Warren R A, Jones E G
Department of Anatomy and Neurobiology, University of California, Irvine, California 92697, USA.
J Neurosci. 1997 Jan 1;17(1):277-95. doi: 10.1523/JNEUROSCI.17-01-00277.1997.
Postnatal development of physiological properties underlying slow intrathalamic oscillations was studied by whole-cell recording from synaptically coupled neurons of the reticular nucleus (RTN) and ventral posterior nucleus (VPN) of mouse brain slices in vitro and compared with the morphological development of dye-injected cells. Between postnatal days 3 and 11 (P3-P11), progressive changes in RTN and VPN neurons included shortening of the membrane time constant, decreasing input resistance, and lowering of the resting membrane potential (RMP). Low-threshold Ca2+ spikes (LTS) were present from P3, but their capacity to sustain multispike bursts was limited before P11. Synaptic responses were evoked in RTN and VPN neurons by electrical stimulation of the internal capsule from P3. Younger RTN neurons responded with a single spike, but their capacity to fire bursts gradually improved as the RMP reached levels below the LTS activation potential. Concomitantly, as the reversal potential of the inhibitory postsynaptic potential in VPN neurons became more negative, its capacity to deinactivate the LTS increased, and rebound bursts that could maintain oscillations were produced; sustained oscillations became the typical response to internal capsule stimulation at P12. The functional maturation of the intrathalamic circuitry, particularly between P10 and P14, occurs in parallel with the morphological maturation (size, dendritic growth, and dendritic field structure) of individual RTN and VPN neurons, as studied by confocal microscopy. Maturation of RTN cells led that of VPN cells by 2-3 d. The appearance of intrathalamic oscillations is probably correlated with the appearance of slow-wave sleep in postnatal animals.
通过在体外对小鼠脑片网状核（RTN）和腹后核（VPN）的突触耦合神经元进行全细胞记录，研究了丘脑内缓慢振荡的生理特性的产后发育，并将其与染料注射细胞的形态发育进行了比较。在出生后第3天至第11天（P3 - P11）之间，RTN和VPN神经元的渐进性变化包括膜时间常数缩短、输入电阻降低以及静息膜电位（RMP）下降。低阈值Ca2 + 尖峰（LTS）从P3开始出现，但在P11之前它们维持多峰爆发的能力有限。从P3开始，通过电刺激内囊在RTN和VPN神经元中诱发突触反应。较年轻的RTN神经元以单个尖峰做出反应，但随着RMP达到低于LTS激活电位的水平，它们爆发放电的能力逐渐提高。与此同时，随着VPN神经元中抑制性突触后电位的反转电位变得更负，其使LTS去失活的能力增加，并产生了能够维持振荡的反弹爆发；在P12时，持续振荡成为对内囊刺激的典型反应。如通过共聚焦显微镜研究所示，丘脑内电路的功能成熟，特别是在P10和P14之间，与单个RTN和VPN神经元的形态成熟（大小、树突生长和树突场结构）同时发生。RTN细胞的成熟比VPN细胞早2 - 3天。丘脑内振荡的出现可能与产后动物慢波睡眠的出现相关。
