Dual encoding of muscle tension and eye position by abducens motoneurons.
Dual encoding of muscle tension and eye position by abducens motoneurons.
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DOI：
10.1523/jneurosci.5416-10.2011
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发表时间：
2011-02-09
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影响因子：
--
通讯作者：
Pastor AM
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作者：
Davis-López de Carrizosa MA;Morado-Díaz CJ;Miller JM;de la Cruz RR;Pastor AM
与自发眼球运动相关的眼外肌张力具有与运动神经元放电频率相似的脉冲-滑动-步进曲线。现有的模型仅将运动神经元放电与眼睛位置、速度和加速度联系起来。我们测量并定量比较了外直肌肌力和眼位与猫外展肌运动神经元放电的关系，以确定基本的编码相关性。在固定（步骤），肌肉力量呈指数增加偏心眼的位置，一致的模型估计合奏运动神经支配的基础上神经元的敏感性和招聘秩序。此外，发射率在所有的运动神经元测试是更好地与眼睛的位置，而不是在固定过程中的肌肉张力。相反，在后扫视滑动阶段，放电率衰减的时间常数密切相关的肌肉力量衰减，这表明所有的运动神经元编码肌肉张力。外展肌运动神经元的放电特征形成了相性和强直性运动神经元的重叠簇，因此，强直性单位招募更早，具有更大的幻灯片信号。我们的结论是，幻灯片信号是一个放电特性的运动神经元，控制肌肉张力在后扫视阶段和运动神经元专门为紧张和位置相关的属性。组织的信号内容的池外展肌运动神经元非常相位非常紧张的单位可能是一个结果的差异营养背景收到不同类型的肌纤维。
Extraocular muscle tension associated with spontaneous eye movements has a pulse-slide-step profile similar to that of motoneuron firing rate. Existing models only relate motoneuron firing to eye position, velocity and acceleration. We measured and quantitatively compared lateral rectus muscle force and eye position with the firing of abducens motoneurons in the cat to determine fundamental encoding correlations. During fixations (step), muscle force increased exponentially with eccentric eye position, consistent with a model of estimate ensemble motor innervation based on neuronal sensitivities and recruitment order. Moreover, firing rate in all motoneurons tested was better related to eye position than to muscle tension during fixations. In contrast, during the postsaccadic slide phase, the time constant of firing rate decay was closely related to that of muscle force decay, suggesting that all motoneurons encode muscle tension as well. Discharge characteristics of abducens motoneurons formed overlapping clusters of phasic and tonic motoneurons, thus, tonic units recruited earlier and had a larger slide signal. We conclude that the slide signal is a discharge characteristic of the motoneuron that controls muscle tension during the post-saccadic phase and that motoneurons are specialized for both tension and position-related properties. The organization of signal content in the pool of abducens motoneurons from the very phasic to the very tonic units is possibly a result of the differential trophic background received from distinct types of muscle fibers.