title: SK channels modulate the excitability and firing precision of projection neurons in the robust nucleus of the arcopallium in adult male zebra finches.
abstract: OBJECTIVE
  Motor control is encoded by neuronal activity. Small conductance Ca(2+)-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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: School of Life Science, South China Normal University, Key Laboratory of Ecology and Environmental Science in Higher Education of Guangdong Province, Guangzhou 510631, China.
authors.forename: Guo-Qiang
authors.initials: GQ
authors.lastname: Hou
authors.forename: Xuan
authors.initials: X
authors.lastname: Pan
authors.forename: Cong-Shu
authors.initials: CS
authors.lastname: Liao
authors.forename: Song-Hua
authors.initials: SH
authors.lastname: Wang
authors.forename: Dong-Feng
authors.initials: DF
authors.lastname: Li
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D001030:Apamin / Q000494:pharmacology; D046369:Finches; D066298:In Vitro Techniques; D008297:Male; D009474:Neurons / Q000502:physiology*; D016548:Prosencephalon / Q000502:physiology*; D051640:Small-Conductance Calcium-Activated Potassium Channels / Q000187:drug effects / Q000378:metabolism*
chemical_list: D051640:Small-Conductance Calcium-Activated Potassium Channels; D001030:Apamin