PDF(Pubmed)
Abstract：
In early development, active sleep is the predominant sleep state before it is supplanted by quiet sleep. In rats, the developmental increase in quiet sleep is accompanied by the sudden emergence of the cortical delta rhythm (0.5-4 Hz) around postnatal day 12 (P12). We sought to explain the emergence of the cortical delta by assessing developmental changes in the activity of the parafacial zone (PZ), a medullary structure thought to regulate quiet sleep in adults. We recorded from the PZ in P10 and P12 rats and predicted an age-related increase in neural activity during increasing periods of delta-rich cortical activity. Instead, during quiet sleep, we discovered sleep-dependent rhythmic spiking activity-with intervening periods of total silence-phase locked to a local delta rhythm. Moreover, PZ and cortical delta were coherent at P12 but not at P10. PZ delta was also phase locked to respiration, suggesting sleep-dependent modulation of PZ activity by respiratory pacemakers in the ventral medulla. Disconnecting the main olfactory bulbs from the cortex did not diminish cortical delta, indicating that the influence of respiration on delta at this age is not mediated indirectly through nasal breathing. Finally, we observed an increase in parvalbumin-expressing terminals in the PZ across these ages, supporting a role for local GABAergic inhibition in the PZ\'s rhythmicity. The unexpected discovery of delta-rhythmic neural activity in the medulla-when cortical delta is also emerging-provides a new perspective on the brainstem\'s role in regulating sleep and promoting long-range functional connectivity in early development.
摘要：
在早期发展中,主动睡眠是在被安静睡眠取代之前的主要睡眠状态。在老鼠身上,安静睡眠的发育增加伴随着出生后第12天（P12）左右皮质三角洲节律的突然出现（0.5-4Hz）。我们试图通过评估面旁区（PZ）活动的发育变化来解释皮质三角洲的出现，一种被认为调节成人安静睡眠的髓质结构。我们记录了P10和P12大鼠的PZ，并预测了在富含δ的皮质活动增加期间与年龄相关的神经活动增加。相反，在安静的睡眠中，我们发现了依赖睡眠的有节奏的尖峰活动，其中总的沉默阶段的中间阶段被锁定为局部的δ节奏。此外，PZ与皮质δ在P12处相干，但在P10处不相干。PZ三角洲也被锁相呼吸，提示腹侧延髓呼吸起搏器对PZ活动的睡眠依赖性调节。将主要嗅球与皮质断开连接并没有减少皮质三角洲，表明在这个年龄段呼吸对三角洲的影响不是通过鼻呼吸间接介导的。最后,我们观察到PZ中表达小清蛋白的末端在这些年龄增加，支持局部GABA能抑制在PZ的节律性中的作用。当皮质三角洲也出现时，在延髓中发现了三角洲节律性神经活动，这为脑干在调节睡眠和促进早期发育中的远程功能连接的作用提供了新的视角。
