygdala-cingulate neurons synchronize during specific periods suggesting a shared circuit that maintains the long temporal gap. The results extend the known roles of this circuit and suggest a mechanism that maintains trial-structure and temporal-contingencies for learning.
当刺激和强化物之间存在时间关系时，就会形成联想学习，但试验间间隔（ITI）通常比刺激-强化物间隔长得多，这有助于学习率和记忆强度。使试验间时间得以维持的神经机制尚不清楚，也不清楚杏仁核是否能够支持数十秒量级的时间尺度。我们表明，ITI 确实调节了厌恶学习的速度和强度，灵长类动物杏仁核和背侧前扣带皮层中的单个神经元在 ITI 内标记特定的时间段，在获得厌恶关联时增强这种编码，并在消退期间减弱。此外，杏仁核-扣带皮层神经元对特定时间段的同步表明存在一个共享电路，该电路维持了长的时间间隙。这些结果扩展了该电路的已知作用，并提出了一种维持学习的试验结构和时间关联的机制。
