RIKEN Brain Science Institute, Wako, Saitama, Japan.
PLoS One. 2011;6(10):e25879. doi: 10.1371/journal.pone.0025879. Epub 2011 Oct 3.
Reactivations of waking experiences during sleep have been considered fundamental neural processes for memory consolidation. In songbirds, evidence suggests the importance of sleep-related neuronal activity in song system motor pathway nuclei for both juvenile vocal learning and maintenance of adult song. Like those in singing motor nuclei, neurons in the basal ganglia nucleus Area X, part of the basal ganglia-thalamocortical circuit essential for vocal plasticity, exhibit singing-related activity. It is unclear, however, whether Area X neurons show any distinctive spiking activity during sleep similar to that during singing. Here we demonstrate that, during sleep, Area X pallidal neurons exhibit phasic spiking activity, which shares some firing properties with activity during singing. Shorter interspike intervals that almost exclusively occurred during singing in awake periods were also observed during sleep. The level of firing variability was consistently higher during singing and sleep than during awake non-singing states. Moreover, deceleration of firing rate, which is considered to be an important firing property for transmitting signals from Area X to the thalamic nucleus DLM, was observed mainly during sleep as well as during singing. These results suggest that songbird basal ganglia circuitry may be involved in the off-line processing potentially critical for vocal learning during sensorimotor learning phase.
睡眠期间觉醒体验的再现被认为是记忆巩固的基本神经过程。在鸣禽中，有证据表明睡眠相关的神经元活动对于幼年鸣禽学习和成年鸣禽歌曲的维持在歌唱运动核团的感觉运动通路核中很重要。与歌唱运动核中的神经元类似，基底神经节核团 X 区（基底神经节-丘脑皮质回路的一部分，对于发声可塑性至关重要）的神经元也表现出与歌唱相关的活动。然而，尚不清楚 Area X 神经元在睡眠期间是否表现出任何与歌唱期间相似的独特尖峰活动。在这里，我们证明在睡眠期间，Area X 苍白球神经元表现出相位尖峰活动，其与歌唱期间的活动具有一些发射特性。在清醒期间几乎只在歌唱期间出现的较短的尖峰间隔也在睡眠期间观察到。与清醒时非歌唱状态相比，歌唱和睡眠时的发射变异性水平始终更高。此外，被认为是将信号从 Area X 传递到丘脑核 DLM 的重要发射特性的发射率减速主要在睡眠期间以及歌唱期间观察到。这些结果表明，鸣禽基底神经节回路可能参与离线处理，这对于感觉运动学习阶段的发声学习至关重要。
