Mind/Brain Institute, Johns Hopkins University, Baltimore, MD, 21218, USA.
Department of Neuroscience, Johns Hopkins University, Baltimore, MD, 21205, USA.
Nat Commun. 2022 Jun 9;13(1):3202. doi: 10.1038/s41467-022-30827-1.
Reinforcement allows organisms to learn which stimuli predict subsequent biological relevance. Hebbian mechanisms of synaptic plasticity are insufficient to account for reinforced learning because neuromodulators signaling biological relevance are delayed with respect to the neural activity associated with the stimulus. A theoretical solution is the concept of eligibility traces (eTraces), silent synaptic processes elicited by activity which upon arrival of a neuromodulator are converted into a lasting change in synaptic strength. Previously we demonstrated in visual cortical slices the Hebbian induction of eTraces and their conversion into LTP and LTD by the retroactive action of norepinephrine and serotonin Here we show in vivo in mouse V1 that the induction of eTraces and their conversion to LTP/D by norepinephrine and serotonin respectively potentiates and depresses visual responses. We also show that the integrity of this process is crucial for ocular dominance plasticity, a canonical model of experience-dependent plasticity.
强化使生物体能够学习哪些刺激预测随后的生物学相关性。突触可塑性的赫布机制不足以解释强化学习，因为与刺激相关的神经活动相对于与生物相关性相关的神经调节信号延迟。一个理论上的解决方案是资格痕迹（eTrace）的概念，由活动引发的沉默突触过程，当神经调节剂到达时，会转化为突触强度的持久变化。以前，我们在视觉皮层切片中证明了 eTrace 的赫布诱导及其通过去甲肾上腺素和 5-羟色胺的回溯作用转化为长时程增强和 LTD。在这里，我们在体内显示，在小鼠 V1 中，eTrace 的诱导及其分别通过去甲肾上腺素和 5-羟色胺转化为 LTP/D，增强和抑制视觉反应。我们还表明，该过程的完整性对于眼优势可塑性（经验依赖性可塑性的典型模型）至关重要。
