Both Corticospinal and Reticulospinal Tracts Control Force of Contraction
Both Corticospinal and Reticulospinal Tracts Control Force of Contraction
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DOI：
10.1523/jneurosci.0627-21.2022
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发表时间：
2022-04-13
影响因子：
5.3
通讯作者：
Baker, Stuart N.
中科院分区：
文献类型：
--
作者：
Glover, Isabel S.;Baker, Stuart N.
收缩力的控制是运动控制的关键部分。在灵长类动物中，皮质脊髓和网状脊髓细胞都为运动神经元提供输入。已知皮质脊髓放电与力相关，但以前没有关于网状结构（RF）活动如何调节不同收缩的报道。在这里，我们训练了两只雌性猕猴（体重，5.9-6.9 kg）拉动一个可以装载0.5-6 kg重物的手柄，并在任务执行过程中从初级运动皮层和RF细胞中识别出的锥体束神经元（PTNs）中记录。人口平均发射率单调增加，更高的力的RF，但表现出一个复杂的配置文件，几乎没有净调制的PTNs。这反映了PTN人群中速率调制的更异质性特征，导致平均值的取消。线性判别分析分类的力量的基础上的时间进程的速率调制同样好的PTNs和RF细胞。92个PTNs中有43个（46.7%）和46个RF细胞中有21个（43.5%）的峰值放电频率与力呈显著线性相关。对于几乎所有的RF细胞（21个中的20个），相关系数是正的;相似数量的PTNs（22个对21个）具有正与负的系数。考虑到力表示的时间，类似的分数（PTNs：61.2%; RF细胞：55.5%）开始编码肌肉活动开始之前。我们的结论是，皮质脊髓束和网状脊髓束有助于控制收缩力;网状脊髓束似乎指定一个整体信号简单地与力，而皮质脊髓细胞的活动将更适合于精细尺度的调整。
The control of contraction strength is a key part of movement control. In primates, both corticospinal and reticulospinal cells provide input to motoneurons. Corticospinal discharge is known to correlate with force, but there are no previous reports of how reticular formation (RF) activity modulates with different contractions. Here we trained two female macaque monkeys (body weight, 5.9-6.9 kg) to pull a handle that could be loaded with 0.5-6 kg weights and recorded from identified pyramidal tract neurons (PTNs) in primary motor cortex and RF cells during task performance. Population-averaged firing rate increased monotonically with higher force for the RF, but showed a complex profile with little net modulation for PTNs. This reflected a more heterogeneous profile of rate modulation across the PTN population, leading to cancellation in the average. Linear discriminant analysis classified the force based on the time course of rate modulation equally well for PTNs and RF cells. Peak firing rate had significant linear correlation with force for 43 of 92 PTNs (46.7%) and 21 of 46 RF cells (43.5%). For almost all RF cells (20 of 21), the correlation coefficient was positive; similar numbers of PTNs (22 vs 21) had positive versus negative coefficients. Considering the timing of force representation, similar fractions (PTNs: 61.2%; RF cells: 55.5%) commenced coding before the onset of muscle activity. We conclude that both corticospinal and reticulospinal tracts contribute to the control of contraction force; the reticulospinal tract seems to specify an overall signal simply related to force, whereas corticospinal cell activity would be better suited for fine-scale adjustments.