Convergent mechanosensory input structures the firing phase of a steering motor neuron in the blowfly, Calliphora
Convergent mechanosensory input structures the firing phase of a steering motor neuron in the blowfly, Calliphora
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DOI：
10.1152/jn.1999.82.4.1916
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发表时间：
1999-10-01
影响因子：
2.5
通讯作者：
Dickinson, MH
中科院分区：
文献类型：
--
作者：
Fayyazuddin, A;Dickinson, MH
第一基底肌（B1）是苍蝇17个小转向肌肉之一，控制飞行过程中翅膀行程运动学的变化。B1通常是紧张性活跃的，在每个翼拍周期中激发单个锁相动作电位。激活阶段的变化会改变B1的生物力学特性，这反过来又会导致机翼运动的空气动力学相关变化。B1运动神经元（MNB 1）的锁相放电被认为是由来自翅膀和专门的平衡器官（称为Halteres）的翼拍同步输入的相互作用引起的，Halteres与翅膀反相跳动，并在飞行期间检测身体的角旋转。我们研究了如何机翼和笼头输入相互作用，以确定发射阶段的MNB 1。我们的研究结果表明，翼和haltere传入与MNB 1，包括快速的电和慢的Ca 2+敏感的组件，使强大的单突触连接。虽然翅膀和haltere-evoked兴奋性突触后电位（EPSP）显示的两个组成部分，其相对贡献是不同的两个输入。而haltere-evoked EPSP是由快速的电成分为主，翅膀诱发的EPSP是由一个大的化学介导的组件，并显示一个额外的延长Ca 2+依赖的组件，是不存在的haltere-evoked EPSP。两种输入都显示影响电和Ca 2+敏感组件的活动依赖性疲劳，Haltere突触从中恢复得更快。这些突触差异的最终结果是，这两种途径在诱发MNB 1动作电位的相对能力方面存在显着差异。虽然haltere途径显示更大的时间精度，翅膀途径更强，判断其能力夹带MNB 1的背景下的haltere刺激。我们提出了一个模型，通过该模型，这些生理差异在调整飞行过程中MNB 1的发射相位中发挥了功能性作用。机翼输入可以主要用于设置MNB 1的背景点火相位，而笼头输入感测在平衡反射期间瞬时地推进点火相位。
The first basalar muscle (B1) is 1 of 17 small steering muscles in flies that control changes in wing stroke kinematics during flight. The B1 is often tonically active, firing a single phase-locked action potential in each and every wingbeat cycle. Changes in activation phase alter the biomechanical properties of B1, which in turn cause aerodynamically relevant changes in wing motion. The phase-locked firing of the B1 motor neuron (MNB1), is thought to arise from an interaction of wingbeat-synchronous inputs from the wings and from specialized equilibrium organs called halteres that beat antiphase to the wings and function to detect angular rotation of the body during flight. We investigated how the wing and haltere inputs interact to determine the firing phase of MNB1. Our results indicate that both wing and haltere afferents make strong monosynaptic connections with MNB1, consisting of fast electrical and slow Ca2+-sensitive components. Although both the wing and haltere-evoked excitatory postsynaptic potentials (EPSPs) display the two components, their relative contribution is different for the two inputs. Whereas the haltere-evoked EPSP is dominated by the fast electrical component, the wing-evoked EPSP is dominated by a large chemically mediated component and displays an additional prolonged Ca2+-dependent component that is absent in the haltere-evoked EPSP. Both inputs display an activity dependent fatigue affecting both electrical and Ca2+-sensitive components, from which the haltere synapse recovers more rapidly. The net result of these synaptic differences is that the two pathways differ significantly in their relative ability to evoke action potentials in MNB1. Although the haltere pathway displays greater temporal precision, the wing pathway is stronger, judged by its ability to entrain MNB1 within a background of haltere stimulation. We propose a model by which these physiological differences play a functional role in tuning the firing phase of MNB1 during flight. The wing input may serve primarily to set the background firing phase of MNB1, whereas the haltere input sen cs to transiently advance the firing phase during equilibrium reflexes.