Distribution and characteristics of poststimulus effects in proximal and distal forelimb muscles from red nucleus in the monkey
Distribution and characteristics of poststimulus effects in proximal and distal forelimb muscles from red nucleus in the monkey
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DOI：
10.1152/jn.1998.79.4.1777
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发表时间：
1998-04-01
影响因子：
2.5
通讯作者：
Cheney, PD
中科院分区：
文献类型：
--
作者：
Belhaj-Saïf, A;Karrer, JH;Cheney, PD
我们使用肌电(EMG)活动的刺激触发平均(STTA)来研究猕猴大细胞红核(RNM)到达运动的功能组织的两个主要问题。第一个问题是，我们在以前的研究中报告的远端(手腕和手指)前肢肌肉是否明显偏向于伸肌的便利化，近端肌肉(肩部和肘部)是否也存在这种偏好。第二个问题是，远端和近端的肌肉是否可能由RNM共同促进，这表明协调伸展运动的功能性肌肉协同作用的存在。两只猴子接受了训练，以完成一项需要前肢多关节协调的抓取任务。记录24块前肢肌肉的肌电活动，包括5块肩部肌肉、7块肘部肌肉、5块腕部肌肉、5块手指肌肉和2块手部固有肌肉。在整个运动任务中给予微刺激(20微安，20赫兹)。在RNM的137个微刺激点中，共有977个刺激后效应，包括733个刺激后促进效应(PStF)和244个刺激后抑制效应(PStS)。在PStF效应中，58%来自远端肌肉；42%来自近端肌肉。手指肌肉(35%)比手腕、肘部或肩部肌肉(分别为20%、24%和18%)更容易促进。手内肌不常促进(3%)。在所有被测试的关节中，PStF在伸肌中比在屈肌中更常见。这种伸肌偏好在肩部(85%)、手腕(85%)和指部肌肉(94%)上非常强烈，而在肘部肌肉(60%)上则较弱。在PSTS效应中，65%在远端肌肉，35%在近端肌肉，有趣的是，屈肌比伸肌更容易抑制RNM。在72%的刺激部位，至少有两块肌肉被促进。这些部位中的大多数(61%)同时促进近端和远端肌肉。在其余部位(39%)，PStF出现在近端(17%)或远端肌肉(22%)。易化最常涉及肩部、肘部和远端肌肉的组合(30%)或肩部和远端肌肉(26%)。只有很少的手固有肌肉是整个肌肉协同作用的一部分。我们的结果表明，RNM 1)同时控制近端和远端肌肉，但影响的强度偏向远端肌肉；2)优先控制伸肌，不仅在前肢远端关节，而且在近端关节；3)输出区共同促进参与控制前肢伸展运动的近端和远端肌肉的协同作用。
We used stimulus-triggered averaging (StTA) of electromyographic (EMG) activity to investigate two major questions concerning the functional organization of the magnocellular red nucleus (RNm) for reaching movements in the macaque monkey. The first is whether the clear preference toward facilitation of extensor muscles we have reported in previous studies for distal (wrist and digit) forelimb muscles also exists for proximal muscles (shoulder and elbow). The second question is whether distal and proximal muscles may be cofacilitated from RNm suggesting the representation of functional muscle synergies for coordinated reaching movements. Two monkeys were trained to perform a prehension task requiring multijoint coordination of the forelimb. EMG activity was recorded from 24 forelimb muscles including 5 shoulder, 7 elbow, 5 wrist, 5 digit, and 2 intrinsic hand muscles. Microstimulation (20 mu A at 20 Hz) was delivered throughout the movement task. From 137 microstimulation sites in the RNm, a total of 977 poststimulus effects was obtained including 733 poststimulus facilitation effects (PStF) and 244 poststimulus suppression effects (PStS). Of the PStF effects, 58% were obtained from distal muscles; 42% from proximal muscles. Digit muscles were more frequently facilitated (35%) than the wrist, elbow, or shoulder muscles (20, 24, and 18%, respectively). The intrinsic hand muscles were infrequently facilitated (3%). At all joints tested, PStF was more common in extensor muscles than flexor muscles. This extensor preference was-very strong for shoulder (85%), wrist (85%), and digit muscles (94%) and weaker for elbow muscles (60%). Of the PStS effects, 65% were in distal muscles and 35% in proximal muscles, interestingly, the flexor muscles were more frequently inhibited from RNm than extensor muscles. At 72% of stimulation sites, at least two muscles were facilitated. The majority of these sites (61%) cofacilitated both proximal and distal muscles. At the remaining sites (39%), PStF was observed in either the proximal (17%) or distal muscles (22%). Facilitation most often involved combinations of shoulder, elbow, and distal muscles (30%) or shoulder and distal muscles (26%). Only rarely were intrinsic hand muscles part of the total muscle synergy. Our results show that the RNm 1) controls both proximal and distal muscles but the strength of influence is biased toward distal muscles, 2) preferentially controls extensor muscles not only at distal forelimb joints but also at proximal joints, and 3) output zones cofacilitate synergies of proximal and distal muscles involved in the control of forelimb reaching movements.