Contrasting properties of motor output from the supplementary motor area and primary motor cortex in rhesus macaques
Contrasting properties of motor output from the supplementary motor area and primary motor cortex in rhesus macaques
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DOI：
10.1093/cercor/bhj009
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发表时间：
2006-05-01
期刊：
影响因子：
3.7
通讯作者：
Cheney, PD
中科院分区：
文献类型：
--
作者：
Boudrias, MH;Belhaj-Saïf, A;Cheney, PD
本研究的目的是评估辅助运动区（SMA）的前肢表征的运动输出能力，包括对肌电图（EMG）活动的影响的迹象、潜伏期和强度。在伸手抓握任务中，用SMA计算前肢24块肌肉的刺激触发的肌电图活动平均值。SMA的刺激后促进（PStF）有两个明显的峰（15.2和55.2 ms）和一个刺激后抑制（PStS）峰（32.4 ms）。SMA的短潜伏期PStF和pst分别比初级运动皮层（M1）长5.5和16.8 ms。60亩A时短潜伏期PStF和长潜伏期PStF的平均幅度（高于基线的峰值增加或减少）分别为13.8%、11.3和-11.9%。相比之下，15亩A的M1 PStF和pst震级分别为50.2%和-23.8%。将M1 PStF的大小外推到60 μ A，产生的平均效应几乎是SMA平均PStF的15倍。此外，与M1不同，SMA对远端肌肉的促进作用并不显著大于近端肌肉的促进作用。我们得出的结论是，与M1相比，SMA向运动神经元的输出明显较弱，这引发了对SMA皮质脊髓神经元在直接控制肌肉活动中的作用的怀疑。
The goal of this study was to assess the motor output capabilities of the forelimb representation of the supplementary motor area (SMA) in terms of the sign, latency and strength of effects on electromyographic (EMG) activity. Stimulus triggered averages of EMG activity from 24 muscles of the forelimb were computed in SMA during a reach-to-grasp task. Poststimulus facilitation (PStF) from SMA had two distinct peaks (15.2 and 55.2 ms) and one poststimulus suppression (PStS) peak (32.4 ms). The short onset latency PStF and PStS of SMA were 5.5 and 16.8 ms longer than those of the primary motor cortex (M1). The average magnitudes (peak increase or decrease above baseline) of the short and long latency PStF and PStS from SMA at 60 mu A were 13.8, 11.3 and -11.9% respectively. In comparison, M1 PStF and PStS magnitudes at 15 mu A were 50.2 and -23.8%. Extrapolating M1 PStF magnitude to 60 mu A yields a mean effect that is nearly 15 times greater than the mean PStF from SMA. Moreover, unlike M1, the facilitation of distal muscles from SMA was not significantly greater than the facilitation of proximal muscles. We conclude that the output from SMA to motoneurons is markedly weaker compared with M1 raising doubts about the role of SMA corticospinal neurons in the direct control of muscle activity.