Fast amplification of dynamic synaptic inputs in spinal motoneurons in vivo.
Fast amplification of dynamic synaptic inputs in spinal motoneurons in vivo.
复制标题
体内脊髓运动神经元动态突触输入的快速放大。
DOI：
10.1152/jn.00537.2006
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发表时间：
2006
影响因子：
2.5
通讯作者：
Lee,RobertH
中科院分区：
文献类型：
--
作者：
Jones,SarahM;Lee,RobertH
成年猫腰运动神经元的电压依赖性内向电流（可能是Na+）放大快速变化（即，动态）突触输入使用体内细胞内记录技术进行研究。通过测量Ia突触输入的高频（180 Hz）分量的大小来评估快速放大，该分量是由于肌腱振动作为体细胞电压的函数，并与先前观察到的稳定输入的放大（PIC对慢输入的稳态响应）进行比较。来自17个实验的数据表明，动态输入的放大确实发生了，并且与神经调节驱动直接相关（标准状态：去大脑与完整的下行神经调节系统相对于最小状态：戊巴比妥与所述系统显著抑制）。在标准神经调节状态下，快速放大因子平均为2.0 ± 0.7（平均值± SD）。也就是说，有效突触电流在峰值时几乎是超极化水平时的两倍，范围高达2.6。虽然快速放大通常小于稳定输入的放大，但差异在统计学上并不显著。而快速放大开始的电压比去极化电压高0.10mV（P< 0.01）。结果表明，动态输入和稳态输入都可以放大，但放大机理可能有所不同。
The ability of voltage-dependent inward currents (likely Na+) of the adult cat lumbar motoneurons to amplify rapidly changing (i.e., dynamic) synaptic inputs was investigated using in vivo intracellular recording techniques. Fast amplification was assessed by measuring the magnitude of the high-frequency (180 Hz) component of the Ia synaptic input due to tendon vibration as a function of somatic voltage and was compared with the previously observed amplification of steady inputs (steady state response of PICs to slow inputs). Data from 17 experiments show that amplification of the dynamic input indeed occurred and was directly linked to neuromodulatory drive (standard state: decerebrate with intact descending neuromodulatory systems vs. minimal state: pentobarbital with said systems significantly inhibited). Fast amplification factors averaged 2.0 ± 0.7 (mean ± SD) in the standard neuromodulatory state. That is, the effective synaptic current was nearly twice as large at its peak as it was at hyperpolarized levels, ranging as high as 2.6. Although fast amplification was often smaller than the amplification of steady inputs, the difference was not statistically significant. However, the voltage at which fast amplification began was ∼10 mV more depolarized (P< 0.01). It is concluded that both dynamic and steady inputs can be amplified, but there may be differences in mechanism.