Rapid eye movement (REM) sleep, also referred to as paradoxical sleep for the striking resemblance of its electroencephalogram (EEG) to the one observed in wakefulness, is characterized by the occurrence of transient events such as limb twitches or facial and rapid eye movements. Here, we investigated the local activity of the primary somatosensory or barrel cortex (S1) in naturally sleeping head-fixed male mice during REM. Through local field potential recordings, we uncovered local appearances of spindle waves in the barrel cortex during REM concomitant with strong delta power, challenging the view of a wakefulness-like activity in REM. We further performed extra- and intracellular recordings of thalamic cells in head-fixed mice. Our data show high-frequency thalamic bursts of spikes and subthreshold spindle oscillations in approximately half of the neurons of the ventral posterior medial nucleus which further confirmed the thalamic origin of local cortical spindles in S1 in REM. Cortical spindle oscillations were suppressed, while thalamus spike firing increased, associated with rapid mouse whisker movements and S1 cortical activity transitioned to an activated state. During REM, the sensory thalamus and barrel cortex therefore alternate between high (wake-like) and low (non-REM sleep-like) activation states, potentially providing a neuronal substrate for mnemonic processes occurring during this paradoxical sleep stage.

快速眼动 (REM) 睡眠也被称为矛盾睡眠，因为其脑电图 (EEG) 与清醒状态下观察到的惊人相似，其特征是发生短暂事件，例如肢体抽搐或面部和快速眼球运动。在这里，我们研究了自然睡眠的头部固定雄性小鼠在快速眼动睡眠期间初级体感或桶状皮层（S1）的局部活动。通过局部场电位记录，我们发现了快速眼动期间桶状皮层中纺锤波的局部出现，并伴随着强大的δ功率，挑战了快速眼动期间类似觉醒活动的观点。我们进一步对头部固定小鼠的丘脑细胞进行了细胞外和细胞内记录。我们的数据显示，腹侧后内侧核的大约一半神经元存在丘脑高频尖峰爆发和阈下纺锤体振荡，这进一步证实了 REM 中 S1 局部皮质纺锤体的丘脑起源。皮质纺锤体振荡受到抑制，而丘脑尖峰放电增加，这与小鼠胡须的快速运动和 S1 皮质活动转变为激活状态有关。因此，在快速眼动睡眠期间，感觉丘脑和桶状皮层在高（觉醒样）和低（非快速眼动睡眠样）激活状态之间交替，可能为这个矛盾睡眠阶段发生的记忆过程提供神经元基质。