Correlates of motivation and reward

记忆巩固是将新获得的信息转化为长期记忆的过程。外显记忆的巩固需要海马体，海马体产生一个与快速场振荡（200赫兹）相关的尖锐波，被称为涟漪6,7。海马波纹主要发生在慢波睡眠期间，已被证明在记忆巩固中起着至关重要的作用。然而，关于涟漪是如何被大脑的其他区域调节的，我们知之甚少。我们发现中缝正中核在调节海马纹波活动和记忆巩固中起着关键作用。我们对中缝正中核和海马进行了体内同步记录，发现当一组中缝神经元活跃时，没有波纹。为了确定因果关系，我们采用光遗传学方法，发现光刺激中缝神经元抑制海马纹波活动，而光抑制这些神经元增加海马纹波活动。重要的是，通过使用恐惧条件反射程序，我们提供了证据，证明中缝神经元的光刺激干扰记忆巩固。总之，我们的研究结果证明了中缝中核在调节海马纹波活动和记忆巩固方面的关键作用，并确定了控制这些生理学习和记忆过程的新的脑回路。

Memory consolidation is a process in which newly acquired information is transformed into long-term memory. Consolidation of explicit memory requires the hippocampus, which generates a sharp-wave associated fast field-oscillation (200 Hz), referred to as ripples6,7. Hippocampal ripples, which predominantly occur during slow-wave sleep, have been shown to play an essential role in memory consolidation. However, little is known about how ripples are regulated by other brain regions. Here we show that the median raphe nucleus plays a key role in regulating hippocampal ripple activity and memory consolidation. We performed in vivo simultaneous recordings in the median raphe nucleus and hippocampus, and found that when a group of raphe neurons were active, ripples were absent. To determine a causal relationship, we employed an optogenetic approach and found that photostimulation of median raphe neurons suppressed hippocampal ripple activity, while photoinhibition of these neurons increased hippocampal ripple activity. Importantly, by using a fear conditioning procedure, we provide evidence that photostimulation of median raphe neurons interferes with memory consolidation. In conclusion, our results demonstrate a critical role of the median raphe nucleus in regulating hippocampal ripple activity and memory consolidation, and identify a new brain circuitry that controls these physiological learning and memory processes.