Functional relations between primate motor cortex cells and muscles: fixed and flexible.
Functional relations between primate motor cortex cells and muscles: fixed and flexible.
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灵长类运动皮层细胞和肌肉之间的功能关系：固定和灵活。
DOI：
10.1002/9780470513545.ch7
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发表时间：
1987
期刊：
影响因子：
--
通讯作者：
Cheney,PD
中科院分区：
文献类型：
--
作者：
Fetz,EE;Cheney,PD
在猴子的行为中，运动皮质细胞对肌肉的影响是从两种完全不同的“相关”证据中推断出来的：它们的共同激活和相互关联。许多中央前细胞与四肢肌肉共同激活，这表明它们对肌肉活动有一定比例的贡献；然而，这种共同激活通常是非常灵活的，可以通过手术调节细胞和肌肉活动的分离来改变。通过棘波触发的肌电(EMG)平均使细胞和肌肉相互关联，表明某些细胞产生EMG的短潜伏期后易化；这种关联在不同的行为条件下相对固定，其时间进程表明它是由皮质运动神经元(CM)突触连接介导的。CM细胞通常促进一组共同激活的激动肌，有些还抑制它们的拮抗者。CM细胞的放电模式可能与它们的目标肌肉显著不同。在腕部倾斜和保持反应中，大多数CM细胞在靶肌肉开始之前放出一次时相爆发，这有助于肌肉活动的改变。在低力水平下，许多CM细胞在没有目标运动单位的情况下被激活。相反，许多CM细胞在快速有力的运动中反常地不活跃，这些运动有力地激活了它们的目标肌肉；它们似乎在精细控制的运动中优先活跃。因此，与目标肌肉有固定关联的CM细胞可以在没有目标肌肉的情况下被招募，反之亦然。
In behaving monkeys the effects of motor cortex cells on muscles are inferred from two quite different types of ‘correlational’ evidence: their co‐activation and cross‐correlation. Many precentral cells are coactivated with limb muscles, suggesting that they make a proportional contribution to muscle activity; however, such coactivation is typically quite flexible, and can be changed by operantly conditioning the dissociation of cell and muscle activity. Cross‐correlating cells and muscles by spike‐triggered averaging of the electro‐myogram (EMG) shows that certain cells produce short‐latency post‐spike facilitation of EMG; this correlational linkage is relatively fixed under different behavioural conditions and its time course suggests it is mediated by a cortico‐motoneuronal (CM) synaptic connection. CM cells typically facilitate a set of coactivated agonist muscles, and some also inhibit their antagonists.The firing patterns of CM cells can differ significantly from those of their target muscles. During ramp‐and‐hold wrist responses most CM cells discharge a phasic burst that precedes target muscle onset and that contributes to changes in muscle activity. At low force levels many CM cells are activated without their target motor units. Conversely, many CM cells are paradoxically inactive during rapid forceful movements that vigorously activate their target muscles; they appear to be preferentially active during finely controlled movements. Thus CM cells, with a fixed correlational linkage to their target muscles, may be recruited without their target muscles, and vice versa.