Key Laboratory of Ecology and Environmental Science in Higher Education of Guangdong Province, School of Life Sciences, South China Normal University, Guangzhou 510631, China.
Neural Plast. 2012;2012:931780. doi: 10.1155/2012/931780. Epub 2012 May 20.
The song of zebra finch is stable in life after it was learned successfully. Vocal plasticity is thought to be a motor exploration that can support continuous learning and optimization of performance. The activity of RA, an important pre-motor nucleus in songbird's brain, influences the song directly. This variability in adult birdsong is associated with the activity of NMDA receptors in LMAN-RA synapses, but the detailed mechanism is unclear. The control of gain refers to modulation of a neuron's responsiveness to input and is critically important for normal sensory, cognitive, and motor functions. Here, we observed the change of gain in RA projection neurons after exogenous NMDA was applied to activate NMDA receptors using the whole-cell current clamp recording. We found that NMDA substantially increased the slope (gain) of the firing rate-current relationship in RA projection neurons. The AMPA receptor-dependent excitability played a crucial role in the modulation of gain by NMDA. These results suggested that NMDA receptors may regulate the dynamics of RA projection neurons by input-output gain.
斑胸草雀的歌声在成功习得后会保持稳定。人们认为发声可塑性是一种运动探索，它可以支持持续的学习和性能优化。鸣禽大脑中一个重要的前运动核 RA 的活动直接影响着歌声。成年鸟鸣的这种可变性与 LMAN-RA 突触中 NMDA 受体的活性有关，但详细的机制尚不清楚。增益控制是指对神经元对输入的反应性的调制，对正常的感觉、认知和运动功能至关重要。在这里，我们使用全细胞膜片钳记录观察到，外源性 NMDA 激活 NMDA 受体后，RA 投射神经元的增益发生了变化。我们发现 NMDA 显著增加了 RA 投射神经元的放电率-电流关系的斜率（增益）。AMPA 受体依赖性兴奋性在 NMDA 对增益的调制中起着至关重要的作用。这些结果表明，NMDA 受体可能通过输入-输出增益来调节 RA 投射神经元的动力学。
