SYNCHRONIZATION OF MOTOR UNIT FIRING DURING DIFFERENT RESPIRATORY AND POSTURAL TASKS IN HUMAN STERNOCLEIDOMASTOID MUSCLE
SYNCHRONIZATION OF MOTOR UNIT FIRING DURING DIFFERENT RESPIRATORY AND POSTURAL TASKS IN HUMAN STERNOCLEIDOMASTOID MUSCLE
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DOI：
10.1113/jphysiol.1989.sp017650
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发表时间：
1989-06-01
影响因子：
5.5
通讯作者：
GUZ, A
中科院分区：
文献类型：
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作者：
ADAMS, L;DATTA, AK;GUZ, A
人类胸锁乳突肌的运动单位放电已被研究过。在肌肉中插入两个针电极，记录在(A)反射性高碳酸血症阻碍呼吸，(B)真核自愿复制(A)对抗相同吸气阻力和(C)真核自愿复制(A)无任何阻力，伴随着等长转颈的过程中的运动单位对的活动。单位对放电的互相关直方图显示出一个明显的中心峰值，表明同步。自主呼吸高峰持续时间平均为25ms(范围9~40ms)。在不同的任务中，同步的持续时间没有差异。在同步峰期间，对于反射性高碳酸血症呼吸障碍，以两个单位的伴随放电次数占总放电次数的比例表示的平均同步强度为0.026(范围0.011-0.058)。对于相同的单位对，等长颈部旋转的同步强度与反射性高二氧化碳呼吸时的同步强度相同，但对于自愿受阻的呼吸，同步强度平均增加三倍。在所研究的22个运动单位中，有3个在两种类型的呼吸受阻时，每次吸气开始时“放电”的间隔不到10毫秒(“双重”发射)；这种情况在转颈时很少观察到。结果被解释为在三个不同的任务中对运动单位的不同突触驱动。
Motor unit firing has been studied in human sternocleidomastoid muscle. Two needle electrodes were inserted into the muscle and the activity of pairs of motor units recorded during (a) reflex hypercapnic obstructed breathing, (b) eucapnic voluntary copying of (a) against the same inspiratory resistance and (c) eucapnic voluntary copying of (a) without any resistance, accompanied by isometric neck rotation. Cross-correlation histograms of the firing of unit pairs showed a clear central peak, indicative of synchronization. The mean duration of the peak during voluntary breathing was 25 ms (range 9-40 ms). There was no difference in duration of synchronization during the different tasks. For the duration of the synchronization peak, the mean strength of synchronization expressed as the number of concomitant discharges of the two units as a proportion of the total number of discharges was 0.026 (range 0.011-0.058) for reflex hypercapnic obstructed breathing. For the same unit pairs the strength of synchronization for isometric neck rotation was the same as that during reflex hypercapnic breathing but for voluntary obstructed breathing it was, on average, threefold greater. In three out of twenty-two motor units studied, ''discharge'' occurred with an interval of less than 10 ms (''doublet'' firing) at the onset of each inspiration during both types of obstructed breathing; this was rarely observed during neck rotation. The results are interpreted in terms of different synaptic drives to the motor units during the three different tasks.