PATTERNS OF FACILITATION AND SUPPRESSION OF ANTAGONIST FORELIMB MUSCLES FROM MOTOR CORTEX SITES IN THE AWAKE MONKEY
PATTERNS OF FACILITATION AND SUPPRESSION OF ANTAGONIST FORELIMB MUSCLES FROM MOTOR CORTEX SITES IN THE AWAKE MONKEY
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DOI：
10.1152/jn.1985.53.3.805
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发表时间：
1985-01-01
影响因子：
2.5
通讯作者：
PALMER, SS
中科院分区：
文献类型：
--
作者：
CHENEY, PD;FETZ, EE;PALMER, SS
兴奋和抑制作用的模式产生拮抗前肢肌肉的单皮质内微刺激（S-ICMS）应用于运动皮质网站在猕猴进行斜坡和保持手腕运动。刺激触发的平均值（刺激TA）的整流肌电图（EMG）活动显示刺激后促进和/或抑制在确定屈肌和伸肌的手腕和手指。在22个皮质部位，还记录了单细胞的动作电位，并用于计算协变肌肉的尖峰触发平均值（尖峰TA）。在细胞活动的运动过程中被激活的一组肌肉在这里被称为“激动剂”;在相反方向的手腕运动过程中被激活的那些肌肉被称为“拮抗剂”。“（在没有分离细胞的部位，显示刺激后易化的肌肉被称为激动剂。）激动剂肌肉中的刺激后效应通常由激动剂亚组中的促进作用组成。观察到以下效应组合：激动剂肌肉的纯促进作用，对拮抗剂没有影响;激动剂和拮抗剂的促进作用;激动剂肌肉的促进作用，拮抗剂的相互抑制作用;“混合”促进和抑制抑制肌肉;和一些肌肉的纯抑制作用，对其拮抗剂没有影响。抑制作用最常见于屈肌;促进作用一般在伸肌中更强。在2只猴中发现了引起屈肌纯抑制而不促进伸肌的皮质部位。这些纯粹的抑制作用，观察不仅在刺激TA，但也在穗TA计算从单细胞在这些网站。其中一些细胞在手腕伸展时增加了它们的活性（但对伸肌没有可检测的影响）;其他细胞在屈曲时放电。皮层诱发的抑制由多突触中继介导。刺激后抑制的模式匹配相应的postspike模式计算的某些细胞在网站的刺激。运动皮层细胞形成影响相同或相似的目标运动神经元和抑制性中间神经元的输出细胞的功能聚集体。这样的分组支持穗TA编译相邻的皮层细胞，产生相同的配置文件postspike抑制肌肉活动。比较同一皮质部位单次和重复ICMS诱发的效应，以评估时间总和的贡献。在许多情况下，由S-ICMS诱发的阈下刺激后易化的轮廓类似于由重复ICMS诱发的EMG活动。一连串刺激还可以激活不直接受S-ICMS影响的肌肉，从而表明重复的ICMS可能通过时间总和招募额外的通路。
Patterns of excitatory and inhibitory effects were produced in antagonistic forelimb muscles by single intracortical microstimuli (S-ICMS) applied to motor cortex sites in macaque monkeys performing ramp-and-hold wrist movements. Stimulus-triggered averages (stimulus-TA) of rectified electromyographic (EMG) activity revealed post-stimulus facilitation and/or suppression in identified flexor and extensor muscles of the wrist and fingers. At 22 cortical sites the action potentials of single cells were also recorded and used to compute spike-triggered averages (spike-TA) of covarying muscles. The set of muscles activated during the movement in which the cell was active are referred to here as "agonists"; those muscles active during wrist movement in the opposite direction are called "antagonists." (At sites where cells were not isolated the muscles showing poststimulus facilitation were called agonists.) Poststimulus effects in agonist muscles typically consisted of facilitation in a subset of the agonists. The following combinations of effects were observed: pure facilitation of agonist muscles with no effect on antagonists; facilitation of both agonists and antagonists; facilitation of agonist muscles with reciprocal suppression of antagonists; "mixed" facilitation and suppression of synergist muscles; and pure suppression of some muscles with no effect on their antagonists. The suppression effects appeared most commonly in flexor muscles; facilitation was generally stronger in extensors. Cortical sites eliciting pure suppression of flexor muscles with no facilitation of extensor muscles were found in 2 monkeys. These purely suppressive effects were observed not only in stimulus-TA but also in spike-TA computed from single cells at these sites. Some of these cells increased their activity during wrist extension (but had no detectable effect on the extensor muscles); others discharged during flexion. The cortically evoked suppression is mediated by polysynaptic relays. The pattern of poststimulus suppression matched the corresponding postspike pattern computed for certain cells at sites of stimulation. Motor cortex cells form functional aggregates of output cells that affect the same or similar sets of target motoneurons and inhibitory interneurons. Such grouping was supported by spike-TA compiled for neighboring cortical cells that produced the same profile of postspike suppression of muscle activity. The effects evoked by single and repetitive ICMS from the same cortical sites were compared to assess the contribution of temporal summation. In many cases the profile of subthreshold poststimulus facilitation evoked by S-ICMS resembled the EMG activity evoked by repetitive ICMS. Trains of stimuli could also activate muscles not directly affected by S-ICMS, thus suggesting that repetitive ICMS may recruit additional pathways by temporal summation.