Characteristics and organization of discharge properties in rat hindlimb motoneurons.
Characteristics and organization of discharge properties in rat hindlimb motoneurons.
复制标题
大鼠后肢运动神经元放电特性的特征和组织。
DOI：
10.1152/jn.00379.2010
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发表时间：
2010
影响因子：
2.5
通讯作者：
Hamm,ThomasM
中科院分区：
文献类型：
--
作者：
Turkin,VladimirV;O'Neill,Derek;Jung,Ranu;Iarkov,Alexandre;Hamm,ThomasM
The discharge properties of hindlimb motoneurons in ketamine–xylazine anesthetized rats were measured to assess contributions of persistent intrinsic currents to these characteristics and to determine their distribution in motoneuron pools. Most motoneurons (30/37) responded to ramp current injections with adapting patterns of discharge and the frequency–current (f–I) relations of nearly all motoneurons included a steep subprimary range of discharge. Despite the prevalence of adaptingf–Irelations, responses included indications that persistent inward currents (PICs) were activated, including increased membrane noise and prepotentials before discharge, as well as counterclockwise hysteresis and secondary ranges inf–Irelations. Examination of spike thresholds and afterhyperpolarization (AHP) trajectories during repetitive discharge revealed systematic changes in threshold and trajectory within the subprimary, primary, and secondaryf–Iranges. These changes in the primary and secondary ranges were qualitatively similar to those described previously for cat motoneurons. Within the subprimary range, AHP trajectories often included shallow approaches to threshold following recruitment and slope of the AHP ramp consistently increased until the subprimary range was reached. We suggest that PICs activated near recruitment contributed to these slope changes and formation of the subprimary range. Discharge characteristics were strongly correlated with motoneuron size, using input conductance as an indicator of size. Discharge adaptation, recruitment current, and frequency increased with input conductance, whereas both subprimary and primaryf–Igains decreased. These results are discussed with respect to potential mechanisms and their functional implications.
