Early Development of the Thalamic Inhibitory Feedback Loop in the Primary Somatosensory System of the Newborn Mice
Early Development of the Thalamic Inhibitory Feedback Loop in the Primary Somatosensory System of the Newborn Mice
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DOI：
10.1523/jneurosci.1671-09.2009
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发表时间：
2009-08-05
影响因子：
5.3
通讯作者：
Ropert, Nicole
中科院分区：
文献类型：
--
作者：
Evrard, Alexis;Ropert, Nicole
自发神经元活动在脑回路的最终发育和初级感觉地图的形成过程中起着重要作用。在年轻大鼠中，在初级躯体感觉皮层中记录到了纺锤波爆发。它们与自发的肌肉抽搐有关，发生在主动搅拌之前。它们与成年人大脑中记录的纺锤波相似，这些纺锤波发生在睡眠的早期阶段，并依赖于丘脑腹后内侧核（nVPM）和丘脑网状GABA能核（nRT）之间的丘脑反馈回路。然而，在新生啮齿动物中是否存在功能性nVPM-nRTloop尚不清楚。我们研究了nVPM和nRT之间的相互突触连接的小鼠从出生[出生后第0天（P0）]，直到P9的丘脑急性切片。我们首先证明，nVPM-nRT EPSC可以区分从皮质丘脑EPSC的抑制5-HT归因于功能性突触前5-羟色胺1B受体的瞬时表达。nVPM至nRT EPSC和nRT至nVPM IPSC均在出生后第1天检测到;其振幅在2 nS附近相对稳定，直到P5。在P6-P7，nVPM-至-nRT EPSC和nRT-至-nVPM IPSC均快速且同时增加，分别达到8和9 nS。我们的研究结果表明，丘脑突触参与纺锤体活动的功能出生后不久，这表明他们已经可以产生纺锤体在出生后的第一周。我们的结果还表明，5-HT对新生小鼠的纺锤波爆发的抑制作用。
Spontaneous neuronal activity plays an important role during the final development of the brain circuits and the formation of the primary sensory maps. In young rats, spindle bursts have been recorded in the primary somatosensory cortex. They are correlated with spontaneous muscle twitches and occur before active whisking. They bear similarities with the spindles recorded in adult brain that occur during early stages of sleep and rely on a thalamic feedback loop between the glutamatergic nucleus ventroposterior medialis (nVPM) and the GABAergic nucleus reticularis thalami (nRT). However, whether a functional nVPM-nRTloop exists in newborn rodents is unknown. We studied the reciprocal synaptic connections between nVPM and nRT in thalamic acute slices from mice from birth [ postnatal day 0 (P0)] until P9. We first demonstrated that nVPM-to-nRT EPSCs could be distinguished from corticothalamic EPSCs by their inhibition by 5-HT attributable to the transient expression of functional presynaptic serotonin 1B receptors. The nVPM-to-nRT EPSCs and nRT-to-nVPM IPSCs were both detected the first day after birth; their amplitude near 2 nS was relatively stable until P5. At P6-P7, there was a rapid and simultaneous increase of both nVPM-to-nRT EPSCs and nRT-to-nVPM IPSCs that reached 8 and 9 nS, respectively. Our results show that the thalamic synapses implicated in spindle activity are functional shortly after birth, suggesting that they could already generate spindles during the first postnatal week. Our results also suggest an inhibitory action of 5-HT on the spindle bursts of the newborn mice.