SK channels modulate the excitability and firing precision of projection neurons in the robust nucleus of the arcopallium in adult male zebra finches  

作　　者：Guo-Qiang Hou Xuan Pan Cong-Shu Liao Song-Hua Wang Dong-Feng Li 

机构地区：[1]School of Life Science,South China Normal University,Key Laboratory of Ecology and Environmental Science in Higher Education of Guangdong Province,Guangzhou 510631,China

出　　处：《Neuroscience Bulletin》2012年第3期271-281,共11页神经科学通报（英文版）

基　　金：supported by grants from the National Natural Science Foundation of China (30970363 and 31172092)

摘　　要：Objective Motor control is encoded by neuronal activity. Small conductance Ca2＋-activated K＋ channels （SK channels） maintain the regularity and precision of firing by contributing to the afterhyperpolarization （AHP） of the action potential in mammals. However, it is not clear how SK channels regulate the output of the vocal motor system in songbirds. The premotor robust nucleus of the arcopallium （RA） in the zebra finch is responsible for the output of song information. The temporal pattern of spike bursts in RA projection neurons is associated with the timing of the acoustic features of birdsong. Methods The firing properties of RA projection neurons were analyzed using patch clamp whole-cell and cell-attached recording techniques. Results SK channel blockade by apamin decreased the AHP amplitude and increased the evoked firing rate in RA projection neurons. It also caused reductions in the regularity and precision of firing. RA projection neurons displayed regular spontaneous action potentials, while apamin caused irregular spontaneous firing but had no effect on the firing rate. In the absence of synaptic inputs, RA projection neurons still had spontaneous firing, and apamin had an evident effect on the firing rate, but caused no significant change in the firing regularity, compared with apamin application in the presence of synaptic inputs. Conclusion SK channels contribute to the maintenance of firing regularity in RA projection neurons which requires synaptic activity, and consequently ensures the precision of song encoding.Objective Motor control is encoded by neuronal activity. Small conductance Ca2＋-activated K＋ channels （SK channels） maintain the regularity and precision of firing by contributing to the afterhyperpolarization （AHP） of the action potential in mammals. However, it is not clear how SK channels regulate the output of the vocal motor system in songbirds. The premotor robust nucleus of the arcopallium （RA） in the zebra finch is responsible for the output of song information. The temporal pattern of spike bursts in RA projection neurons is associated with the timing of the acoustic features of birdsong. Methods The firing properties of RA projection neurons were analyzed using patch clamp whole-cell and cell-attached recording techniques. Results SK channel blockade by apamin decreased the AHP amplitude and increased the evoked firing rate in RA projection neurons. It also caused reductions in the regularity and precision of firing. RA projection neurons displayed regular spontaneous action potentials, while apamin caused irregular spontaneous firing but had no effect on the firing rate. In the absence of synaptic inputs, RA projection neurons still had spontaneous firing, and apamin had an evident effect on the firing rate, but caused no significant change in the firing regularity, compared with apamin application in the presence of synaptic inputs. Conclusion SK channels contribute to the maintenance of firing regularity in RA projection neurons which requires synaptic activity, and consequently ensures the precision of song encoding.

关 键 词：SK channels excitability firing precision robust nucleus of the arcopallium zebra finches 

分 类 号：Q463[生物学—生理学] Q954.52